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ANNUAL REPORT1975-76

PHYSICAL RESEARCH LABORATORYAhmedabad - 380 009

Contents Page

1. Council of Management

2. Finances

3. Introduction

4. Scientific Highlights

5. Research Programmes

Solar and Planetary Physics

Infrared Astronomy

Nuclear Theory

Plasma Theory

Laboratory Plasma & Astrophysics

Geocosmophysics

Archaeology and Hydrology

6. Facilities

LibraryComputer CentreTechniques LaboratoryWorkshop

Electronics LaboratoryPhotography—DocumentationEngineering Services

7. Rasearch Publications

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ii

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4

8

33

36

8. Papers Presented at Symposia/Conferences 41

9. Theses Submitted 45

10. Conferences/Symposia attended by PRL 46Scientists in India and Abroad

11. Visits to Universities, Research 51Organizations and talks given there

12. Lectures delivered by the visitors 54

COUNCIL OF MANAGEMENT 1975-76

Chairman

Prof. K. R. Ramanathan Representative of KarmakshetraEducation Foundation.

Members

Sheth Shri Kasturbhai Lalbhai Representative of the AhmedabadEducation Society.

Prof. S. DhawanChairmanSpace Commission andSecretary, Dept. of SpaceBangalore 560 009.

Prof. M. G. K. MenonChairmanElectronics Commission andSecretary, Dept. of ElectronicsVigyan Bhavan AnnexeNew Delhi 110 011

Shri M. A. VellodiAdditional SecretaryDepartment of SpaceBangalore 560 009

Nominees of the Government

of India.

Shri K. RamamurthyDirector of EducationGujarat StateAhmedabad 380 016.

Nominee of the Government ofGujarat

Prof. D. Lai(Ex-Officio)

DirectorPhysical Research Laboratory.

Secretary

Dr. Dinesh Patel(Ex-Officio)

Senior Administrative OfficerPhysical Research Laboratory

The Council held two meetings (23rd and 24th) on 2nd August1975 and 24th January 1976 respectively.

i

Introduction

The Physical Research Laboratory, established in 1947, is main-tained as a public trust, under a quadrupartite agreement with grantsfrom (a) the Karmakshetra Education Foundation, (b) the AhmedabadEducation Trust, (c) The Government of Gujarat and (d) the Governmentof India through the Department of Space.

During the first decade of its existence, PRL was primarily engagedin studies of time variations of cosmic rays and physics of the upperatmosphere. These programmes have continuously evolved alongsidedevelopment of new techniques and expertise at PRL, and growth ofknowledge in these fields. Today, PRL is engaged in a wide range ofproblems in planetary and space sciences. The current structure of thevarious scientific groups is as follows :

1. Solar Planetary Physics, which consists of

(i) Aeronomy studies - ground based as well as with theuse of rockets and satellites;

(ii) Cosmic rays and Interplanetary Space;(iii) Radio Astronomy - primarily solar.

2. Theoretical Physics, which consists of

(i) Nuclear Theory;(ii) Plasma Theory.

3. Laboratory Plasma Physics and Astrophysics, whichconsists of

(i) Experimental Plasma Physics;(ii) Laboratory Astrophysics.

4. Infra-red Astronomy.5. Nuclear Geophysics and Cosmophysics.6. Archaeology and Hydrology.

Programmes 3(ii) and 4 are relatively new areas of research.Experimental systems in these areas, namely. Laboratory Astrophysics andInfra-red Astronomy are under development. A powerful ultraviolet source,a photoelectron spectrometer and an UV monochromator are now nearingcompletion; these would allow study of photo-molecular reactions ofastrophysical importance. Work in the field of ground-based Infra-redAstronomy began in April 1975. Work is now in progress towards buildingan infra-red photometer and a Fourier Transform Spectrometer. Study ofinfra-red sources/regions will then be carried out using these instrumentswith existing 40" telescopes in India.

Other programmes listed above continue with modifications andsubstantial change in emphasis. A greater emphasis was laid on thestudy of the solar radiations and important solar-terrestrial relationships.Plans are underway to receive data from the 400 pound NRL SOLRAD11A and 11B satellites which were successfully launched from CapeCanaveral on 14th March, 1976.

The experimental Plasma Physics Group is functional and ready totackle important problems, e.g., equatorial etectrojet instabilities undercontrolled conditions. A large volume collisionless plasma machine hasbeen completed for the study of non-linear ion wave propagation.

Several of the new experiments have in factbecome possible with the availability of badly neededlaboratory space and development of new facilities,the glass blowing shop and the liquid nitrogen plant.The nine floor building was completed aroundFebruary 1976 but many of the groups moved inearlier even while the construction work was inprogress.

As before, the research activities are supportedby several common facilities, namely, the Electronicslaboratory, the Techniques laboratory, the Library,the Workshop and the Computer Centre. An Engi-neering Services Unit looks after the constructionand maintenance of buildings, electrical and aircon-ditioning facilities etc.

Four distinguished scientists have been selectedby an Expert Committee constituted by the PhysicalResearch Laboratory, for the Shri Hari Om AshramVikram Sarabhai Research Awards, endowed by HariOm Ashram, Nadiad. The endowment provides forfour awards annually in the fields of Electronics andTelecommunications; Planetary & Space Sciences;Systems Analysis and Management Problems andAtmospheric Physics and Hydrology. Each awardcarries a cash prize of Rs. 4,000/- and a Medal.This year no award was made in the field ofAtmospheric Physics and Hydrology. Instead twoseparate awards were made in the field of Planetaryand Space Sciences. The fields of research and thenames of the awardees are :

1. Mr. N. PantChairmanCommunication AreaSpace Applications CentreAhmedabad

Electronics andTelecommunications

2. Professor U. R. RaoDirectorISRO Satellite SystemsProject A 3 - 6, PeenyaIndustrial EstateBangalore

3. Dr. B. M. ReddyAssistant DirectorRadio Science DivisionNational Physical LaboratoryNew Delhi

Planetary and SpaceSciences

Planetary andSpace Sciences

4. Shri Pramod P. KaleCo-chairman Planning &Project GroupSpace Applications CentreAhmedabad

Systems Analysisand Management

The awards will be made on the next birthdayof the late Dr. Vikram A. Sarabhai, which falls on12th August, 1976, at an investiture ceremony tobe held at the Physical Research Laboratory,Ahmedabad.

Professor K. R. Ramanathan received the "PadmaVibhushan" award on the Republic Day, 1976.

Professor D. Lai was elected a Foreign Associateof the National Academy of Sciences of the UnitedStates of America.

The Federation of Indian Chambers of Commerceand Industry (FICCI) in recognition of individualinitiative in research in science and technology gavean award for the year 1974 to Professor D. Lai,jointly with Professor R. C. Mehrotra, Vice-Chancellor,Delhi University.

Dr. S. Krishnaswami was one of the 12 scientistsselected by the Indian National Science Academyfor the Science Academy Medals for young scientists.He was presented this award by the Prime Ministerat the 63rd Session of the Indian Science Congressat Waltair for his contributions in the developmentof methods of studying fossil tracks in minerais anddating fresh water ferromaganese minerals and corals,lakes and coastal sediments.

Professor S. Dhawan, Chairman, Space Com-mission, presented Achievement Awards to thefollowing 14 PRL scientists in recognition of theircontribution to the first Indian satellite, Aryabhata,launched into orbit on 19th April, 1975 :

1. Prof. Satya Prakash 8. Shri R. S. Singh

2. Prof. B. H. Subbaraya 9. Shri R. K. Patwardhan

3. Dr. Vijay Kumar 10. Shri K. S. Modh

4. Shri P. N. Pareek 11. Shri A. P. Gohil

5. Dr. J. S. Shirke 12. Shri T. M. Raval

6. Shri R. N. Mishra 13. Shri J. T. Vinchhi

7. Shri A. Banerjee 14. Shri G. A. Panchal

Yet another collaborative programme betweenPRL and SAC (Space Applications Centre, Ahme-dabad) was started; this consists of organisingjointly popular lectures on Science, Engineering andPublic Affairs. First of the lectures was delivered byProfessor G. Burbidge on January 1, 1976; the titleof the lecture was "Violence in Astronomy".

A Summer School, on problems in Theore-tical Plasma Physics was held at Saputara duringJune 2-14, 1975. This was arranged with a viewto evolve a national programme in plasma physicsand to create a sense of awareness amongst researchworkers about frontier problems in this field. Fiftyscientists (22 from PRL and 28 from other institu-tions in India) participated in the Summer School.Twenty six lectures were delivered in the field ofnon-linear plasma theory, fluid and plasma turbulenceand a general stability theory. Extensive discussionswere held in related research areas such as thephysics of the earth's magnetosphere and the ionos-phere, and solid state plasmas. A Proceedings con-taining the lectures has already been published.

A joint PRL-INCOSPAR-ISRO Symposium onSolar Planetary Physics was held during January20-24, 1976. In addition to about 100 local partici-pants, about 200 scientists from other researchinstitutions and universities outside Ahmedabad tookpart in the symposium. In about 20 reviews and150 contributed papers, a variety of topics werecovered such as solar physics, interplanetary medium,planetary atmospheres, cosmic rays; a greater empha-

sis was laid on discussions of the physics of theearth's magnetosphere, ionosphere and atmosphere.New observations of microstructure in the radioemission from the Sun, scintillation and Faradayrotation in the equatorial ionosphere over Ooty basedon monitoring ATS-6 geostationary satellite andionisation ledges by topside sounders were highlightsof the conference.

A Workshop on "Palaeoclimate and Archa-eology of Rajasthan and Gujarat" was held atPRL from the 23-26 February, 1976 to review thestate of research in palaeoclimate of western India.Extensive participation from several institutions inthe country (Archaeological Survey of India, Geolo-gical Survey of India, Central Arid Zone ResearchInstitute and several universities) ted to delineationof important climatic problems and decision.on someof the controversial issues. Concrete joint- projectswere outlined to reconstruct the palaeoclimate andpalaeo-environment of western India.

A brief report giving highlights of the scientificactivities during 1975-76 is given in the next section.A more detailed report appears later.

ScientificHighlights

SOLAR AND PLANETARY PHYSICS

The Solar and Planetary Physics Area continued its activities inrocket, satellite and ground based experimental studies of the Ionosphere,Radio Astronomy, Cosmic Rays and Interplanetary medium. The majorhigh-lights of the year are the following :

(a) Inter-institutional programme

The major effort of the area this year has been the installation ofan ATS-6 receiving station at the Radio Astronomy Centre, Ootacamundwithin the equatorial electrojet region. This set up loaned by NOAA, USArecords every 10 sees., on a magnetic tape, information on Faraday fading,group delay and amplitude scintillation on all the frequencies radiatedfrom ATS-6 viz; 40, 140 and 360 MHz. Unusually strong scintillationhas been detected during the daylight hours and is suggested to becaused by the blanketing Es layers. During the night time hours, un-expectedly stronger scintillations are recorded on 360 MHz as comparedto those on 40 and 140 MHz.

The construction of six 140 MHz polarimeters at PRL and theirinstallation at different University Centres in India marked a new chapterin extension of space research in the Universities in India with PRL.These results have shown the absence of the diurnal anomaly in TECeven on days when the latitudinal anomaly is significantly strong. Com-paring the records from various places, travelling ionospheric disturbances(TIDs) have been identified to travel all the way from the equator uptonorthern most latitude in India.

Another inter-institutional project has been started with the simul-taneous observations of high resolution pictures of the sun at optical andradio wave lengths with the cooperation of PRL at Ahmedabad and theVedhshala at Udaipur. A number of interesting features of solar distur-bances have been observed in November 1975 and March 1976.

(b) PRL Programmes

An experimental evidence for the existence of cross equatorial windsat F-region altitudes during solstice period is obtained by the spatialdisplacement of ionisation ledges in the topside ionosphere.

The occurrence of ionisation ledges in the equatorial topside ionos-sphere and the counter-electrojet in the E-region revealed good correla-tion. This is an interesting evidence of correlation between two phenomenaso widely separated in height in the equatorial ionosphere indicating acommon causative source.

The winds at lower thermosphere during daytime were measuredfor the first time in the electrojet region and the results are indicativeof dominant semidiurnal tide in this region.

For the first time, the electric fields in the equatorial electrojet regionhave been measured by a rocket-borne probe.

L

Rocket-borne Langmuir probe flown duringcounter-electro jet in the afternoon hours revealedledges of ionisation in the 90-95 km height region.Cross-field irregularities were observed in the regionof downward gradients, indicating that the verticalHall polarization field was downwards. During normalelectrojet, it is known that the cross-field irregularitiesare observed in the region of upward gradients inthe electron density profiles.

The profiles of the neutral and ion compositionand the electron density, simultaneously measuredby the rocket-borne probes from TERLS duringafternoon hours are used to compute the electrontemperature profile. The result is that the electrontemperature is twice the ion temperature around110 km, the height of the current maximum in theelectrojet. The measurements are made during thetime of counter-electrojet. Another similar set ofmeasurements made during night time when com-pared with day time observations reveal that thenitric oxide concentration at 110 km altitude atnight is higher than during the daytime. This isindicative of a diurnal variation in the nitric oxideconcentration.

With the commissioning of high resolution solardecametric spectroscope in 34-35 MHz range, avariety of new types of solar radio oursts have beenidentified. The "inverted U" type of burst observedfor the first time, has been explained in terms ofthe changes in the direction of the local densitygradient which the exciting radio wave encountersas it traverses the coronal density irregularity.

The geomagnetic field variations at low latitudesduring quiet day time hours are largely attributed tothe ionospheric currents flowing eastward in theE-region. It has been shown that during certainoccasions of partial counter electrojet there may betwo ionospheric currents flowing in different direc-tions at slightly different altitudes within the E-region.

A comparison between equatorial electrojet andinterplanetary plasma parameters shows that thenoon-time electrojet weakens and counter-electrojetintensifies when positive Bx, negative Bz and plasmadensity N increase.

A study of the relationship between solarmagnetic sector structure and geomagnetic Dst showsthat not all sector boundaries give noticeable Dstchanges.

ARYABHATA :- The Solar Planetary PhysicsGroup had put up two scientific payloads on the

first Indian Scientific Satellite - Aryabhata - success-fully launched from a USSR cosmodrome on 19thApril, 1975. Due to a malfunction in the telecommandrelay at the launch phase, i 9 V power could notbe fed to these payloads and these experiments werenot giving any data in the initial orbits of the satel-lite. Subsequently there was a permanent damagein one of the power supply which was common toall scientific experimental packages on-board thesatellite. Hence, the experiments have not yieldedany scientific data.

SOLRAD 11 :- This will be one of the majorprogrammes of the Area for the year 1976-77. Twoidentical satellites, namely SOLRAD 11A and 11B,have been fabricated by the Naval Research Labora-tory (NRL) in USA and launched on 15 March,1976 in a near circular orbit with 1,30,000 km radiusin an approximately ecliptic plane. The Solar PlanetaryPhysics Group is making massive preparations tomonitor the telemetry signals from these satellites atthe Physical Research Laboratory on a routine basis.A steerable antenna with 12.5 x12.5 m9 dimensionscarrying 16 short back-fire elements is under cons-truction for this purpose. The satellites carry instru-mentation to monitor solar fluxes in X-rays, E.U.V.and U.V. ranges in addition to particle and solarwind measurements. Between PRL and NRL nearcontinuous monitoring of solar radiations within andoutside the earth's magnetosphere would be avai-lable. These measurements are expected to augmentsubstantially the ground, rocket and satellite-borneprogramme on Solar and Planetary Physics in theLaboratory.

A retarding potential analyser for measuring thesupra-thermal electron flux in the daytime ionospherewas designed and the bench tests were completedsatisfactorily. A payload will be constructed for flighton an RH-560 test rocket.

An ultra violet sensor for measurement of ozonedensities has been designed. This instrument will formpart of the ISRO-HMS (USSR) collaborative pro-gramme during 1976-77 and 1977-78 for stratos-phere-mesosphere interaction studies.

Instrumentation for tracking Li release fromrockets during daytime is completed and successfullaboratory tests are over. This instrument is beingused in a rocket campaign scheduled for April 1976.

INFRARED ASTRONOMY

This is a new area which has come into exis-tence from April 1975. There are two sub groups

in this area which plan to use (1) optical techniquesin the near infrared and (2) radio techniques in thecm and mm region.

THEORETICAL PHYSICS

NUCLEAR THEORY

It was conclusively shown that the anti-defor-mation - producing tendency of the two body spinorbit part of the effective interaction plays a crucialrole in determining the spectrum of 1 8 C. This indi-cates the inadequacy of simplified alpha cluster modelfor light nuclei.

A systematic and successful study of the struc-ture and electromagnetic transitions in the f-p shellwithin the framework of Deformed ConfigurationMixing Shell Model and Projected Hartree FockBogoliubov calculations has been completed.

A new seven parameter mass formula based onsingle particle picture of the nucleus has beensuggested. The mass formula is based on the factthat in this case a many particle wave functionbelongs to a one dimensional representation of adirect sum unitary group defined by the single particlestates. The energy of the state can then be expressedin terms of scalar operators of the group.

PLASMA THEORY

In the frame-work of Einstein-Cartan theory anequation of state for a system with cylindricalsymmetry and in the presence of magnetic field hasbeen obtained and it is found that the equation ofstate is an explicit function of the magnetic field. Anumerical computation of the trajectory of particlesin the presence of whistler mode waves of equalamplitudes have been carried out for the first time,ind we found that the concept of trapping becomesquite involved. Non-linear ion-acoustic waves whichin the absence of collisions are modulationally stablein the long wave length limit are shown to be un-stable in the presence of collisions.

The theoretical physics area played an importantrole in the development of research programmes ofthe Laboratory Astrophysics area.

LABORATORY PLASMA AND ASTROPHYSICS

EXPERIMENTAL PLASMA PHYSICS

Cross-field instability excited in a collisionalplasma by density gradient and electric field perpen-dicular to a magnetic field was observed and its

spectral characteristics identified. Experiments revealthat nonlinear wave interaction plays a significantrole in the saturation of the instability.

Nonlinear ion wave experiments were initiatedduring Prof. Igor Alexeff's visit. A large volumequiescent double plasma machine was built forconducting experiments on solitons and ion beam-plasma interaction. Breaking up of a large amplituderarefaction wave was observed.

Significant technical achievements include 1)setting up of a large volume ultra high vacuumsystem capable of reaching 10~9 torr for studies relat-ed to electron trapping in a mirror field 2) Buildinga 15 kilojoule energy storage capacitor bank withatmospheric pressure triggered spark gaps andnecessary electronics.

LABORATORY ASTROPHYSICS

A new scientific activity to carry out studies ofphoto-molecular interactions in atoms and moleculesof astrophysical importance, has been started thisyear with the expertise in U.V. techniques developedby the rocket aeronomy group.

The interaction of UV photons with planetarygases leads to phenomena like photoionization,photoabsorption, fluorescence, etc. A knowledge ofthe cross-section for such processes is required fora quantitative understanding of the physical processesin the planetary and stellar atmospheres.

Apart from the interest of obtaining such datafor application to processes in the planetary atmos-pheres, photoelectron spectroscopy provides a usefultool for studying the basic physics of molecules. Itcan yield important information about molecularorbitals by determining quantitative values for theirbinding energies and also by giving informationabout their chemical bonding characteristics. It alsomakes possible the exploration of inner shell orbitalenergies.

At present the expriments to study U.V. photo-electron spectroscopy are being set up. Part of thesystem consisting of a powerful ultraviolet sourcecalled BRV source, a photoelectron spectrometer andan UV monochromator is already near completion.It is planned to work with UV photons of wave-lengths down to about 300A. Another experimentaltechnique which indirectly yields information aboutthe photoionization process is electron energy-lossspectroscopy. The feasibility of this type of spec-troscopy is being investigated.

6

GEOCOSMOPHYSICS

Measurements on plastic detectors from SKYLABmissions have provided new information on thecharge composition and energy spectrum of lowenergy particles in the near environment of theearth. The observed fluences of these particlesrequire a hitherto unknown mechanism of acceleration.

With a new technique for studying VVH andVH nuclei accelerated in solar flares and recordedon lunar soil samples, the energy dependence ofcharge composition of solar flare particles has beendemonstrated.

A novel technique developed for nondestructive,but high resolution measurements of A1 -26 withdepth in lunar rocks has shown no variation (lessthan 20%) in the solar activity during the last millionyears.

Microcrater population, fossil track density,grainsize distribution, and other studies on lunarmaterial and meteorites suggest that the latter haveformed in less energetic collisional events lendingsupport to the hypothesis of their origin on asteroidalsurfaces.

A total of about 45 kg of a stone meteroritewhich fell near Dhajala, Gujarat (28 January 1976)was recovered immediately aftsr-»=fa& It has beenanalysed for cosmic ray produced nuclides, elementalcomposition, exposure age, fossil track records, etc.The 5.5 day Mn-52 isotope was clearly identified.

Systematic and detailed measurements of thedistribution, mineralogy and radioisotope concentra-tions in particulate matter retrieved from very largevolumes of surface and deep water of Atlantic andPacific Oceans have been carried out. The resultsbear importantly on (i) latitudinal variations in theproductivity of different marine organisms, (ii) in-situ dissolution rate of CaCO3 and opal in deepwaters, (iii) the major processes regulating the con-centrations of radionuclides and trace elements in

seawater, and (iv) settling velocities of particles inseawater.

ARCHAEOLOGY

Important 1 4C dates have been obtained onpollen bearing sediments of Toshmaidan in Kashmirwhich have helped in delineating the climatic se-quence of the region. These dates indicate thatdeglaaiation in this region started around 14,000years B.P. These are the first dates from this areacovering a three-fold climatic sequence, in confor-mity with global trends.

Dating of Painted Grey Ware Culture indicatesthat it extended to the 3rd century B.C. Some datesfrom Bakhera, M.P. and Koldihawa, U.P. - too oldfor the suggested Chalcolithic association - haveindicated probability of some hitherto unknown basalculture in these regions. Oldest dates from thesesites obtained are 5310 B.C. and 5440 B.C. res-pectively. These in association with rice fromKoldihawa indicate the earliest occurence of ricein India.

As part of the programme for the study ofpalaeoclimate on N-W India samples of quartzgrains in Saurashtra miliolites were studied usingScanning Electron Microscope. All the studies clea-rly show that these grains were transported to theirfinal place of deposition by wind.

Microscopic and radiographic studies weredeveloped and carried out on neolithic pots fromKashmir to reconstruct neolithic ceramic technology.

HYDROLOGY

A digital model of the mechanism of soil mois-ture transport in the unsaturated zone has beendeveloped and tested using data from alluvial plainsof U.P., Haryana and Punjab obtained by usingartificial tritium as a tracer.

Work on the Sabarmati cell is being continued;very valuable data are emerging from these studieson the amount and quality of underground water.

ResearchProgrammes

SOLAR AND PLANETARY PHYSICS

IONOSPHERIC STUDIES BY ROCKET EXPERIMENTS FROM THUMBA{TERLS)

Co-ordinated study of ionospheric processes in equatorialionosphere

A co-ordinated rocket launching programme was jointly undertakenby ISRO and SRC (UK) for the study of Ionospheric processes in theequatorial ionosphere; PRL scientists participated on the ISRO side.Priliminary results obtained during this experiment were presented at aSymposium on Upper Atmosphere Measurements at VERNA 1975 andthese include the first observations on daytime winds over Thumbaobtained with the Lithium release technique. The results show over-whelming dominance of the semidiurnal component at all altitudes incontradiction to theoretical predictions which favour diurnal tide at low,equatorial latitudes in the thermosphere. Harmonic dial of winds showclockwise rotation with time upto 120 km whereas above 120 km, it becomesanticlockwise. Also, calculations based on the actual observed electrondensity profiles on that day and the daytime winds show significantcontribution of local neutral wind dynamo to the electrojet strength. Wesuggest that the "localised reversed electrojet" may purely be the effectof neutral winds.

( D. Rees, P. D. Bhavsar, J. N. Desai, S. P. Gupta and P. Hounce).

Measurements of ion-neutral composition and electron densitySimultaneous measurements of ion and neutral composition, and electrondensity made from Thumba are used to determine the ionisation recom-bination cycle and electron temperature? in the lower thermosphere.The electron temperature is found to be equal to that of the ion tempe-rature around 150 km, while around 110 km the electron temperature istwice as large as the ion temperature. The measurements were made inthe afternoon'while a counter electrojet was in progress. The night-timeflight showed good fitting of the ionisation and recombination rates ataltitudes where the helium line is expected to produce the night-timeionisation.

Night-time nitric oxide concentration derived from ion and electrondensity measurements over Thumba is found to be not less than3 x 1 0 7 cc around 110 km. This is more than that observed during daytime at the same location suggesting a diurnal variation in this concen-tration.

( J . S. Shirke, R. Sridharan, S. R. Das, PRL; A. A. Pokhunkov,V. K. Semenov and A. D. Danilov, HMS, USSR ).

Winds in the lower thermosphere as measured by vapour cloudrelease

A study of the thermospheric winds observed at twilight based onchemical release experiments carried out at 15 different sites covering58°N to 32°S, including results obtained by PRL scientists from Thumba,were presented at the Symposum on Upper Atmosphere Measurementsat VERNA, 1975. The study shows that, in the equatorial region, below30* latitude, there is a regular seasonal circulation with a westerly flowin 120-140 km region and easterly flow in 140-180 km region.

(P. D. Bhavsar, M. S. Narayanan and J. N. Desai)

8

Plasma irregularities in the electrojet

(a) Normal electrojetThe study with the Langmuir probe during

morning hours before reversals shows that the irregu-larities due to two stream instability occasionally occurduring the period in the altitude range of 100 to110 km. The amplitude of irregularities due to two-stream instability during daytime were found to varywith altitude. Some of these variations can beexplained on the basis ot neutral wind shears nor-mally observed in this region. The irregularities dueto crossfield instability mechanism were found to havemaximum amplitude around 91 km, while the maxi-mum amplitude region calculated from the lineartheory comes out to be 97 km. The spectral indexof 30-300 m irregularities generated due to crossfield instability mechanism was found to be -2.2as compared to -3.5 predicted from the theory ofcrossfield instability mechanism.

(Satya Prakash, T. R. Rao and H. S. S. Sinha )

(b) Counter-electrojet

Blanketting type of sporadic E layers wereobserved with rocket-borne Langmuir probe on tworocket launches during the presence of counter-electrojet. The blanketting layer was observed below100 km where the efficiency of the wind shears forthe ion convergence is quite low. On one of thelaunches Es was observed at 95 km while on theother it was observed at 90 km. The lower portionof Es was much sharper than the upper portion.Numerical studies of the reversed electric fields in theelectron density distribution indicated that the sharplayer of ionisation cannot be produced by electricfields alone. Irregularities which can be identified asdue to crossfield instability mechanism were observedin the upper portion of Es where gradients in electrondensity are downwards. This indicates that theambient electric fields are from east-to-west at leastupto 110 km. During one of the counter-electrojetflights, unusually large irregularities due to neutralturbulence were observed in the altitude range of60-70 km.

Electric and magnetic fields

The major event of this year is the launching ofthe payloads instrumented by us for measurement ofeleotric and magnetic fields and their fluctuationswithin the electrojet. In all five payloads carryingAC/DC electric field probes and scalar/vector rubi-dium magnetometers were launched in Feb. 1975.Of these, very good data were recovered from onevector rubidium magnetometer, a total field magne-tometer and an AC electric field probe. Data reduc-tion and analysis of data from these three successfulflights are in progress.

Meanwhile, the data from previous Indo-UKrubidium magnetometer launchings of 1972 havebeen analysed. It is found that the form of thevertical distribution of the current near the center ofthe equatorial electroject does not change significantlyfrom day to day even when the total intensityincreases by as much as a factor of two. This is animportant result. Some theoretical workers likeRogister and T. Sato expect a change of currentdistribution near the center of the electrojet on highjet days due to two stream instability stabilisation.Our results show no such change.

The data from electric field probes we haveflown so far indicates significant static electric fieldfluctuations in the region of the electrojet.

The data from ihe rocket flight P-60 which waslaunched during the early phase of a magnetic stormhas been analysed. It is concluded that in the even-ing sector and during the earlier phase of the magneticstorm where a partial ring current is building upoverhead, the equatorial ionospheric contribution tothe magnetic depression observed at the groundlevel is negligible as compared to that of magneto-spheric contribution. This fact must be taken noteof while interpreting equatorial enhancements ofvarious stages of magnetic storms observed by severalworkers.

(T. S. G. Sastry and S. Sampath )

(Satya Prakash, T. R. Rao and H. S. S. Sinha ) Study of plasma resonances

(c) Horizontal scale sizesData from a rocket-borne propagation experi-

ment are used to yield the east-west horizontal scalesizes of the irregularities in the equatorial ionosphere.It is found that the scale size increases from 50 mat 86 km to 130 m at 92 km.

(J . S. Shirke and S. N. Pradhan )

It has been possible to detect several resonancesin the ionosphere with the new resonance probedeveloped at PRL. It has been found that the ampli-tude and frequency of the strongest resonance(believed to be the upper hybrid resonance) isdependent on the orientation of the rocket withrespect to the ambient magnetic field. Such a studyhas been possible because of the sharpness of the

resonance and the high resolution in frequencyachieved in our system.

(Satya Prakash and T. R. Rao )

Scattered Lyman alpha measurements

D t̂a from Lyman alpha experiment conductedon a petrel rocket flight during the morning twilightof 9th Feb. 1975 at Thumba have been analysed toobtain results on the direct as well as scatteredLyman alpha fluxes on the height range 80-140 kmin the atmosphere. The scattered Lyman alpha radi-ation was measured over a range of zenith angles60s to 90°. An interesting systematic zenith anglevariation of 30% was found to exist in this rangeof zenith angles. The measured flux was 3.1 KR ±20% near 90° zenith angle.

( B. H. Subbaraya, P. N. Pa reek, Satya Prakash andVijaykumar)

Measurement of molecular oxygen concentra-trations

Molecular oxygen concentrations measured atmesospheric and lower thermospheric heights overThumba using the UV absorption technique appearto show an interrelationship with the electrojetcurrents. Study is in progress to delineate the natureof this relationship and its significance to the equa-torial atmosphere.

( B. H. Subbaraya )

GROUND-BASED STUDIES OF THE IONOSPHERE

Lower IonosphereMesospheric nitric oxide concentration is shown

to be linked with N(aD) formation at higher alti-tudes, which in turn is proportional to electron densitynear F region peak. This is shown to produce a geo-magnetic anomaly in mesospheric ionisation similarto the Appleton anomaly in F region ionisation(J. S. Shirke and S. Ganguly, [Uni. of Lancaster, U. K])

Inverse frequency dependence of absorption ofradio waves in the ionosphere near the dip equatoris shown to be a manifestation of the geomagneticanomaly in the D region.

( J . S. Shirke)

Partial reflection studies show a factor of 2-4larger electron densities at Ahmedabad than at midlatitudes for the same solar zenith angle conditions.

( J . S. Shirke and S. N. Pradhan )

The effects of collision on the real and imaginarycomponents of the refractive index of radio wavespropagating in the lower ionosphere have beencarried out using generalised magnetoionic formula-tion for different locations. The reflection as well asabsorption coefficients are shown to be larger forthe ordinary mode compared to the extraordinarymode in the collision dominated region.

( J . S. Shirke and S. N. Pradhan )

Winter anomaly in ionospheric absorption ofradio waves is attributed to downward transport ofmetallic ions at mid latitudes. Upward transport ofsuch ions at low and equatorial latitudes is shownto be producing a cusp and high type sporadic Elayers.

( J . S. Shirke)

BACKSCATTER RADAR STUDIES OF THEEQUATORIAL ELECTROJET

The study of the electrojet irregularities withthe backscatter radar at Thumba shows that duringmorning and evening reversals the electrojet currentsflow in altitude region 6 to 8 km higher than duringother periods.

The backscatter radar studies at Thumba showthat the nature of electric fields in E-region at Thumbaare similar to those at Jicamarca ( Peru ).

The hysterisis in the backscatter radar signalversus the earth's magnetic field indicates the pre-sence of current in the region above 110 km.

The study of the drifts of electrons in E and Fregions over Jicamarca (Peru) shows that theelectric fields in the F-region are usually higher thanthe fields in the E-region. The ratio of the electricfields in the E and F regions is smallest during thepost-reversal periods.

(Satya Prakash and P. Muralikrishna )

GEOMAGNETISM

An attempt was made to study the relationshipbetween equatorial electrojet and interplanetaryplasma parameters. It was noticed that noon-timeelectrojet weakens and counter-electrojet intensifieswhen positive Bx, negative Bz and plasma densityN increase.

Relationship between solar magnetic sectorstructure and geomagnetic Dst was studied. It wasfound that not all sector boundaries gave noticableDst changes.

(R. P. Kane)

10

The equatorial type of Es is shown to disappear,not when the geomagnetic H field decreases belowthe night time level but when the latitudinal gradientof A H is negative towards the equator. Even duringsevere geomagnetic storms, Es-q disappears pre-cisely at the time when A H at the equatorial minusA H at tropical latitudes becomes negative eventhough absolute A H at the equator may be signi-ficantly positive. These results have led to a proposalof a partial counter-electrojet system; two ionosphericcurrents are suggested to be flowing simultaneouslyover the magnetic equator at slightly differentheights. The equatorial Sq current is suggested toflow at 107 km and the counter electrojet current isslightly lower, at 100 km. The observed A H atground is the net effect of the two currents.

Blanketting Es is shown to appear on equatorialionograms only during periods of low electrojetcurrent or during periods of counter electrojet current.This type of Es is suggested to be due to accumula-tion of plasma by the movements of heavy metalicions from low latitude stations by neutral wind flow-ing towards the equator.

A detailed account of the diurnal, seasonaland solar cycle variations of the counter-electrojetphenomena observed at all the equatorial stationsin the world viz. Huancayo, Freetown, Addis Ababa,Kodaikanal and Davao has been published. It hasbeen shown that the counter-electrojet occurs onlyat regions very close to the magnetic equator, verylocalised having short longitudinal extent and isinversely correlated to solar activity.

The main cause of the counter electrojet hasbeen suggested to be of lunar tidal origin, but shortperiod occurrences of counter current is shown tocorrelate more or less with the reversal of interpla-netary magnetic field from southward to northwarddirection. This is explained in terms of the impositionof V x B field generated by the solar wind interactingwith the earth's magnetic field such that this imposi-tion over the entire earth affects predominantly theequatorial region.

The geomagnetic storm sudden commence-ments (SSC) are generally considered to be due tothe compression of the earth's magnetic field byinteracting solar plasma and thus the seat of geo-magnetic storm effects has been considered to beat the magnetopause. The geomagnetic field observ-ed at equatorial stations during geomagnetic stormsdoes not identify the height range whore sourceslie. A comparison of the strength of trans-equatorial

VHF signals scattered by E-regicn irregularities andthe geomagnetic field at stations below the mid-point of the circuits, shows that the shape of suddencommencement changes and the intensity fluctua-tions have very faithful resemblance. Thus thenegative as well as positive changes in the SSCfluctuations are shown to be caused by the corres-ponding changes in the E-region currents over themagnetic equator. These results have a significantimportance on the understanding of the completegeomagnetic storm phenomenon.

( R. G. Rastogi )

Another evidence of the westward currents inthe equatorial region during the day time has beenproduced by the study of solar flare effects (sfe) ingeomagnetic field at low latitudes. The sfe duringa strong electrojet day produce progressively largerA H near the equator. The sfe during a completecounter electrojet day produce negative A H nearthe equator and positive A H at regions outside theelectrojet region. During the partial counter electrojetday A H may be positive at all low latitude stationsbut its magnitude would be smaller at stations nearthe equator than at stations outside the belt ofelectrojet current. The extra ionisation from the sunduring these events increasos the normal Sq currentat 107 km altitude but this may be counter balancedby the westward current flowing at 100 km resultingin a smaller sfe at equator than outside the electrojetbelt.

( R. G. Rastogi, M. R. Deshpande and N. S. Sastri )

It has been earlier shown that the irregularitiesassociated with the q type of Es layer near themagnetic equator are the cross-field (or gradient)irregularities. The life time of theso irregularities atE-region height has been estimated to be less thanone minute. Experimental evidence of this has beenpresented by showing that Es-q layer can suddenlydisappear and reappear between two records ofvertical ionospheric soundings taken at an intervalof only one minute.

( R. G. Rastogi, M. R. Deshpande and A. Sen )

F REGION STUDIES

The annual variation in the maximum F regionionisation NmF2 at low latitudes is shown to exhibita geomagnetic control with complimentary behaviourat magnetically conjugate latitudes.

Annual and semiannual variations in NmF2,the maximum F region ionisation, are explainable interms of global variation of atomic oxygen and

11

plasma transport between conjugate latitudes as wellas from the dip equator to low latitudes. This workis being continued to evolve a quantitative modelto explain the observed features.

(S. S. Degaonkar and J. S. Shirke)

The day-to-day variability of ionospheric totalelectron content was studied. Fluctuations as largeas ± 50% in magnitude and + 4 hours in the timeof maximum were observed even on quiet days.

(R. P. Kane)

The upward moving kink detected for the firsttime on Thumba ionograms has been shown tooccur at other equatorial stations and the verticalvelocity derived from its height variation is shownto be comparable to that measured by VHF back-scatter radar at Jicamarca.

( R. G. Rastogi and K. N. Iyer)

TOPSIDE SOUNDING

Lunar effect on the equatorial ionisation ledgesOne of the major results that has come out from

the topside sounding has been the frequent occur-rence of ionisation ledges in the topside ionosphere.More than 200 occurrences of ionisation ledges havebeen studied from the data recorded at Ahmedabadduring the years 1972-75. ft is found that the ledgeoccurrence has lunar age dependence. Both theoccurrence and intensity distribution of ionisationledges showed two peaks around 0300 and 1500hour lunar age. The existence of these peaks wasexplained in the terms of the modulation of thediurnal solar electric field by the semi-diurnal lunartidal electric field.

( R. Raghavarao and P. Sharma )

lonisation ledge and the counter-electrojet

It was found that on 70 per cent occasions outof about 170 ionisation ledge observations on mag-netically undisturbed days, the counter-electrojet alsooccurred in the E region (as revealed by the hori-zontal magnetic field data at Trivandrum and Alibag).This significantly high correlation in the day to dayoccurrence of the ledge and the counter electrojetand also the same or similar morphological featuresin their occurrence (viz., more frequent occurrence ofboth in solar minimum activity period, same lunarage dependence etc.) indicate that the two pheno-mena could have been caused by the same source.As neutral anomaly is known to be the cause for

the ledge formation in the topside, it was suggestedthat the same anomaly might also cause the counter-electrojet at the E region height.

(R. Raghavarao and P. Sharma )

lonisation ledge - A trace for cross equatorialwinds

Intensity contours of the ionisation ledge weredrawn to show the horizontal and vertical extent ofthe ledge. The structures were found to be symmetricin horizontal extent (around the magnetic equator)during equinox period and assymmetric during sols-tice period. During solstice, the spatial structures arefound to be physically shitted to the winter hemis-phere. These observations showed, for the first time,an evidence for the existence of cross-equatorial(summer to winter) neutral winds at the thermos-pheric altitudes. The wind magnitudes, calculatedfrom the shift of the ledge structures into the winterhemisphere were found to be of the same order ashypothesised for explaining the observed solsticeasymmetry of the ionisation anomaly crests in thenumerical simulations by various workers. Thus, theionisation ledge provides a tracer for determinationof the cross equatorial winds.

( R. Raghavarao, P. Sharma and M. R. Sivaraman )

Structure of plasmasphere

Studies of the earth's plasmasphere using "insitu" probe observations from polar orbiting satellitesare under way. A major problem is to understandthe relationship between electron density, electrontemperature and ion composition in the 1000-3500 km altitude region. Some interesting resultshave been obtained on the electron density - electrontemperature relationship, the occurrence of nighttime mid-latitude electron density peaks, the beha-viour of the plasma trough in the dawn and dusksectors, and the response of the plasma trough tomagentic storms.

(G. Rajaram, A. C. Das and R. G. Rastogi)

RADIO BEACON EXPERIMENTS

The major task performed by the group interest-ed in radio beacon experiments at PRL has been todevelop simple polarimeters which can be used atvarious University Centres in India and also to esta-blish a sophisticated set of experiments at the troughand peak regions of the Appleton anomaly, to under-stand fully the development of the equatorialanomaly in a consolidated way from ground as wellas satellite observations.

12

Total electron content (TEC) studies

A rotating antenna type (Titheridge type) Fara-day recording polarimeter was developed at PRLusing predominantly indigenous materials. This equip-ment consists of a rotating eight element yagi withelectrostatic coupling transformer and preamplifier,convertor and receiver for 137 MHz and finally phasecomparator and recorder. Six such units were deve-loped and installed at the following institutions :

(1) Indian Institute of Geomagnetism, Bombay(2) Andhra University, WaStair

(3) A. V. Parekh Technical Institute, Rajkot

(4) Physical Research Laboratory, Ahmedabad(5) Udaipur University, Udaipur, and

(6) Punjabi University, Patiala

Further, personnel from these stations were trainedat PRL and the observations have been satisfactorilystarted at all the locations.

( R. G. Rastogi, M. R. Deshpande, Bansidhar and

N. M. Vadher)

Combining the records of Faraday Fadings of 40MHz radio beacons from satellites BE-B and BE-Cfrom Ahmedabad and Kodaikanal, it has been shownthat the total electron content (TEC) at Kodaikanalreaches the maximum value at about 1500 hr localtime without any indication of a decrease aroundnoon oven though the maximum electron density intho F2 region, NmF2, shows a very distinct bite-outaround midday. On the same days the latitudinalvariation of TEC did show a decrease around theequator and a peak around latitudes of Ahmedabad.Thus while NmF2 shows both latitudinal as well asdiurnal anomaly at low latitudes, the TEC showsonly the latitudinal but not the diurnal anomaly.Thus a significant contribution of the neutral densityanomaly is suggested in the production of equatorialanomalies in the F2 region.

(R. G. Rastogi, K. N. Iyer and J. C. Bhattacharyya)

The countours of TEC at low latitudes in Indiacovering the latitudes 16° N to 40° N have beenconstructed tor each season of lew as well as highsunspot years using the Faraday fading records ofbeacons from BE-B and BE-C satellites recorded atAhmedabad. These are expected to be useful forderiving the system loss and group delay errors forSatellite Communication Systems in Indian zone.( R. G. Rastogi, R. P. Sharma, K. N. Iyer and V.

Shodhan)

The scintillation of radio beacons on 40 MHzfrom BE-B and BE-C satellites recorded at Thumbahas been shown to be closely associated with thespread F at Thumba. The belt of intense scintillationof about 1000 km width is shown to be centredwithin about 5° from the magnetic equator.

( R. G. Rastogi and H. Chandra )

The beacon signals from a geostationary satel-lite were recorded at Ahmedabad for the first time byusing 136.989 MHz radio waves from SYNCOM III.The integrated production rate was calculated foran overhead sun from the temporal change of TECand the values showed general agreement with thevalues obtained by other workers.

( R. G. Rastogi and M. R. Deshpande)

Faraday rotation and group delay studies

At the Astronomy Centre, Ootacumund we haveinstalled a sophisticated ATS-6 receiving stationloaned by NOAA Laboratories Boulder, U.S.A. Theequipment consists of a massive antenna system,a single element short back-fire antenna for 40MHz, a four element short back-fire antenna for140 MHz and eight element short back-fire antennafor 360 MHz. The main equipment records orthogonalcomponents as well as total amplitudes of radiobeacons on 40, 140 and 360 MHz. This also recordsgroup delay on 1 MHz and 0.1 MHz modulation on40 MHz with respect to 360 MHz. Further 1 MHzmodulation group delay on 140 MHz isrecorded with respect to 360 MHz. We also recorddifferential Faraday rotation on 40 and 140 MHzwith respect to 360 MHz. Each of these data aredigitized and recorded on a tape recorder. Due tosome malfunction of the computer, the data at presentare recorded on a multi-channel strip chart recorder.

The observations of multi-station 140 MHzFaraday fading have already shown that the diurnalvariation of the electron content at all the stations,whether within the electrojet or outside, has a mini-mum around sunrise hours and maximum around1500 hr. There is no bite-out of the TEC at theequator even on days when a strong latitudinalanomaly is present in TEC. A detailed comparisonof all the records has revealed interesting featuresof travelling ionospheric disturbances, the velocities,direction and the extent of their movements. Thecharacteristics of the TIDs are being studied duringvarying geomagnetic and solar activity periods.

13

The effects of solar flares and geomagneticdisturbances have been clearly identified on theserecords. Even a preliminary analysis of the recordsat Ootacamund has revealed many interesting fea-tures. The occurrence of amplitude scintillations isnot confined to night time hours, but significantscintillations are seen during day light hours evenaround noon. It is suggested that the blanketting typeof Es, very common in Indian zone during low sun-spot years, may be the cause of the day timescintillations.

According to the observations available fromnon-equatorial stations, scintillations are supposedto be inversely proportional to the frequency, i.e.,the higher frequencies are less affected by theionospheric irregularities than the lower frequencies.The observations at Ootacamund reveal that duringnight time this law is generally invalid. Scintillalionsare very strong on 360 MHz and on occasions evenexceed those on 40 MHz. A detailed study of thisphenomenon in relation to the ionospheric condi-tions seen by bottom side ionosonde is beingconducted.

Using the simultaneous observations of totalelectron content calculated by Faraday rotation andthe group delay, exospheric electron content hasbeen derived and has been found to have a signifi-cant relation to the ionospheric electron content.With these high resolution observations of differentparameters it has been possible to study phasescintillations of radio waves traversing the ionosphereand then it is found that in the equatorial region thesescintillations are at times of very significant magni-tude and phase variation often exceeds ono radian.Effects of magnetic storms are being studied in detailin relation to the variations of the ground as wellas interplanetary magnetic field.

(R. G. Rastogi, M. R. Deshpande, G. Rajaram,A. C. Das, A. Sen, G. Sethia and H. 0. Vats)

OPTICAL AERONOMY

Observations of Night Airglow for OH (7-2 )band at 6860 A, 6300 A 01, 5893 A Na, 5577 A 01and 5200 A Nl were made at Cape Comorin verynear to the magnetic equator during December 1971 -February 1972. Simultaneous observations were alsomade at Mt. Abu. 6300 A and 5200 A showeddifferent types of enhancement at the transit of acelestial X ray source. 5577 A and OH showedanticovariation at both places but with a lag. 5577A in winter at Mt. Abu was weak while the same

at Cape Comorin was enhanced. It is postulatedthat this could be due to tho transport of atomicoxygen in the 100 km region ovar these latitudes.

(V. R. Rao and P. V. Kulkarni)

The 6300 A Ol night airglow emission fromMt. Abu (24° 6N ) covering 7.5° latitude in alldirections with a scanning photometer is connectedwith the ionospheric parameters measured fromAhmedabad (23° N ) and Delhi (29° N ). It wasfound that intensity of 6300 A radiation varies in-versly with the F region height. Even during thespread F condition the relation holds good. East-West oriented tropical 6300 A arc is identified; itssouthward movement in a typical case is esti-mated to be 200 m/sec. East—West movementof the isophotes with similar velocities is observedon a few occasions. It is suggested that while thesouthward movement may be due to the movementof the F region tropical anomaly, the east-westmovement may be due to the travelling ionosphericdisturbances.

(V. R. Rao and P. V. Kulkarni)

A new experimental method is used to determinethe neutral temperature of the upper atmosphere inthe 90 km region by monitoring OH night airglow.The photoelectric photometer measures one line inthe P branch of the OH ( 7 - 2 ) band and the totalintensity of the R branch. The ratio of the twointensities gives the temperature. The instrument isbuilt, field tested, and regular data is being received.Preliminary results show that the method is sensitiveto the changes in temperature in the 90 km region.

( P. V. Kulkarni and Nita H. Majmudar)

Geomagnetic control on the equatorial anomalyin the F region is shown from 6300 A night airglowobservations. During the blackout period in December1971 excellent sets of observations were taken.During that period a spell of "active-quiet-active"magnetic activity was recorded. It is shown that,during high solar activity period but during magneti-cally quiet nights the equatorial anomaly is welldeveloped during early hours of night and movestowards south. On magnetically disturbed nights thearc is poorly developed, fades before midnight andmoves slightly towards south. The work shows that6300 A night airglow measurements could be reliablyused for monitoring equatorial anomaly.

( P. V. Kulkami)

14

Night airglow doppler temperatures for 6300A 01 line were observed for few days during February1976. Because of the preparations for the Lithiumrelease experiment (scheduled in April 1976) andassociated instrumentation for tracking daytimerelease of Lithium, extended observations could notbe undertaken.

( J . N. Desai)

RADIO ASTRONOMY

Solar radio astronomy

The main emphasis of research in solar radioastronomy during 1975-76 has been to gain betterunderstanding of decametric radio burst phenomenawhiuh are of crucial importance from the point ofview of coronal plasma physics. Major effort wasmade to install an array of 16 Vagi antennas arrangedin the form of a cross in order to (a) increase thesensitivity of the high resolution solar radio spectros-cope ( 3 5 - 3 4 MHz), and (b) incorporate highspeed polarization capability along with the spectralinformation of short-lived, narrow-band bursts. Thisfast, sensitive instrument was commissioned from July1975. An intense solar decametric noise storm wasrecorded in November 1975, with the help of thisspectroscope, and has revealed some new spectralfeatures of bursts, the physical significance of whichis relevant to the structure of coronal electron densityirregularities.

The Solar radio spectroscope has been modifiedto work from 45 to 25 MHz with frequency resolutionof 15 kHz and scanning rate of 10 Hz. This wouldserve as a back-up for the high resolution spectro-scope ( 3 5 - 3 4 MHz) in order to unambiguouslyidentify the spectral type of bursts, and also to detecttype ll-shock waves in the outer corona. Absolutecalibration of microwave radiometer at 2.8 GHz hasbeen completed and daily solar flux values with± 3 per cent accuracy are now available.

The time-sharing radio polarimeter used forsolar radio burst work at 35 MHz was modified toreceive ATS-6 beacon transmission at 40 MHz to studythe total columnar electron content upto the satelliteheight. Owing to the low operating frequency (40MHz) of this polarimeter, the Faraday rotation rateis suc^ *>~.ax jt is not necessary to rotate the antennato produce nulls on the satellite field strengthrecordings. The Stokes parameters I, the sum of thetwo orthogonal intensities and Q, their difference,are useful to study scintillations and the total elec-tron content in the ionosphere respectively. Prelimi-

nary results of this experiment pertaining to thescintillation activity before and during magnetic stormin Jr.nuary 1976 were reported in the Solar PlanetaryPhysics Symposium in January 1976.

Linearly polarized ATS-6 transmissions at "0MHz were used to calibrate the time-sharing radiopolarimeter. It was found that the received signalwas not linearly polarized but instead was slightlyelljptically polarized. This was interpreted as due tothe combination at the receiver of a direct wave anda wave specularly reflected from the ground. Theamplitude of the ground-reflected component wasfound to be a function of ground conductivity andof the orientation of the plane of polarization at thepoint of incidence.

( R. V. Bhonsle, S. K. Alurkar and H. S. Sawant)

Collaborative Programmes with (1) SAC and(2) Vedhshala

An 860 MHz Dicka radiometer with 20' para-bolic dish was developed by SAC and installed atPRL premises to study variation in amplitude due toscintillations. This experiment was started in Novem-ber 1975. The qceived field strength was about-73 ±1.5 dbm on the average. Occasionally mildscintillations were observed, sometimes simultane-ously at 40 MHz.

(R. V. Bhonsle, S. K. Alurkar, P. Venat, R. Sharmaand N. S. Nirman )

Three synchronizable digital clocks were deve-loped and delivered to RSMD, SAC. One digitalclock was supplied to TV studio at SAC. A lownoise RF amplifier at 1665 MHz for the detectionof interstellar OH molecule was received fromESCES, SAC.

(R. V. Bhonsle, A. D. Bobra, H. S. Sawant & Sohanlal)

An inter-institutional research programme bet-ween Vedhshala and PRL on "High ResolutionOptical Studies of the Sun," was initiated at theUdaipur Solar Observatory. A communication bet-ween Udaipur and Ahmedabad has been establishedso as to alert radio observers at PRL regardingappearance of new centres of activity on the solardisk.

( R. V. Bhonsle, S. K. Alurkar and N. S. Nirman)

15

Technology Development

An R.F. Exciter at 1 MHz, for ultrasonic cleanerwas developed to deliver 5 watts output to thepiezoelectric element for the Geo-cosmophysics Area.

Wide-band ultrasonic transducers with NPL-made piezoceramic discs were developed at 3 MHz.These were tested using them as a transmit-receivepair. These transducers have potential application inmedical electronics, acoustic holography etc.

( R. V. Bhonsle and N. S. Nirman )

EXTRA GALACTIC RADIO ASTRONOMY

[ terplanetary Scintillations

Fine structure, on the scale of a second of arcor less, in a large number of extragalactic radiosources in the southern sky has been studied byobserving their interplanetary scintillations (IPS).These observations carried out, at 327 MHz usingthe Ooty Radio Telescope, have been combined withthose of northern sources studied at Cambridge tostudy statistical correleations between scintillationproperties and other distance dependent parametersof radio sources. It is shown, for the first time, thata strong correlation exists between scintillation visi-bility, flux density and total angular extent of extra-galactic radio sources. This provides a strong evidencethat weaker sources are located statistically fartheraway than the stronger ones.

It is well known that in almost all strong extra-galactic radio sources multi-component structuresexist over a range of angular sizes from minutes ofarc to milliseconds of arc. We have attempted tostudy the effect of the presence of many componentsof comparable angular size on the measurements ofangular size scintillating component by the usualm-p curve method. It is suggested that the angularsize of compact components found by IPS is weight-ed by different sub-structures in radio sources atdifferent redshifts. Thus the angular size of thescintillating components may not provide good 'rigidrods' for measurement of the deceleration parameterof the universe, as has been done by Hewish andco-workers at Cambridge.

The above work was carried out in collabora-tion with Prof. G. Swarup of TIFR.

( S. M. Bhandari)

COSMIC RAYS, INTERPLANETARY SPACEAND X-RAY ASTRONOMY

Cosmic Ray Studies

The daily variation of cosmic ray intensity wasthoroughly investigated. It was shown that the semi-diurnal component may not be completely explainableon the basis of the current models. For the diurnalcomponent, a special study was made of days onwhich the diffusion seemed non-field-aligned.

( R. P. Kane )

The operation of the multidirectional mesonmonitors was continued. In order to study the shortperiod fluctuations, data were recorded every minuteon punched tape. The conversion of this data tomagnetic tape and further analysis by IBM computerare going on. The studies are expected to reveal thenature of short period fluctuations at higher energies~ 4 0 GeV.

( G. Subramanian )

The super neutron monitor has been disconti-nued. This monitor is going to be installed at RewaUniversity. The data from this monitor for the pastmany years as well as data from a network ofneutron monitors have been analysed and presentedin the form of a thesis. The results clearly indicate thatthe diurnal anisotropy of cosmic radiation can beeasily understood in terms of a simple radial convec-tion and a field aligned diffusion of particles. Furtherthe observations showed that on nearly 20% of daysthe conventional concept of radial convection andanisotropic diffusion parallel to the magnetic field isnot valid, and on these days large magnetic fieldirregularities of scales sizes>4 hours are present.The analysis also indicates the presence of dayshaving large radial cosmic ray gradients (^/10%/AU)in the interplanetary medium.

(A. G. Ana nth and U. R. Rao)

KGF Experiment

The underground mu meson experiment usingneon flash tubes at Kolar Gold Field (KGF) has beendiscontinued. A detailed study of interaction of highenergy muons of average energy 370 GeV withmatter was carried out and the results have beenpublished. A study of the separation between thetwo tracks of pair particles is in progress.

( B. Chowdhuri )

16

X-ray Astronomy

High energy (720 Kev) X-ray observations ofCyg X-1 were made in a balloon flight with a viewto study its flux, energy spectrum, and time varia-tion characteristics. The source was found to exhibitlarge random fluctuations in intensity. Changes byfactors of the order of 3 over time scales of 1 mt.could be detected. Also, for the first time, we wereable to detect spectral changes in time intervals asshort as 20-25 mts.

A critical examination of all the balloon observa-tions made so far on Cyg X-1 at high energies wastaken up to study the long term variability of thissource at energies greater than 20 Kev. Presentlyavailable data reveal that there are two levels ofemission of X-ray intensity of Cyg X-1 at theseenergies and further that there is a correlated modu-lation of intensity at 30 Kov with phase of 5.6 daybinary system for both these states.

( A. K. Jain, U. B. Jayanthi, Kasturi Rangan, U. R. Rao)

INFRARED ASTRONOMY

It is planned to make a near infrared photometerwhich would be fixed with one of the existing 40"telescopes in India. To test the instrument and thesystems, survey of known objects will be taken first.Then unexplored portions of the sky will be surveyed.

( P. V. Kulkami)

Planning of Fourier Transform Spectrometer isundertaken. Systems in software and hardware areunder study. Fabrication will start shortly.

( J. N. Desai)

OH maser sources at 1665-67 MHz will bestudied with a 40 feet antenna.

As a first step 60-channel digital autocorrelatorfor determining power spectrum of interstellar OHemission has been developed. Work is already inprogress in order to expand the autocorrelator to100 channels. This digital autocorrelator has wideapplications in various fields where power spectrumanalysis of time-varying parameters are involved.

A design of the OH radiometer system withpolarized antenna feed for the above antenna isbeing finalised.

(R. V. Bhonsle)

NUCLEAR THEORY

The activities of the group have been concernedwith the following problems :a. Multishell Projected Hartree-Fock Studies of

p-shell nuclei using Skyrme Interaction.b. Deformed Configuration Mixing ShelJ Model

Studies of Nuclei in the sd and fp shells.c. Analysis of Effective Interactions.d. Applications of Group Theoretical and Statistical

Methods of Nuclear Structure.e. Deformation Systematic? of Nuclei with A=70-

80f. Simple Shell Model Studies for N=49 Nuclei

MULTISHELL HARTREE FOCK THEORY :

Structure and Spectra of p-shell nucleiThere have been many attempts to use pheno-

manological forces of the type given by Skyrme toreproduce binding energies, sizes and other intrinsicproperties. The set of parameters involved requiredfor a good agreement with experiments is still notunique. We have used these Skyrme type interactionsto calculate nuclear energy spectra and the transitionand static moments for the first time in the micros-copic formalism of multishell Hartree-Fock projectionand band mixing.

First calculations were done for 1 2 C with den-sity independent Skyrme interaction. It was conclu-sively shown that the two-body spin-orbit part ofthe interaction plays a crucial role in explaining the1 3C spectrum. We conclude that a simplified modellike alpha cluster model would be quite inadequateas the latter cannot take account of the spin-orbitinteraction. Calculations are also carried out for mass8 nuclei.

(S. B. Khadkikar and V. B. Kamble)

Band averaged density dependent interactionThe inclusion of density dependence via a zero

range three-body force in a Skyrme interactionpresents unsurmountable difficulties and catastrophefor structure and spectroscopic calculations. We haveovercome this difficulty by proposing a new variantof density dependence; 'Band averaged densitydependence.' This new version is exactly equivalentto the density dependent Skyrme interaction forspherical nuclei and retains rotational invariance ofthe Hamiltonian for deformed nuclei. Calculationswith this new band averaged density dependentinteraction have been done for nuclei 8Be and 1 9 Cgiving excellent agreement with experimental spectra.

(S. B. Khadkikar and V. B. Kamble)

17

STRUCTURE OF NUCLEI IN 1f-2p SHELL

Electromagnetic Transitions in the fp ShellNuclei

A systematic study of the structure of odd-Anuclei in the fp shell within the framework of De-formed Configuration Mixing Shell Model calcula-tions based on projected Hartree-Fock theory isalmost completed. The spectra and electromagnetictransitions of the odd isotopes of Ti, Cr and Vhave bean calculated. The calculated results are ingood agreement with the experimental ones. Someof the results of the calculations of the branchingratios and lifetimes of states in * 9 V are shown intha figure.

(A. K. Dhar and K. H. Bhatt)

Generator Co-ordinate Calculations for B CNi.

There is recent information available regardingthe low-lying spectrum of 5 0Ni -especially J=0 +

states. An attempt is made to explain these statesin the framework of Generator Co-ordinate formalismusing projected states from the constrained Hartree-Fock intrinsic states. The calculations are done inthe space of full f-p shell with two-body matrix ele-ments obtained by Kuo and Brown. It was found thatthe interaction needs some modification to explainthe excited 0 + states such that the excited 'bands'should be less deformed. Further calculations by amodification of two-body spin-orbit interaction arein progress.

( D. R. Kulkarni, S. B. Khadkikar and S. P. Pandya )

On the Microscopic Description of the YrastStates in Even-even 2p-1f Shell Nuclei

The intrinsic states of even-even Ti, Cr, Fe andNi isotopes were obtained by carrying out Hartree-Fock- Bogolyubov calculations employing a modifiedversion of the Kuo-Brown effective (two-body)interaction. The angular momentum projected spectra,the quadrupole moments of the first excited statesas well as the reduced transition probabilities for E2transitions were calculated and compared with theexperiments. The overall agreement between thecalculated and experimental results is quite good.

(S. K. Sharma)

Shape-mixing in Even-even 2p-1f Shell Nucleiand the Emergence of Anharmonic VibrationLike spectra : An Illustration in 5 3Fe

It was shown that one can understand theapparent shift from rotation to something like an-

harmonic vibration in some 2p-1f shell nuclei interms of the role played by the inclusion of thepairing effects in giving rise to enhanced prolate-oblate shape mixing.

( S. K. Sharma )

On the Angular Momentum Dependence of theVariance of the Projected Hartree-Fock WaveFunctions

We have derived approximate but analytic ex-pressions for the variances * " 8 = ( < C H 3 > ~ < H > 3 )the projected Hartree-Fock (PHF) wave functions.These expressions are used for computing the vari-ances for PHF wave functions in some even-even2p-1f shell nuclei. It is seen that the variances forJ$s6 are usually significantly higher than those forthe states with J < 6 .

(S. K. Sharma and P. E. Mugambi)

Magnetic Moment of 5 7 Ni

In a recent experimental study, the magneticmoment of the ground state of 5 7 Ni has beenmeasured to be equal to /|^/=0.88 + 0.06"^ A,which is only about 45 per cent of the Schmidt value.The significant departure from the Schmidt value isexplained in a microscopic, parameter-free manneremploying the improved effective interactions in the2p-1f shell.

The first-order configuration corrections are foundto explain a large part of the deviation of [*>( M Ni) from the Schmidt value, but there still remainsa discrepancy of approximately 0.32 U/h. The overallsecond-order correction to u, is seen to be 0.43 p N .The agreement between the calculated and theobserved value of the magnetic moment is thusreasonably good.

An analysis of the contributions of the varioustypes of graphs involved in the second-order calcula-tion reveals that a significant fraction o f A u ' ( 9 )

arises from the core wave function renormalization.The 'dequenching' of the magnetic moment in 5 TNiis seen to arise mainly from Tamm-Dancoff typegraphs.

( S. K. Sharma )

EFFECTIVE INTERACTION

Deformation Producing Tendency of (d 3 / S - f 7 / 3 )Empirical Effective Interaction.

The effective matrix elements in the ( d 3 / s -f 7 / a ) 3 configuration have been recently defined bySchiffer et al and Cline et al [ Phys. Rev. C3, p.

L18

1976 (1971) ,nd Ann. Phys. 66, p. 546 (1971) ]assuming shell closures for 3 a S and 4:0Ca. We haveattempted to verify whether this empirically deduced(d3 2 - f 7 , 3 ) 9 interaction permits the d 3 / 2 shell toremain closed when nucleons are added to *°Ca.It is found that the Schiffer interaction gives rise toground Ftates of the f7/3 shell nuclei in which thed g / 2 orbit is completely filled. However, that inter-action overbinds 40Ca. If the centroid of the (d a / 3 ) 2

interaction is modified to fit the 40Ca binding energy,the ground states of 48Ca and 5aFe become de-formed and the d 3 / a orbit is not completely filled.

(D. P. Ahalpara and K. H. Bhatt)

Semi-empirical Trimming ofactions in fp Shell :

Effective Inter-

Effective interactions are complex. There are alarge number of matrix elements. The number of(fp)n states is large, and complete shell model calcu-lations are not yet feasible. It is therefore difficult totest whether an effective interaction derived for thefull fp shell space is good in the sense that thespectral and other properties calculated in the fullspace are in agreement with the experimental results.The remarkable f 7 2 subshell closure tendencyobserved empirically when coupled with deformedHartree-Fock calculations within the fp shell, providesa useful check on some general features of theeffective interaction. It is observed that the require-ment of the f7/a sub-shell closure at N=28 togetherwith that of fitting the single hole-particle separa-tion energies in 5 5>51Ni implies that in addition toreducing the ( f 7 / 8 ) 2 attraction, the field producingmatrix elements<f7/3 ^7/3 | Vj f7 / 3 j > of the KBinteraction should be made weaker. In general itappears that a proper effective interaction within thefp shell should have a weaker deformation producingtendency than that of the KB interaction.

(A. K. Dhar and K. H. Bhatt)

GROUP THEORETICAL AND STATISTICAL

STUDIES OF NUCLEI AND ATOMS

Response Curves for a Nuclear System in theDistribution Method.

The response of a nuclear system to an externalmultipole field (quadrupoie for example) is studiedin the spectral distribution method, the motivationbeing that we can then include effects of configura-tion mixing or correlations which are not taken

account of in the usual !!artree-Fock approach tothe problem. Calculations are carried out for nucleiin the space of sd-shell by evaluating averages ofthe Hamiltonian H and H3 over configurations definedby the quadrupoie moment. The results compare wellwith the exact shell-model calculation in a simplecase but differ from the Hartree-Fock results. Thisdifference is due to an improper definition of thecollective coordinate. We have also defined a moreappropriate collective coordinate and calculationswith it are in progress.

( C. Jacquemin and J. C. Parikh )

A Mass Formula Based on the Single ParticlePicture of the Nucleus :

In recent years HF calculations with Skyrmeinteraction have given a very good account of thenuclear ground state energies. It can be shown thatthe many particle wave function in this case belongsto a single one-dimensional representation of a directsum unitary group defined by the single particlestates. The energy of the state can then be expressedin terms of the scalar operators of the group. In thisway we find a seven parameter mass formula. Sincethe structure of the single particle orbits changeswith mass number the parameters would be reaso-nable only for a limited region of the periodic table.We have therefore divided the periodic table intosix different sets and made a least squares fit of theparameters to the empirical binding energies. Wehave thus determined six sets of parameters and atotal of about 1200 nuclear energies have been fitted.A nice fit to the data is obtained with the meansquare deviation ranging from 1.8 (MeV)8 to 7.5(MeV)a.

( J . C. Parikh )

Normality of Term Spectra in Atomic Physics.

It has been shown that the density of statesin a nucleus has a Gaussian form. The generalarguments which lead to this result are based onthe application of the central limit theorem to theproblem. This result has much importance in nuclearphysics because it enables one to use statisticalmethods to study nuclear properties.

The same kind of analysis can be made forlevel density in atoms; one expects that it shouldalso have a Gaussian character. If in fact it turns outto be of this form then one can immediately applythe statistical methods to atomic systems.

L19

In view of this, the term spectra of electronsbelonging to the configurations (3d)5 and (4f)G inatoms are studied. It is found that these are essen-tially normal. Before we make extensive applicationsto atoms, making use of this result, we propose tostudy in greater detai! statistical properties of atomicspectra.

( J . C. Parikh )

Ground-State Occupancies and! Effective Inter-actions in s-d Shell.

Ground state occupancies of nuclei in s-d shellhave been calculated using spectral averagingmethods. Occupancies obtained with ten differenteffective interactions have been compared with thoseobtained from experimental data on s-d shell nucleiwith masses ranging from A = 20 to A = 36. It isfound that different interactions give widely varyingvalues for s1 / a ground state occupancies. A closecorrelation has been found between s 1 / s occupanciesand s1 / 2 single particle energies as renormalised bythe effective interactions for each nucleus. Compa-rison of calculated and experimental occupanciesthus determine an important parameter of the inter-actions, and favours only a particular subset ofinteractions studied. The success of the methodshould stimulate further experimental work, andenable an easy but precise test of the empiricallychosen effective interactions.

(V. Potbhare and S. P. Pandya )

QUADRUPOLE POLARIZABILITIES IN EVEN-EVENNUCLEI WITH A =70-80.

Some recent lifetime measurements indicate anincrease in equilibrium deformation of about 22 percent in going from 70Ge to 7 1 As. The relativeincrement in ground state deformation in going from7aGe to 73As is however found to be only 14 percent. Further, the experimental B(E2) measurementsindicate practically no change of deformation uponthe addition of a proton to S0Kr. Constrained HFBcalculations were recently carried out in the f-p-gspace employing suitable effective interactions. Thecalculations reproduce well qualitatively the empiricaldeformation-systematics in the region A = 70-80.

( S. K. Sharma )

SHELL MODEL SPECTRA OF 9aTc AND 9 3Ru.

The spectra of 9 1Mo, 9 a Tc and 9 3 Ru werecalculated using the empirical interaction matrix

elements for protons and a neutron hole in the gs/a

orbit. The ground state binding energies and theexcitation spectra are in good agreement with experi-ment. (See fig.)

( D. P. Ahalpara and K. H. Bhatt)

PLASMA THEORY

Plasma Physics has come of age ana simplelinear theories depicting short time processes havealready been studied in detail. Any substantial pro-gress can now be made if and only if one studiesnonlinear processes. This is reflected very much inthe choice of problems made by the group. Shockwaves, solitons and nonlinear stabilization processes,nonequilibrium process, turbulence are some of thefew topics in this class of problems. A wide varietyof such problems have been tackled and are beinginvestigated by the group both in the context ofspace as well as laboratory plasmas.

ASTROPHYSICS

Dynamics of Inhomogeneous NonequilibriumMagnetoactive Plasmas.

We have formulated the dynamics of the inho-mogeneous magnetoactive plasma far removed fromthe equilibrium state in the framework of irreversiblestatistical mechanics. It is shown that in general,there are nine energy transfer processes in a non-equilibrium plasma and in studying the radiationemanating from this plasma, one has to considerthree plasma processes. It is also shown that pastconsiderations in nonlinear dynamics are a specialcase of the analysis presented here. The relevanceof the analysis in the light of recent observationsin Solar Radio Astronomy has been demonstrated.In this we have l&id the foundation for a generaltheory of Plasma Turbulence when it is nonequili-brium, inhomogeneous and magnetoactive in nature.

(R. Pratap)

Cylindrically Symmetric Matter Distributionwith a Magnetic Field in Einstein - CartanTheory.

We have extended our earlier studies of solu-tions of Eirstein - Cartan equations to the casewhere a magnetic field co-exists with the matterdistribution. We have obtained an exact solution ofEinstein-Cartan - Maxwell equations representing astatic cylinder of perfect fluid with an axial magneticfield H and a non-zero-spin density K, satisfying the

20

equation of state 9 = y (Pr + Pz ~ H 3 / ^ ) , Y being aconstant. We notice that as a consequence of fieldequations there exists a direct relation between thepressure p, and the spin density K, indicating that anincrease in pressure would enormously increase thespin density.

(A. R. Prasanna )

Maxwell's equations inSpace U4 .

Riemann - Cartan

Starting from the invariant form of Maxwel!equations we have derived the covariant set ofMaxwell equations in an U4 referred to the mostgeneral frames.

(A. R. Prasanna )

Static Cylinder of Perfect Fluid with Non-zeroSpin Density

We have studied the interior field of an infinitestatic cylinder of a perfect fluid having the spins ofthe individual particles aligned along the axis ofsymmetry. We have obtained a solution with anassumed equation of state and expressed the pre-ssure and the density as departures from their valueson the symmetry axis. As in the case of sphericalsymmetry,, the pressure is discontinuous across theboundary of the cylinder.

(A. R. Prasanna )

Static Fluid Spheres in Einstein-Cartan Theory

Following the work of Trautman we have des-cribed briefly the Einstein - Cartan equations withspecial reference to a perfect fluid distribution andthen obtained three solutions adopting Hehl'sapproach and Tolman's technique. We have foundthat a space-time metric similar to the Schwarzchildsolution (interior) will no longer represent a homo-genous fluid sphere in the presence of spin density.At the boundary of the fluid sphere the hydrostaticpressure P is discontinuous.

(A. R. Prasanna )

INTERPLANETARY AND MAGNETOSPHERICPLASMA

Ring Current and Antiloss-cone Drift Instability

The quiet time extraterrestrial ring-current, whichhas a peak at about 7 RE/ has protons of KeVenergies. In these high-(3 (fj being the ratio of

kinetic pressure to magnetic pressure ) plasmas whichare governed by antiloss-cone distribution function,an electromagnetic high frequency drift instabilitycan arise provided the strength of the antiloss-coneexceeds a critical value. The growth rates associatedwith this antiloss-cone drift instability are of theorder of or even greater than the electron cyclotronfrequency.

(B. Buti)

Antiloss-cone Instability in Magnetosphere

Magnetospheric plasma just outside the plasmasphere is characterised by an antiloss-cone (ALC)distribution function. A new high-frequency electro-static instability in these ALC plasmas has beenshown to occur when the strength of the antiloss-cone exceeds a critical value. The growth rate, forelectrons (observed by OGO 3 ) of energy density/-^108 ergs cm-3- can be about 0.5 times the localelectron cyclotron frequency.

(B. Buti)

Side - band Growth in the Whistler Mode andVLF Emissions

The VLF emissions are still a puzzling pheno-mena and no simple theory has been given. Althoughit is believed that the resonant interaction betweena wave packet and the energetic particles is themain mechanism for these emissions, the exacttrajectory computation and the evolution of the dis-tribution function in presence of many waves havenot been done yet. We have for the first time studiednumerically the trajectory of particles in presenceof two whistler mode waves of equal amplitudes. Itis seen that the particles are still trapped as in thecase of a single wave although the trajectory isdistorted and the concept of trapping becomes quiteinvolved. The investigation cf s'ow evolution of thedistribution function has shown side band growthsfor two waves at frequencies slightly higher thanthose obtained in the case of a single wave. Thisindicated that the policies interacting with manywaves in a wave packet may also lead to side bandgrowth which is one of the most important charac-teristics of the triggered VLF emissions.

(V. H. Kulkarni and A. C. Das)

Resonant Interaction of an ElectromagneticTest Wave with Electrons Trapped in anElectrostatic Wave

We have studied the resonances of a whistlermode test wave in presence of a large amplitude

21

electrostatic wave. The whistler is seen to experiencea new series of resonances. These resonances areessentially due to particles trapped inside the para-bolic part of the potential well of electrostatic waves.It is also shown that there exists a new set of'Natural side band resonances.'

(V. H. Kulkami and A. C. Das)

On the Triggering of an Isolated MagneticSubstorm : A Theory

We propose a possible mechanism that cantrigger an isolated magnetic substorm and the con-comitant reconnection of oppositely directed magneticfield lines. Such a theory is motivated by recentexperimental observations supporting the formationof x-type neutral point in the near earth region(15RE -30RE ) during the magnetic substorms. Weconsider a high frequency electromagnetic instabilitydriven by cross current as a source for the onset ofsubtorm expansion phase and the formation of neu-tral point beyond 15RE. Using a kinetic theory, anonlocal dispersion relation is derived and we showthat the instability can be excited for a broad spec-trum of wavelengths. The nature of the perturbedelectric field for different modes is discussed in detail.By including a normal component of tail field, Bz,we find that the instability can be quenched providedBz exceeds a certain threshold value, 0.06 r, fortypical values in the neutral sheet,

( M. Sinha and A. K. Sundaram )

IONOSPHERE

Nonlinear Rayleigh - Taylor Mode

We have made an investigation of the nonlinearevolution of the gravitation-induced Rayleigh-Taylorinstability which may be one of the possible mecha-nisms responsible for equatorial spread-F. In a weaklynonlinear limit, it is found that coherent, nonlinear,almost sinusoidal, stationary solutions of the non-linear equations describing Rayleigh - Taylor modesexist for the phase velocity greater than VL, the ionthermal velocity. It is noted that the phase of thewave changes slighlty indicating that the modesdevelope into slightly distorted shapes rather thanpure sinusoidal forms. The final structure of the modesmay therefore have slightly distorted wave like forms

which have been observed in the equatorial spread-Fregion.

(A. C. Das and R. K. Jain )

Equatorial Sporadic E and Growth-rate ofAssociated Irregularities

It has been shown that the sporadic E confi-guration observed in the ionograms from equatorialstations can suddenly appear or disappear in a timeperiod of one minute or less. Such short decay (orgrowth) times are found to agree with theoreticalestimates of cross-field instability calculations. Thesefindings further support the identification of Es-q tocross-field instabilities. Attempts should be made tostudy the real time evolution of these irregularitiesby backscatter radars or finer time resolved ionosondeobservations.

( R. G. Rastogi, M. R. Deshpande and A. Sen )

Artificial Control of Equatorial Spread F

We have studied the influence of a large ampli-tude electric field oscillating near the upper hybridfrequency on the dispersion characteristics of lowfrequency Rayleigh - Taylor modes and collisionaldrift modes. Since these modes have been*proposedas principal constituents of spread F, we investigatethe conditions for the parametric excitation or controlof these F region irregularities by an external field.We obtain the modified growth rates as well as thethreshold power necessary to carry out such a groundbased 'modification' experiment. The propagationcharacteristics of the pump wave are also brieflydiscussed.

(S. Bujarbarua and A. Sen )

An Interpretation for the Power Spectrum ofSpread F Irregularities.

The k~3 power spectrum of long scalelengthspread F irregularities is interpreted in terms of atwo - step theory. The analysis is carried out usinga mode - mode coupling approach for the two - stepprocess instead of a 'linear' one as used earlier. Thisresults in a better physical understanding of theprocess and shows that it does not take place forcertain combinations such as a drift wave growingon a drift wave.

(P. K. Chaturvedi and P. K. Kaw)

22

Steady StateSpread F

Rayleigh - Taylor Modes in

Some special steady state solutions for the onedimensional set of nonlinear equations describing thoRayleigh - Taylor instability are presented. The rele-vance ot the results is discussed in the context ofequatorial spread F where recently coherently deve-loped wavelike structures have been observed.

( P. K. Chaturvedi)

LABORATORY AND SOLID STATE PLASMAS

Velocity Shear Induced Flute Instabilities inPlasmas

The effect of velocity shear across the magneticfield on the low frequency flute modes is examinedin detail, using the normal mode analysis. It is shownthat some new type of instabilities driven primarilyby the velocity gradient arise and these excited modeseventually attain the convective saturation. The onsetof plasma turbulence due to these instabilities maypossibly be one of the major contributions for ananomalous heating process and enhanced plasmaresistivity.

( M. Sinha and A. K. Sundaram)

Feedback Suppression of Dissipative TrappedParticle Instabilities by Neutral Beam Injection

We investigate the feedback suppression oftrapped particle instabilities of the magnetic type bymodulated neutral beam injection. The neutral beamacts both as a particle source and a momentumsource and it is found that the potentially dangerousdissipative trapped particle modes may be effectivelyquenched by means of a negative feedback at - 90°phase.

(A. Sen and A. K. Sundaram)

Influence of a High Frequency Pump on TrappedParticle Modes

We investigate the influence of a tower hybridpump field on the dispersion characteristics of varioustrapped particle modes and delineate the conditionsfor their excitation or suppression. Our calculationsalso reveal the existence of certain new instabilitiesdriven by pump.

(A. K. Sundaram and A. Sen)

Excitation and Suppression of Kink Modes byCoupling to Ion Acoustic Waves

We have investigated the stability of kink modesin a cylindrical plasma column under the influence ofan oscillating magnetic field applied in the azimuthaldirection. The frequency of the applied field is chosenclose to the ion acoustic frequency. It is found thatcoupling to damped ion acoustic waves induces asmall real frequency to the kink modes which cansignificantly affect their growth rates. We delineateconditions for parametrically suppressing (or excit-ing ) these modified kink modes.

(P. Guzdar, A. Sen and P. K. Kaw)

Modulational Instability in the PresenceLangumir Turbulence

of

Wo investigate the effect of high frequency shortwavelength Langmuir turbulence on parametricallydriven modulational instabilities and find that turbu-lence reduces their threshold for excitation. We alsofind an interesting modification of the modulationalstability of the Langmuir p!asmons due- to the pre-sence of the pump wave.

( P. Guzdar and A. Sen )

Stimulated Raman Scattering in a Plasma withRandom Density Fluctuations

We have carried out a detailed analytical investi-gation of the effect of random density fluctuations onstimulated Raman Scattering (SRS) in a Plasma.Starting from model equations for two coupledmodes, we derive a basic integro-differential equa-tion with coefficients which are random functionsof space and time. Assuming the level of fluctuationsto be small, we solve this equation using methodsfrom wave propagation in a random media. For alow frequency long wavelength background turbu-lence, we find that complete stabilization of SRSis possible, provided the phase velocity of theturbulent waves exceeds the group velocity of theplasma waves. In the quasi-static limit we once againrecover our earlier results.

(P. Guzdar, A. Sen and P. K. Kaw)

23

Particle Transport in a Tokamak

An investigation of the particle transport processin a tokamak has been carried out. The transportarises due to the polarization electric field producedby the trapped particles under the action of thisinduction electric field. It is shown that this polari-zation electric field causes the E X B drift of theplasma in the same direction as the inward wavedrift of the trapped particles.

( R. K. Varma )

Decay Instability of Lower Hybrid Wave in aCold Homogeneous Plasma

We have pointed out the possibility of parametricexcitation of a low frequency wave, propagatingalmost perpendicular to the magnetic field in a coldhomogeneous plasma, by a lower hybrid pump wave.The growth rate and threshold power are calculated.

(S. Bujarbarua and Y. S. Satya )

NONLINEAR WAVES

Modulational Instability of Ion - Acoustic wavesin Collisional Plasma

Nonlinear ion-acoustic waves, which in theabsence of collisions are modulationally stable in thelong wave length limit, become modulationally un-stable due to presence of collisions. These wavesare unstable in a limited wave number range.

( B. Buti )

Effect of Random Inhomogeneities on Non-linear Ion-Acoustic Waves

The envelope characteristics of long wavelengthnonlinear ion-acoustic waves in the presence ofrandom density inhomogeneities are studied. Thesewaves are found to be modulationally stable andhence admit envelope hole solutions. The width ofthe envelope hole is increased due to the increaseddispersion of the plasma.

(A. S. Sharma and B. Buti)

Envelope Solitons and Holes for Sine - Gordonand Nonlinear Klein - Gordon Equations

The nonlinear Schrodinger equations governingthe evolution of the plane wave solutions of theSine-Gordon and the nonlinear Klein-Gordon equa-tions are derived. The former is unstable against

modulational instability and thus evolves into enve-lope solitons. The latter, however., can be unstableor stable depending on the sign of the cubic termand can accordingly admit envelope soliton or holesolutions.

(A. S. Sharma and B. Buti)

Modulational Instability and Envelope Solutionsof Nonlinear Dispersive Wave Equation

The nonlinear Schrodinger equation describingthe evolution of the plane wave solutions of thegeneralized nonlinear dispersive wave equation andof the Boussinesq equation are obtained. The condi-tions for modulational instability and the localizedstationary solutions are derived.

(A. S. Sharma and B. Buti)

SOLITARY AND SHOCK WAVES

Ion Acoustic Solitary Waves in a Two-Electron-Temperature Plasma

Due to the presence of a relatively cold electroncomponent in a plasma, the ion acoustic solitarywave of a given width has a larger amplitude. Whenthe temperature difference between the two electroncomponents is sufficiently terge, the strength ofdispersion is reduced to an extent that a solitarysolution is no longer possible.

( B. N. Goswami and B. Buti)

Nonlinear Drift Dissipative Instability in Colli-sional Plasmas

A modified K-dV equation for the propagationof a weakly nonlinear drift dissipative ion acousticwave in the presence of ion viscosity is derived byusing reductive perturbation method. When viscosityeffects are strong enough, to overcome the destab-ilizing effects due to (he collision this equationallows a stationary shock solution. Numerical inte-gration of the equation reveals that it will permitsolitary solutions if the net stabilizing or destabilizingeffects a-e not too strong. The solitons thus obtainedare found to either grow or decay with time depend-ing on whether the viscous effects are weaker orstronger compared to the collisional effects.

(B. N. Goswami, P. N. Guzdar and B. Buti )

Solitons and Turbulence

There is a growing feeling that the strongplasma turbulence could perhaps be more appro-

24

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priately described in terms of the solitons as thebase rather than in terms of the Fourier componentswhich are strongly interacting. Solitons which arethe nonlinear excitations of the medium are ratherweakly interacting entities like the quasi-particles inmany situations. The turbulence could then be consi-dered as simply the dynamics of these weakly inter-acting solitons with random phase. Various aspectsof this problem are being considered.

( R. K. Varma )PLASMA INSTABILITIES

E. M. Drift Instabilities in High- P Antiloss-cone Plasmas

The stability of electromagnetic drift waves, inhigh- p (p - being the ratio of kinetic pressure tomagnetic pressure ) antiloss-cone plasmas, is investi-gated. These waves with wave propagation transverseto the external magnetic field are found to be un-stable provided the parameter which characterizesthe strength of the anti-loss cone exceeds a criticalvalue. The growth rates associated with this insta-bility (which may be called antiloss-cone driftinstability) are•—' 0.1 Qe and they increase as thestrength of the antiloss-cone increases.

(B. Buti)

Cross Field Current Driven Electrostatic Insta-bility in Plasmas with Generalized DistributionFunction

The generalized distribution function is used toinvestigate the effects of loss-cone and temperatureanisotropy on the cross-field-current driven electro-static instabilities, namely modified two-stream insta-bility, ion-acoustic instability and electron cyclotrondrift-instability. These effects are important onlywhen A = k2 pf / 2 ~ I ( k is the wave numberand pe is the electron gyroradius). It is seen thatnonMaxwellian plasmas with distribution index J$*1 ,can sustain fast growing waves even in the regionsof k-space which are stable for a Maxwelfian plasma.Moreover, when A ~ 1 , the temperature anisotropy isfound to have a destabilizing effect on the modified-two stream instability and on ion acoustic instability.

(B. N. Goswami and B. Buti)

QUANTUM MECHANICS

Deterministic Equations of Motion for Quan-tum Mechanics

are

A deterministic set of model equations of motiongiven as a generalization of the equations of

motion of classical mechanics. The generalizationconsists in introducing an extra coordinate -an angular coordinate with the corresponding metricg. Using the angular coordinate as the "free" variableit is shown that the equations of quantum mechanicsand its generalizations obtained earlier can be derivedfrom this deterministic model and the potentialappears as being a property of the structure of thisspace determinined by the metric component g.

An explanation for the uncertainty relation isoffered in terms of this model and an interpretationfor Planck's constant is also given.

( R. K. Varma )

ATOMIC AND MOLECULAR PROCESSES

Double Chebyshev Expansions for WaveFunctions

Solutions of linear differential equations whichoccur in atomic or nuclear scattering problems maybe obtained in terms of Chebyshev series expansions.This method has previously been discussed by theauthor to obtain both the regular and the irregularsolutions of (i) the radial Coulomb equation, (ii) theradial Coulomb equation modified with long-rangepotential terms and (iii) the relativistic radial Coulombequation. An advantage of this technique is thatwave functions and their derivatives can be represent-ed to a very high accuracy in terms of only a smallnumber of Chebyshev expansion coefficients over thedomain (O,oo) of the independent variable. Also sincethe method enables one to evaluate the irregular solu-tion of the radial Coulomb equation the Green's fun-ction of this equation may be evaluated. This functionhas often proved useful in formulating scatteringproblems but has not proved useful in numericalcalculations because of the difficulty of accuratelycalculating the irregular solution.

The Chebyshev expansion technique has nowbeen extended to obtain expansion coefficients bothin the independent variable and in a parameter whichis essentially the inverse wave number. Thus, for avery wide range of energies (13.6 e V - oo eV ) andfor both attractive and repulsive potentials, solutionsof the equations mentioned above may be expressedin terms of a double Chebyshev expansion. Thismethod would facilitate solving problems such aselectron impact ionization of atoms and ions andelectron impact' excitation of ions.

4

(V. B. Sheorey)

25

Low Energy Electron - Argon Scattering

The scattering potential for electron - rare gasatom scattering may be obtained by extrapolating tozero charge potentials for scattering of electrons bypositive ions isoelectronic with the rare gas atom.The potentials for the scattering of electrons bypositive ions are, in turn, obtained by use of accurateexperimental spectroscopic data for the isoelectronicsequence. In the case of argon spectroscopic datahas only recently become available and work is inprogress for evaluating low-energy elastic scatteringphase shifts for electron-argon scatterings.

(V. B. Sheorey)

LABORATORY PLASMA & ASTROPHYSICS

EXPERIMENTAL PLASMA PHYSICS

The areas of research currently in progress are :

i) Collisional plasma instabilitiesii) Nonlinear wave interactioniii) Plasma-neutral gas interaction in a magnetic

field, and

iv) Electron trapping and nonadiabatic escapein magnetic mirror.

The following is an itemised summary of the activities:

An experimental system for laboratory simula-tion of electrojet instabilities

An experimental system to simulate the colli-sional plasma instabilities in the equatorial eletrojecthas been assembled. The plasma is created by R. F.ionization of Argon gas at 10~3 torr in a stainlesssteel vacuum chamber (30 cm diameter, 60 cmlength). The plasma parameters are Ne = 109 /cm3 ,Te=2 eV, radial electric field 1-3 v/cm. Densityscale length 10-15 cm. The axial magnetic field issuch that ve<i2e and VJ>Q| where ve and vj arethe collision frequencies and il is the gyrofrequency.

The collisional plasma instabilities, generatedby the crossfield current and density gradient arestudied by radially movable Langmuir probes. Afternecessary signal processing, the analogue data isrecorded on an Ampex FR 2000 analogue magnetictape recorder. The data is then digitised and trans-ferred to a digital tape recorder. The digital data canbe further analysed by digital computer. Modificationof the R. F. electrodes to produce an annular gradientfree plasma region is in progress.

(P. I. John and Y. C. Saxena )

Experiment on Streaming Instability

In a plasma maintained in an axial magneticfield and radial electric field and in which ions arecollisional and electrons are magnetized, there wilibe a net azimuthal drift between ions and electronsin the E X B direction, resulting in a crossfield current.When the azimuthal drift velocity of electrons exceedsthe ion acoustic velocity, the plasma becomes un-stable to a micro instability called Streaming orFarley-Bunemann Instability.

The experiments are done in a R. F. ionizedArgon plasma. The plasma is relatively stable at lowmagnetic fields. Above a critical B the plasma isdestabilized to electrostatic waves travelling in theE X B direction as verified by azimuthal cross corre-lation measurements. The instability frequencies areabove the ion gyrofrequency. The phase velocityexceeds the ion acoustic velocity but is bslow theelectron drift velocity. These features agree well witha linear theory of Farley-Bunemann Instability. Thepower spectrum, measured by correlation techniquesshow that the index of potential wave is - 3 to -4 .

(P. I. John and Y. C. Saxena )

Experiments on Crossfield Instability

A plasma in which the conditions Ve<^e-V i £ & i ' E II VN-LB (where v i s the collisionfrequency; £2 the gyrofrequency, E the electric fieldand V N the density gradient) are satisfied, alow frequency (co< i i j ) instability is destabilizedwhen the electric field and density gradient exceeda critical value. An instability satisfying these condi-tions has been observed in the electrojet simulationexperiment. The instability gives rise to electrostaticmodes travelling in the E X B direction. The parallelwavelength is considerably more than the parallelmachine length and is sustained by ion sheaths. Theinstability is stabilized when the end sheaths aremade electron rich. The spectrum of the potentialfluctuation has an index of -5. The development ofthe instability gives rise to crossfield turbulent diffu-sion of particles.

(Y. C. Saxena and P. I. John)

Non-linear Splitting of Ion Rarefaction Waves

Many experiments have been performed onpositive ion acoustic pulses, but relatively few onnegative, rarefaction waves. To contrast their beha-viour we performed an experiment on ion rarefactionwaves. The experiment is done in a quiescent largevolume Argon plasma produced by electron impactionization. The positive pulses applied to a grid

26

form the well-known solitons. The negative pulsesstart out with the same width and height as thepositive pulses. They then broaden and suddenlydevelop a double peak. The characteristic bifurcationappears only at high amplitudes.

The non linear splitting is explained theoreticallyin terms of the coupling of a gaussian pulse to itssecond harmonic. The experimentally observed ampli-tude of second harmonic component agrees reaso-nably well with the values obtained using the modecoupling calculation.

( I . Alexeff, P. I. John and Y. C. Saxena )

A Large Volume Plasma Device

In many plasma physics experiments, a fieldand gardient free quiescent plasma with dimensionsfar larger than wavelegths or particle mean free pathsis desirable. A machine satisfying these conditionsand in which large amplitude waves and strong ionbeams can be launched and studied has been built.

The plasma is produced by low pressure (10~4

torr) Argon by impact ionization by electrons froma large number of spatially distributed hot tungstenfilaments. The usable volume is cylindrical, 30 cmdiameter, 100 cm length. Typical plasma density is10s /cm8 and electron temperature is 2-7 eV.

The apparatus can be operated in the double-plasma mode by a negatively biased grid at the centreplasma, which inhibits electron flow between thetwo sections. Raising the potential of one plasmawith respect to the other, large amplitude waves(10-20% fractional amplitude and dense ion beams(Nb/Np ~ 1) can be launched into the experimentalplasma region. Langmuir probes, located at variouspoints are the diagnostics.

(P. I. John and Y. C. Saxena )

Soliton Damping and Growth in Plasma DensityGradients

In plasmas with Te>Ti a compressional pulseevolves into a solitary ion acoustic wave propagatingwith a velocity greater than the ion acoustic velo-city and width inversely proportional to the ampli-tude. These waves have recently attracted consi-derable theoretical and experimental attention. Asthe soliton properties result from a balance betweennonlinearity and dispersion, an experiment to studysoliton propagation characterstics in plasmas withdensity inhomogeneity has been performed.

The experiments are done in the double plasmamachine, Ne = 107 /cm3 ; Te = 8 eV. Density gradientsare produced either by proper spatial distribution of

electron emitting filaments or by having the plasmadiffused into a cylindrical cavity. The experimentsreveal that solitons damp when they travel intodecreasing density and amplify when they travelalong a positive gradient. The velocity of the solitonbehaves conversely. Results are in agreement withthe theoretically predicted behaviour.

(P. I. John and Y. C. Saxena )

Development of Electromagnetically Accelerat-ed High Density Plasma Source

To perform basic investigations on plasmainteraction with neutral gases in the presence of anexternal transverse magnetic field, a coaxial plasmagun with pulsed gas inlets has been designed andbuilt. A condenser bank made up of 3 kilojouleZEUS capacitor is charged to 20 KV, and fired throughan atmospheric pressure spark gap triggered by a7 KV pulse generated by thyratron circuit. Electro-magnetically operated pulsed gas valves are used toinject variable amounts of gas into the gun. TheJ X B force developed within the gun acceleratesthe plasma and ejects it into the drift tube madeup of pyrex glass. The magnetic field is generatedby 6 coils of water cooled hollow tube magnetspowered by a 60 KW 300 ampere supply.

(S. K. Matoo, P. I. John and Y. C. Saxena )

Electron Confinement and Nonadiabatic Escapefrom a Magnetic Mirror

To study the confinement of electrons and theireventual escape from a magnetic mirror, an experi-ment has been designed and set up. The experimentis done in a glass vessel of 10 cm diameter and150 cm length, pumped to better than 10~8 torr bya locally made mercury diffusion pump. The mirrormagnetic field is created by 12 pairs of water cooledmagnets, displaced suitably to provide a mirror ratioof 2.5. Electrons are injected into the system from anelectron gun, and trapped by lowering the mid-region magnetic field for about 300 nanosecond.Experiments on trapping are in progress.

( Dhiraj Bora, P. I. John and Y. C. Saxena )

A Simple, High-Speed Auto and CrossCorrelator.

A simple correlator for plasma studies was madeusing an LC delay line and a diode multipler. Unusualengineering details are an asymmetric 3 - diodemultipler, and a compensated, distortionless delayline. The high frequency limit is apparently givenby the cut-off of the diodes, while the low frequencylimit is arbitrarily low. The correlator was used

27

successfully to study the Farley - Bunemann insta-bility in a magnetized plasma at frequencies near100 kilohertz.

( I . Alexeff, P. I. John and Y. C. Saxena)

LABORATORY ASTROPHYSICS

We are mainly concentrating, at present, on thephoton - gas interaction studies in the extreme ultra-violet region. Major efforts of this group during thelast year, have been devoted to building up theexperiment on photoelectron spectroscopy of gasesof planetary interest. There has, so far, been aconsiderable progress in the development of variousphases of the experiment.

E U V Light Sources

Both continuum and line sources have beendeveloped in the laboratory. BRV source which isa three electrode vacuum spark source with oneelectrode as the triggering electrode, and uranium asthe anode, has been designed and fabricated. Thethyratron triggering unit is also ready. Work is goingon for making 25 KV, 200 mA power supply. BRVsource would produce very intense continuum in the

spectral range of 200 A to 3500 A.

Other EUV sources like Hinterregger source(both continuum and line), microwave dischargesource (both continuum and line ) and penning dis-charge source (line only) have also been made/procured in the laboratory.

(Vijay Kumar, Satya Prakash and P. N. Pareek)

E U V Monochromators

One half-metre Seya-Namioka type monochro-mator with differential pumping arrangement on boththe entrance and exit sides, has been designed andis being fabricated right now. It would have a beam

o

resolution of 1 A and would cover the spectral

range from 600 A to 2000 A.An asymmetrical type one-meter monochromator

o

with a beam resolution of 0.1 A (spectral range :O a

300 A to 3000 A ) has been purchased from Jobin-Yvon, France. The pumping system and control unitare being fabricated in the laboratory.

(P. N. Pareek, Satya Prakash and Vijay Kumar)

Photoelectron Spectrometer

A high resolution (50 mv at 5 eV) photo-electron spectrometer has been designed and fabri-

cated in the laboratory. The spectrometer is basicallyan electrostatic analyzer. The photoelectrons produc-ed in the photon-gas reactions are allowed to ema-nate from a line source and are received by theanalyzer at an angle of 45° ^ 1.5°. After energeti-cally analyzing the photoelectrons, they are detectedby a channel electron multiplier array (CEMA)operated in the proportional mode.

(Vijay Kumar, Satya Prakash and P. N. Pareek)

Electron Counting and Data Storage System

The electronics has been designed to measuresingle electrons. The preamplifier linear amplifier,analog-to-digital converter and step-voltage generatorhave been made to suit the specific requirements ofthe experiment. The data is stored in the Pertecdigital tape recorder. The interface unit has beendesigned and is being fabricated in the laboratoryalong with other programming circuits.

(Satya Prakash, R. S. Singh and Vijay Kumar)

GEOCOSMOPHYSICS

The main research programs of the group fallunder three distinct disciplinary beak-ups : Lunarand Meteorite Research, Isotope Geology andPhysical and Chemical Oceanography. Lunar sampleshave been studied under two projects with the NASA.Isotope Geology work on Indian rock provinces hasbeen recently undertaken with collaboration from theGSI, Calcutta and other institutions. Oceanographicwork includes active collaboration with ScrippsInstitution of Oceanography, California on samples'ram GEOSECS expeditions in the Atlantic andPacific Oceans.

The major experimental facilities are various low-level radioactivity counting systems, mass spectro-meters for solid and gas samples, optical microscopes,scanning electron microscope, Atomic AbsorptionSpectrophotometer, etc.

Skylab ExperimentTrack measurements in lexan stack detectors

from SKYLAB missions have been completed. Theabundances of Ca, Ti and Cr relative to Fe groupnuclei are 0.25+0.12; 0.21+0.12 and 0.26+0.12,respectively. The fluence spectrum of Fe group nucleii9 found to be flat. We believe that the source ofthese low energy particles near the top of the earthis interplanetary cosmic rays based on similaritiesbetween our observations and those reported forinterplanetary space.

( U. B. Jayanthi and S. K. Mattoo )

28

; <"•- ) sasss?

Set of eicfht short back-fire antenna assembly for 360 MHz beaconfrom ATS-6 received at Ootacamund.

,. y\;

Yagi antenna array at 35 MHz.

101-76POLARIMETER RECORO AT 4 0 MHz

LAYERSUNRISE AHMEDABAD

wwvvwfcommencemeni of Stoim WltrNiGHT

v ^ ^

polarimeter records of ATS-6 beacon transmission at Ahmedabad.

Spatial structure during solsticeperiod revealing 3° latitudinaldisplacement of the ledge intothe winter hemisphere thusgiving a direct evidence forthe presence of thecross-equatorial wind.

JAN 18, 74

LONG. 68* EL.T 1250X 20 %

10°

GEOG. LATITUDE±20°

OCT.7.1972. LONG 60°E Z

+ 10GEOG. LATITUDE

Spatial structureof the ionisationledge showing symmetryin the latitudinal extent on thetwo sides of the magneticequator during equinox period.

Large volume quiescent plasma machine for non-linear waveexperiments.

Hi&h density electromagnetically accelerated plasma source forplasma-neutral gas interaction experiment.

Solar Flare Records in Lunar Rocks

Lunar rocks exposed to solar flares for differentlengths of time and with known orientation on themoon and well-preserved surfaces have been ana-lysed for solar proton induced AI-26, heavy nucleitracks and microcraters. The calculated productionrate using contemporary intensity and energy spec-trum agrees with observed results within experimentalerrors indicating very little variation of solar flareproton intensity over two half-lives of AI-26.

( N. Bhandari, S. K. Bhattacharya and J. T. Padia )

Dhajala Meteorite Shower of 28 January, 1976

The Dhajala meteorite shower of 28 January,1976 has been extensively documented. Over ahundred eye witnesses were interviewed to estimatethe meteorite trajectory in the atmosphere. Recoveryoperations were conducted resulting in a valuablecollection of about 45 kgs of the meteorite. Variousparameters of the fall systematics are now collectedin order to able to determine the primary orbitalelements.

( N. Bhandari, A. S. Bhatnagar, D. Lai and J. R.Trivedi)

Laboratory Analysis on the Freshly FallenMeteorite, Dhajala

This meteorite is one of the very rare caseswherein it was recovered within 48 hours of its falloffering a unique opportunity to detect extremelyshort-lived, cosmic ray produced nuclides (e.g.,Mn-52 of 5.5 day half-life). This activity has nowbeen definitively measured along with other nuclidesof interest, like AI-26, Mn-53, Co-60, Be-10. Inaddition, particle tracks, elemental abundances, expo-sure ages have been measured using a variety ofsophisticated techniques. Such an intensive charac-terization of a meteorite in a single laboratory isvery unusual.

(N . Bhandari, K. Gopalan, S. Krishnaswami, D. Lai,M. N. Rao and B. L. K. Somayajulu )

Modulation of Galactic Cosmic Rays in theInterplanetary Space

Using meteorites and lunar samples as probesfor spatial distribution of cosmic rays, it has beenconcluded that the modulation effects of the sunare very small resulting in less than 7% per A.U.gradient of cosmic ray protons (^100 MeV). Thisresult based on AI-26 measurements is valid for the

last million years and is consistent with present daymeasurements by Pioneer space craft.

( N. Bhandari and S. K. Bhattacharya )

Solar Flare Produced Kr andMaterials

Xe in Lunar

In confirmation of our earlier work, we havenow obtained unambiguous evidence for solarcosmic ray effects in rare gas systematics, particu-larly in Xe and Kr. The solar proton produced Krand Xe isotopes have been identified, a"d basedon the excess of such nuclides, solar cosmic rayexposure ages have been calculated using appro-priate production rates. These exposure ages, togetherwith the other conventional ages, will help in eluci-dating the radiation history of lunar samples.

( K. Gopalan and M. N. Rao)

Implications of Solar and Galactic Cosmic RayEffects to the Origin of Meteorites and LunarRegolith

While the gross features of the irradiation receiv-ed by lunar material are now well understood interms of episodic 'sedimentation' with micrometeoritegardening restricted to the top few centimeters, adetailed comparison of grain sizes, track densitiesand exposure ages seems to underscore a verycomplex interplay of various effects. We have evi-dence that the meteorites have received a muchshorter episode of irradiation compared to lunarsamples suggesting that the former have been storedin shielded locations shortly after their primordialirradiation by solar and galactic cosmic rays.

( D. Lai and M. N. Rao)

Developments in Low-Level Radiation DetectorsA non-destructive counting system for measure-

ment of very low levels of gamma radiation hasbeen set up. The (geometry x efficiency) factorrequired for estimating the cosmogenic radioactivityis deduced from the intrinsic K-40 abundance. Alarge number of fragments of the Dhajala meteoritehas been assayed using this system.

A small volume proportional counter for thedetermination of C-14, H-3, Ar-37, Ar-39 in meteo-rites has been designed and fabricated, using aNal(TI) well type scintillator as a guard counter.(N . Bhandari, K. Gopalan and B. K. Srivastava)

Chronology of the Precambrian of Gujarat

Following the establishment of a geochronologylaboratory at the end of last year, igneous rocks

29

outcropping at different locales in Gujarat and adja-cent areas are being dated now to determine theirchrono-stratigraphic relationships. The work is inprogress.

( K. Gopalan, P. P. Patel and J. R. Trivedi)

Investigations of Gram Quantities of. Atlanticand Pacific Surface Particulates

Particulates collected from large volumes(•£, 10,000 litres) of Atlantic and Pacific surfacewaters have been analysed for carbonate, opal,quartz and several natural and man-maderadioisotopes.

The concentrations of particles range between(10-600) microgram per litre, the latitudinal distri-bution exhibits a north-south symmetry with higherconcentrations in the (30° -60°) belt. Based onthe particulate data for CaCOg and opal, we haveestimated their production and in-situ integrateddissolution rates, for a few regions.

The concentration of radioisotopes having diffe-rent source functions, e.g., C-14, Pu-239, Th isotopesand Pb-210 have been measured in the particulates.The relative enrichment factors for these nuclides inparticles vary as Th=sPu]>Pb^>Ra. The atmosphericbomb fallout pattern is discernible in the surfaceparticulates; the Pu-239 concentration increasedwith latitude in both the hemispheres; however, thevalues are about a factor of two lower in thesouthern hemisphere. Based on the distributionpattern of these isotopes and their source functionsit has become possible to delineate the major processwhich controls their concentration in surface waters.(S. Krishnaswami, D. Lai and B. L K. Somayajulu )

Large Volume In-situ Filtration of Deep PacificWaters.-Mineralogical and Radioisotope Studies

The concentrations of CaC03 and radioisotopes,Th-234, Th-230, Pu-239, Ra-226 and Pb-210 weremeasured in particles of ̂ 1 .2 f̂ collected from about4000 1 of Pacific waters at depths 700-5500 m.The results of these measurements have providedinsight into certain aspects of particle dynamicsrelevant to modification of trace element composi-tion of sea water due to particle transport. The de-duced values of rate constant for the adsorption ofthe chemically active element Th on to particlesand of the mean settling rates of oceanic particles(>1.2|J0 ) are presented.

(S. Krishnaswami, D. Lai, B. L. K. Somayajulu,R. F. Weiss and H. Craig )

Silicon-32 Specific Activities in Coastal Watersof the World Oceans

Fairly extensive measurements of silicon-32specific activities in siliceous sponges collected fromthe coastal waters of the world oceans are presented.The measured specific activities of silicon-32 insponges, lie in the range of (4-80) dpm 3 sSi (kgSiC^)"1 and are found to be inversely correlatedwith the concentrations of dissolved silicon in coastalwaters from where the sponges were collected.

The data show that in coastal regions, there isa mixing of different water masses having differentSi-32 specific activities; it is the mixing betweenthe various types of water which determines theSi-32 specific activity in sponges. Hence Si-32 datain sponges should be useful for determining thebudget of silicon in the coastal regions.

( D. Lai, V. N. Nijampurkar, B. L. K. Somayajulu,M. Koide, and E. D. Goldberg )

Particulate Transport of Radionuclides C-14and Fe-55 to Deep Waters in the Pacific Ocean

Samples of particulate materials from the Pacificocean and the Santa Barbara basin were collectedusing the sponge technique and analysed for theirC-14 and Fe-55 concentraton. Based on the depthdistribution of these nuclides in sea water, theirsettling velocities were estimated. The rate of verticaldownward movement of Fe-55 was found to beconsiderably lower than that for C-14 indicating thatFe-55 attaches itself to small particles, compared toC-14. Settling rates for C-14 and Fe-55 were esti-mated to be (1.5-2.0) and (0.4-0.5) meters day"1

respectively.( 0. Lai and B. L. K. Somayajulu )

Authigenic Transition Elements in PacificPelagic Clays

The concentrations of Sc, Ti, Fe, Mn, Co, Ni,Cu, La, Th and U have been measured in severalPacific pelagic clays having widely different accumu-lation rates, 0.4-9.0 mm/103y. The authigenic frac-tions and deposition rates of these elements havebeen estimated from the measured concentrationsusing various models. The results show that inPacific clays about 90% Mn, 80% Co and Ni and50% Cu are authigenic whereas the major fraction(5? 90%) of Sc, Ti, Fe, La, Th and U are of detritalorigin.

Anticorrelation between the clay accumulationrates and the concentrations of Mn, Co, Ni and Cuis observed. This suggestes a uniform authigenic

30

deposition of these elements superimposed on vary-ing amounts of detrital materials. The concentrationsof Sc, Ti and Th are almost independent of sedi-mentation rates, indicating that their authigenicdeposition is small compared to their detritalcontribution.

Comparison of the authigenic deposition andriver input rates shows that Mn, Co and Ni areaccumulating in excess of their supply by factors of2-10, whereas the converse is true for Cu and U.Additional sources to account for the budgetorydiscrepancies of Mn, Co and Ni are discussed, withparticular reference to in-situ leaching of detritalphases transported to the oceans via rivers.

(S. Krishnaswami )

The Simultaneous Determination of Th, Pu, RaIsotopes Pb-210, Fe-55, Si-32 and C-14 in MarineSuspended Phases

An efficient and systematic chemical procedurefor the simultaneous measurement of the aboveisotopes in the same sample has been developed.This method has been applied successfully for themeasurement of various isotopes in oceanic panicu-late samples collected from several tons of sea water.

(S. Krishnaswami and M. M. Sarin )

ARCHAEOLOGY

Palaeoclimatology

A programme to study the palaeoclimate ofN-W India, in collaboration with Deccan College,Poona and the G.S.I, has been initiated with multi-disciplinary approaches using geochemical, radio-metric, geomorphic, mineralogical, palynological andarchaeological techniques. A few samples of quartzgrains, miliolite etc. have been studied using SEMand encouraging results supporting aeolian transportin Saurashtra region have been obtained. Extensivesampling of the region has also been initiated.

( D. P. Agrawal, R. K. Pant and B. Roy)

Paleotechnolocjy

Metallurgical studies of ancient metal artifactsand ores were undertaken to establish the techniquesinvolved in their manufacture and to locate the minesexploited for the purpose. A set of Chalcolithicsamples have been analysed for the presence ofcharacteristic trace elements using emission spectro-scopy and atomic absorption spectrophotometry.1 4C dating of suitable samples from certain siteslike Ambaji have pushed back the date of these

known mining areas to a few centuries before theChristian era.(D. P. Agrawal, S. Kusumgarand R. V. Krishnamurthy)

Studies on prehistoric lithic and ceramic arti-facts were carried out to reconstruct the techniquesthat had gone into their fabrication.

( R. K. Pant)Dating Area

As a national facility, the 1 4 C lab in PRLcontinues to provide dates on archaeological, geo-logical and geophysical samples. About seventy fivesamples were dated during the period March 1975to April 1976. In addition to dating samples, the1 *C lab is also undertaking the following programmes.

Separation of various fractions of charcoal andtheir independent dating to study the extent of 1 4 Cfractionation and contamination in different fractions.

Dating of various fractions of soils with a viewto study the mobility of organic components ofsoils, mechanism of soil formation etc. A set of soilsamples from Chotila in Gujarat has been analysed.( D. P. Agrawal, S. Kusumgar, R. V. Krishnamurthy

and R. K. Pant)HYDROLOGY

Water Potential of Sabarmati Basin

In hydrology, the work has been carried out onSabarmati basin for studying the groundwater aqui-fers and their inter-relationship with the surface waterresources of the region jointly in collaboration withthe Directorate of Ground Water, Gujarat and financialsupport from the Government of Gujarat.

As part of this project several investigationsbased on conventional and nuclear methods havebeen initiated in the basin. In pursuance of theseprogrammes extensive field work has been donewhich is briefly summarized below.

More than 100 stations have been establishedin the Project area for periodical monitoring of waterlevels and major ion chemistry of surface and ground-water resources. Three sets of data (Pre-monsoon,June 1975; post-monsoon, Nov. 1975; and pre-summer, April 1976) have been collected andanalysed. Based on the major ion chemistry of surfaceand ground-water in the Sabarmati basin we havebeen able to identify three major geochemical watertypes in the region.

( M. V. Shah, S. K. Gupta, P. S. Datta )

About 18 stations have been established forenvironmental tritium in the river water in the Sabar-mati basin and analysis of pre and post-monsoon

31

samples completed. In addition, monthly samples ofprecipitation for Ahmedabad during the monsoon of1975 have also been analysed. The absence of bombtritium in shallow groundwater (upto 20 metersdepth ) indicate that it takes more than 10-15 yearsfor the rain to percolate downwards through theunsaturated zone.

As the atmospheric tritium levels have gonedown significantly a new tritium enrichment systemis under development.

(S. K. Gupta and P. S. Datta )

Uranium isotopic analysis of forty samples from15 stations have been completed. These data togetherwith environmental tritium and major ion chemistryare being interpreted to determine the quantity ofground water inflow to the Sabarmati river flow.These data will be used to identify the rechargeareas of confined aquifers.

(S. K. Gupta, D. V. Borole, S. Krishnaswamy,P. S. Datta)

Artificial tritium has been injected at 25 stationsin the project area to tag moisture layers at 70 cmdepth. The movement of the tritium tagged moisturelayer will be followed first in June 1976, October1976 and June 1977. The equipment for artificialtritium analysis has been acquired and installed.

( P. S. Datta and S. K. Gupta )

Static water levels of 15 selected tube wells inAhmedabad city are being continuously monitored.These measurements have shown the interferencepatterns of the tube wells and drastic changes instatic water levels during summer.

(A. H. Patel and S. R. Shah )

A preliminary survey of the coastal areas ofJunagadh and Jamnagar area has been undertakento study the problem of sea water intrusion.

(S. R. Shah, A. H. Patel and M. V. Shah )

32

Facilities

LIBRARY

The PRL Library subscribes to 285 scientific and technical journals.Out of these, 11 important journals were obtained by air-mail. About50 periodicals were received gratis.

848 books have been added to the Library during this year. Thetotal stock of books and bound volumes of periodicals at present is over15,700. Rs. 3,34,234.07 were paid for the purchase of books and towardssubscription of the journals. Rs. 37,858.20 were spent on printing andpublication of scientific papers.

Current Awareness Services in the following fields were continued :a) Aeronomy.b) Archaeology and Hydrology.c) Astronomy.

The following bibliographies were compiled :a) Infrared Physics.b) Nuclear Fission.

Compilations :a) Monthly computerised lists of 'New Accessions to the PRL

Library.' From January, 1976 we have started to add a Key-word Index.

b) Monthly lists of Reprints & Reports received in the Library.c) Catalogue of Reports Vol. 1, No. 2 with Report No. Index Si-

Keyword Index.d) Catalogue of PRL Publications upto March, 1976 with Author

Index and Chronological Index.

Preprints of 12 scientific papers which were accepted for publica-tion were printed.

Six issues of the PRL Newsletter were prepared.

An entire floor was added to the Library. The older back volumesof journals, reprints and data were shifted to the top floor.

COMPUTER CENTRE

The configuration of the computer system is further upgraded byaddition of a drum plotter, a paper tape reader and two teletypeterminals. The present main storage of 256K bytes is also expected tobe upgraded to 384K bytes by addition of 128K bytes in the nextcouple of months. Both plotter and paper tape reader have already goneinto operation. The centre is also generating operative system with multi-programming option to use our powerful peripherals more effectively.A plotter software is being developed under the programming system(PS) and Disk operative system (DOS). Various programs in NumericalAnalysis, Statistics and Nuclear Physics have been developed and keptin the special library meant for them. These libraries grow continuously.

The Computer Centre works 18 hours per day and the usage interms of processing time during the year was 3700 Hrs. Centre hadengaged itself in running various courses in educating its users.

Staff members participated in the following training courses andproject involvement:

(1) Post M.Sc. Diploma of Gujarat University.(2) Programming Course by PRL.(3) Programming Course by Gujarat University.

33

(4) Diploma in computer science by Sardar PatelUniversity.

(5) A course on 44 PS & D 9 S Assembler languagefor the project cell officers of Dept. of Electronics.

(6) Programming courses for the Deputy Engineersby Staff Training College of Government ofGujarat.

(7) Course Organised by Ahmedabad Chapter ofComputer Society of India.

(8) Analysis of the data collected by SITE project.

TECHNIQUES LABORATORYThe service-cum-development programme of

optical thin films and the facilities of glass blowingand liquid nitrogen were grouped together in thetechniques laboratory after its reorganization inJanuary, 1975.

During the year 1975-76, considerable progresshas been made in the thin film project. Test inter-ference filters with a maximum of 19 layers andthe half-width of the pass-band of less than 50 A°have been prepared. Here, it may be recalled thatthe film on a glass substrate should be uniformto within less than 10 Ac over xhe are? of thefilter to achieve the above half-width in the visibleregion of the spectrum. The substrates are rotatedin a planetary fashion during the film depositionsfor getting highly uniform films.

A new parting agent 'Victawet' has been triedfor making unbacked metallic filters of Al and Infor the vacuum ultraviolet region. The work is inprogress.

Various jobs involving multilayer high reflectioncoatings, antireflection coatings and metallizationshave been carried out.

A quartz crystal film thickness monitor hasbeen added to the thin film facility.

A general purpose oil-vapour-free (ion-pumped)vacuum system is being fabricated. The work is nearcompletion.

In the glass workshop about 400 jobs ofdifferent types have been executed. The jobs includedthe fabrication of various distillation units, diffusionpumps, dewar flasks, vacuum gauges, glass to metalseals, quartz-work etc. A spot-welding machine hasbeen added to the glass facility.

The liquid nitrogen facility has supplied morethan 7000 litres of liquid nitrogen to various PRLprojects and outside parties. The storage capacityof liquid nitrogen is being increased by 200 litres.A 7.5 TR replacement compressor has been procuredfor the chilled water unit.

WORKSHOP

Workshop undertook a large variety of jobsranging from microscope parts to a big antennasystem for different scientific experiments of theLaboratory. Currently workshop works in two shiftsand carpentry in one general shift.

Delta antenna of 500 ft x 200 ft size with 110ft high mast for the new lonosonde Recorder wasmade in the workshop. Errection of 16 Yagi antennaarray was completed near Radio Astronomy Hut inSAC campus. Six Yagi antennae revolving at 60 RPMconstant speed were designed and fabricated forATS-6 satellite data collection. A very big job of16 elements short back fire antenna of 12.5 metrex 12.5 metre size for SOLRAD satellite tracking wasdesigned in the Workshop, fabrication of which wasstarted from 1st March, 1976.

Precision jobs like quadrupole Mass Spectro-meter, photo-electron spectrometer, Bennote Tube,Moon rock cutting machine with variable speeddrive and micrometer feed arrangement, were alsoundertaken by the workshop. Vacuum systems formicrometer. Field-ion microscope and coating unitswere successfully fabricated from stainless steelmaterials. Feed-throughs, connectors, coils, vacuumconnections for Laboratory Plasma Experiments werealso made in the Workshop.

Rocket pay-load for Infra-Red Astronomy andAeronomy Experiments, Scanning mirror system andcamera mounting stands for rocket flights observa-tions were fabricated in the Workshop. Many morejobs, small and big, were undertaken for scientificexperiments, technical services and other require-ments of the Laboratory.

RSMD/SAC Tradesmen were working in thePRL Workshop under the guidance of our workshopengineers till end of December 1975.

New building for a sheet-metal and weldingshop providing 1200 sq. ft. area was occupied. Newworkshop equipments like Hydraulic Surface Grinder,HI-CUT centre Lathe, Tool Room Lathe, HydraulicHack-saw machine. Hand shearing machine andBand-saw blade welding machine were added tothe workshop facility.

Mr. N. M. Patel, Engineer SD attended fourweeks Executive development program for "Productiontion Management" organised by National Instituteof Training for Industrial Engineers (NITIE) atBombay.

Two shift supervisors and five tradesmen weresent for "Supervisor's Development Programme" and"Worker's development Programme" respectivelyorganised by the Ahmedabad Productivity Council.

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ELECTRONICS LABORATORY

The Electronics Laboratory made four differenttypes of sealer units, ihree high voltage supplies,three electrical motor speed control units, delay-lineand A. C. Amplifier for GEO : CP and ARC : HDGroups. Different types of small electronics unitswere also built up e.g.. Mains Supply Stabiliser,Telephone pick-up Amplifier and Automatic lightcontrol units, besides the maintenance and wiringjobs.

In addition to this. Electronics Laboratory hastried out to run Mains (220 Va.c. 50 Hz) electricalclock by crystal controlled clock (5 volts output).

With the help of a specially fabricated metaldetector we succeeded in finding out the exactlocation of the steel-sheet spools buried in Sabar-mati-bed near Rly. Bridge, weighing 12 tons each.This was done on request from Chief Engineer,Western Railways. The number of spools were five.

Several different types of electronics equipmentsof various research groups were repaired.

This year the printed circuit board facility hascompleted jobs of P. C. Boards of 100 sq.ft.,weighing about 50 kilograms approximately. In addi-tion to this it also does the job of electroplatingwith Au, Ag, Cr, Ni etc.

To make it more useful, the electronics labora-tory is going to add a Vacuum Type Exposure-frameof medium size and print through hole card processin the printed circuit board facility in near future.

The Electronics laboratory continued to be acentral facility for the maintenance of the electronicsequipment. It also includes the facility of printedcircuit boards, electroplating, pulse height analyserand fabrication of equipment needed by differentgroups in the laboratory.

A small project was given to each new researchscholar. It was completed in a month. The coursein electronics was also conducted for the newresearch scholars.

PHOTOGRAPHY-DOCUMENTATION

During the year under review, the DraftingSection has prepared about 1400 tracings/diagramsincluding maps and PCB circuit drawings, 1950Ammonia Prints and 750 photostencils. In addition,the section has attended to about 600 alterations/additions etc. and has written posters with about1200 lines.

The photography section has attended to variousassignments of the field photography or photographyin connection with functions/gatherings almost everymonth. Furthermore the photography section hasdone copying of 3250 diagrams/drawings, has madea total of 2150 slides and 7350 (enlargement) prints.The Xerography section has turned out about 8400copies since July 1975. The projection jobs that wehave attended to totals to about 210 hours.

ENGINEERING SERVICES(Building Activities)

During the year. Department of space sanc-tioned the construction of Workshop shed for sheetmetal works.

Progress of work is as follows :

a) Workshop shed building has been completedand occupied.

b) Dining Hall for research scholars, attached tothe Guest House, is nearing completion.

c) Foundation work for solrad antenna towers hasbeen completed.

d) . Entire work of additional five floors and libraryfloor is completed, including all building servicessuch as elevators, airconditioning plant andfurniture. The entire nine storied building isoccupied fully. The building is an added attrac-tion of the University Campus area.

e) The possession of 26 acres of land at Thaltej,which was under acquistion has now beentaken for the expansion of research activities.Intitial land development will be started soon.

35

LIST OF PAPERS PUBLISHED DURING1975-76

I. SOLAR AND PLANETARY PHYSICS

1. Ananthakrishnan S., Bhandari S. M. and PrameshRao A.; "Occupation of radio source PKS2025-15 by comet Kohoutek (1973 f), Astro-phys. Space Sci. 37, 275 (1975).

2. Bhonsle R. V. and Alurkar S. K.; "ATS-6 satel-lite signal as calibration source for radio polari -meter" (in press).

3. Bhonsle R. V., Alurkar S. K. and Sawant H. S.;"Effects of ground reflection on the polarizationof radio beacon transmission from ATS-6satellite" ( in press ).

4. Burrows K. and Sastry T. S. G.; "Rocket mea-surement of current distribution in normal andintense equatorial electrojet," J. Atmos. Terr.Phys. 38, 307-311 (1976).

5. Chandra H. and Rastogi R. G.; "Scintillations ofsatellite signals near magnetic equator," Proc.Symposium "Beacon Satellite Investigations ofthe Ionosphere Structure and ATS-F Data,"Moscow, November 1974, 1, 218 (1975).

6. Chowdhuri B. and Saxena Y. C; "Interactionof high muons in association with. EAS, withrock and lead," Pramana Vol. 5, 162-173(1975).

7. Degaonkar S. S.; "Are we alone in theUniverse?," an article published in VedhshalaSouvenir, Udaipur, 1975.

8. Desai J. N. and Vaidya D. B.; "Particle sizeanalysis by forward scattering", J. Coll. & Inst.Sci. 51, 527 (1975).

9. Desai J. N. and Rajaraman T. N.; "Pressurescanned Fabrey-Perot spectrometer for the nightairglow studies," Ind. J. Radio & Spa. Phys.5, (1976).

10. Desai J. N., Narayanan M. S. and Bhavsar P.D.; "Effect of wind finite exposure in photo-graphic determination of effective radius ofluminescent vapour clouds released in upperatmosphere," Ind. J. Radio & Spa. Phys. 4,89 (1975).

11. Deshpande M. R. and Rastogi R. G.; "Preliminaryresults of Faraday rotation measurements usinga geostationary satellite at Ahmedabad," Proc.Symposium on "Beacon Satellite Investigationsof the Ionosphere Structure and ATS-F Data,"Moscow, November 1974, 1, 221-226 (1975).

12. Iyer K. N. and Rastogi R. G.; "Vertical driftcalculations from upward moving ionosphericirregularities (kinks) over the magnetic equator,"Ind. J. Radio & Spa. Phys., 4, 6-9 (1975).

13. Jain A. K., Jayanthi U. B., Kasturirangan K.,and Rao U. R.; "Evidence for short term changesin the intesity and spectrum of hard X-rays forCyg X-4" submitted to Astrophys. Space Sci.

14. Kane R. P.; "Semidiurnal component of cosmicray intensity," J. Geophys. Res. 80, 470 (1975).

15. Kane R. P.; "A study of days showing non-field-aligned diffusion vectors of cosmic raydiurnal anisotropy," J. Geophys. Res. 80, 3509(1975).

16 Kane R. P.; "Equatorial electrojet and inter-planetary plasma parameters," Ind. J. Radio& Spa. Phys. 4, 132 (1975).

17. Kane R. P.; "Relation between solar magneticsector structure and geomagnetic Dst," Proc.Ind. Acad. Sci. 81 A, 233 (1975).

18. Kane R. P.; "Day to day variability of ionos-pheric electron content at mid-latitudes," J.Geophys. Res. 80, 3091 (1975).

19. Kasturirangan K., Rao U. R. and Jain A. K.;"Soft-x-ray astronomy payload for use withsatellites," Ind. J. Radio & Spa. Phys. 4,144-45(1975).

20. Kasturirangan K., Rao U. R., Sharma D. P.,Rastogi R. G., and Chakravarty S. C; "Ionos-pheric effects of transient celestial X-ray andgamma ray events," Ind. J. Radio & Spa. Phys.4, 203-205 (1975)

21. Kulkarni P. V.; "6300 A night Airglow and thegeomagnetic control of the equatorial anomaly,"Proc. of Ind. Acad. Sci. A, 82, 46-54 (1975).

22. Kishnamurthy B. V., Raghava Reddi C, Subba-rao K. S. V., Raghavarao R. and Sharma P.;"Some new observations on equatorial spread-F using phase-path technique," J. Geophys.Res. (1976).

23. Majumdar N. H. and Kulkarni P. V.; "A newmethod for estimation of the neutral tempe-rature in the upper atmosphere by night airglowmeasurements", Ind. J. Radio & Spa. Phys. 4,228-230 (1975).

24 Mattoo S. K,, Bhonsle R. V. and Alurkar S. K.;"Polarization characteristics of a group ofspectral type III solar radio bursts at 25 MHzrecorded on 14 July, 1969," Indian J. Radio& Spa. Phys. 4, 116-119 (1975).

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25. Pradhan S. N. and Shirke J. S.; "D-region atlow latitudes using partial reflection technique,"Ind. J. Radio & Spa. Phys. 1 (1976).

26 Rao U. R., Kasturirangan K., Sharma D. P.,Jain A. K. and Jayanthi U. B.; "Balloon obser-vations of X-rays from celestial sources," Ind.J. Radio Spa. Phys. 4, 199-202 (1975).

27. Rao U. R., Kasturirangan K., Sharma D. P., JainA. K. and Jayanthi U. B.; "Balloon observa-tions of fast intensity fluctuations and flare-like enhancements of X-ray emission from CygX - 1 " (To appear in Astrophys. Space Sci.)

28. Rao V. R. and Kulkarni P. V.; "Night Airglowobservations at the magnetic equator," Ind. J.Radio & Spa. Phys. 2, 269-274 (1973). (appe-ared in 1975 issue).

29. Rao V. R. and Kulkarni P. V.; "Ionosphericphenomena related to 6300A airglcw emission,"Ind. J. Radio Spa. Phys. 4, 157-164 (1975).

30. Rastogi R. G.; "On the criterion of geomagneticfield at the time of disappearance of equatorialEs-q layer," Ind. J. Radio & Spa. Phys., 4,1-5 (1975).

31. Rastogi R. G.; "Westward ionospheric currentsover the dip equator during geomagnetic dis-turbances," Geophys. Res. Letters, 2(4), 142-145 (1975).

32. Rastogi R. G.; "Ionospheric VHF scattering nearthe magnetic equator during partial counterelectrojet," J. Atmos. Terr. Phys., 37, 1609-1614 (1975).

33. Rastogi R. G.; "Geomagnetic storms and elec-trojet currents," Physics News, 6(2), 65-66(1975).

34. Rastogi R. G. and Patel V. L; "Effect of inter-planetary magnetic field on ionosphere over themagnetic equator," Proc. Ind. Acad. Sci., 82A,121-141 (1975).

35. Rastogi R. G., Deshpande M. R. and Sastri N. S.;"Solar flare effect in equatorial counter electrojetcurrents," Nature, 258 (5532), 218-219 (1975).

36. Rastogi R. G., Iyer K. N. and Bhattacharyya J.C; "Total electron content of the ionosphereover the magnetic equator," Current Science,44 (15), 531-533 (1975).

37. Rastogi R. G., Sharma R. P., Iyer K. N. andShodhan V.; "Contours of total electron con-tent (NT) derived from faraday rotation ofbeacon satellite signal at Ahmedabad," Proc.Symposium on "Beacon Satellite Investigationsof the Ionosphere Structure and ATS-F Data,"Moscow, November 1974, 1, 133-136 (1975).

38. Rastogi R. G., Bhattacharyya J. C. and IyerK. N.; "Ionospheric total electron content overthe magnetic equator," Proc. Symposium on"Beacon Satellite Investigations of the Ionos-phere Structure and ATS-F Data," Moscow,November 1974, 1, 129-132 (1975).

39. Rastogi R. G.; "Equatorial F-region electric fieldchanges associated with geomagnetic stormsudden commencement," J. Geophys. Res., 81,687 (1976).

40. Rastogi R. G., Deshpande M. R. and Sen A.;"Equatorial sporadic E and growth rate ofassociated irregularities," Geophys. Letters, 2,496 (1975).

41. Rastogi R. G.; "VHF back scattering fromionospheric E region irregularities near themagnetic equator," Ann. Geophys., 1975 (inpress).

42. Satya Prakash, Gupta S. P., Sinha H. S. S.and Rao T. R.; "lonisation irregularities in theH region during counter electrojet (To appearin Space Research 1976).

43. Satya Prakash and Muralikrishna P.; 'The natureof electric field in E-region close to morningand evening reversals (sent for publication inGeophys. Res. Letters).

44. Shirke J. S. and Degaonkar S. S.; 'The diur.valbehaviour of yearly and six monthly compo-nents in NmF2 at low latitudes," Ann. Geophys.No. 1 (1976).

45. Shirke J. S. and Pradhan S. N.; ''Limitations oflongitudinal approximation to the generalisedmagnetoionic formula," Indian J. Radio & Spa.Phys. (1976).

46. Shirke J. S.; ''Space Research in India usingrockets," Physics News 6, 48 (1975).

47. Shirke J. S. and Degaonkar S. S.; "Low latitudefeatures of annual and semi-annual periodicitiesin NmF2 in American and Indian zones (sub-mitted to J. Atmos. Terr. Phys. 1976).

48. Swarup G. and Bhandari S. M.; ''Correlation ofScintillations visibility with flux density andangular extent of extragalactic radio sources,"Astrophys. Lett. 17, 31 (1976).

II. THEORETICAL PHYSICS

Nuclear Theory

1. Ahalpara D. P. and Bhatt K. H.; "The deforma-tion producing tendency of (d 3 / 3 - f 7 / 2 ) empiri-cal effective interaction," PRAMANA 6, 59(1976).

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2. Ahalpara D. P. and Bhatt K. H.; "Shell Mode!Spectra of 98Tc and 9 3Ru," PRAMANA (inpress).

3. Kamble V. B. and Khadkikar S. B.; "Structureof 1 SC with density independent Skyrme inter-action," Phys. Lett. 59B, 19 (1975).

4. Khadkikar S. B. and Nair S. C. K.; "A generatorcoordinate approach to the breathing mode,"Phys. Lett. 57B, 225 (1975).

5. Khadkikar S. B.; 'Clusters and Correlations inNuclei," Proceedings of the conference onGeneral Many Body Problem edited by R.Pratap and J. C. Parikh and published byHindustan Publishing Corporation, Delhi 165(1975).

6. Mugambi P. E. and Sharma S. K.; "On theangular momentum dependence of the varianceof the projected Hartree-Fock wave functions,"ICTP Trieste, Internal Report IC/75/70.

7. Potbhare V. and Pandya S. P.; "Ground stateoccupancies and effective interactions in s-dshell nuclei," Nuclear Physics A 256,253 (1976).

8. Sharma S. K.; "On the microscopic descriptionof the Yrast states in even-even 2p-1f shellnuclei," Nuclear Physics A (in press).

9. Sharma S. K., Satpathy L, Khadkikar S. B. andNair S. C. K.; "On the validity of the crankedHartree-Fock approximation," Physics LettersB (in press).

10. Sharma S. K.; "Magnetic moment of 5 7 Ni , "submitted to Physics Letters B.

11. Sharma S. K.; "Shape mixing and the emer-gence of vibrational spectra in some even-even2p-1f shell nuclei : An illustration in 53Fe,"Submitted to the Physical Review C.

III. PLASMA THEORY

1. Buti B. and Lakhina G. S.; "Stability of solarwind double-ion-streams," J. Geophys. Res. (inpress).

2. Buti B.; "Relativistic electron gas," Proceedingsof General Many Body Problem edited by R.Pratap and J. C. Parikh and published by Hin-dustan Publishing Co. (1975).

3 Buti B.; "Drift instabilities in Antiloss-coneplasmas," J. Plasma Physics, 15, 105 (1976).

4. Buti B.; "Anti-loss cone instability in magneto-sphere," (to appear in J. Geophys. Res.)

5. Buti B.; "Modulational instability of ion acousticwaves in collisional plasmas," J. Plasma Physics(in press).

6. Buti B.; "E. M. Drift instabilities in high-/3Antiloss-cone Plasmas," to appear in J. PlasmaPhysics.

7. Buti B. and Sharma A. S.; "Collisional excita-tion of modulational instability in Langmuirturbulence," (to appear in Journal of PlasmaPhysics).

8. Goswami B. N. and Buti B.; "Cross-field-current driven electrostatic instabilities in plas-mas with generalized distribution functions,"Nucl. Fusion, 15, 991 (1975).

9. Goswami B. M. and Buti B.; "Nonlinear drift -dissipative instability in collisional plasmas," (toappear in Plasma Phys.).

10. Guzdar P., Sen A., and Kaw P. K.; "Excitationand suppression of kink modes by coupling toion acoustic waves," Nucl. Fusion, 15, 1007(1975).

11. Guzdar P. and Sen A.; "Modulational instabilityin the presence of Langmuir turbulence". (Toappear in Phys. Letts. A.).

12. Guzdar P., Sen A. and Kaw P.; "StimulatedRaman scattering in a plasma with randomdensity fluctuations," (submitted for publication).

13. Kulkarni V. H. and Das A. C; "Resonant inter-action of an electromagnetic test wave withelectrons trapped in an electrostatic wave," (toappear in Phys. of Fluids).

14. Prasanna A. R.; "Static Fluid Spheres inEinstein-Cartan Theory,". Phys. Rev. D11, 2076(1975).

15. Prasanna A. R.; "Static Cylinder of perfect fluidwith non-zero spin density," Phys, Rev. D112083 (1975).

16. Prasanna A R; "Maxwell's equations in Rie-mann-Cartan" Space U4" Phys. Letts. 54A, 17(1975).

17. Prasanna A. R.; "Cylindrically symmetric matterdistribution with magnetic field in Einstein-Cartan Theory," Pramana 5, 289 (1975).

19. Sen A. and Sundaram A. K.; "Feedback supp-ression of dissipative trapped particle instabili-ties by neutral beam injection," Nucl. Fusion16 (1976).

20. Sharrna A. S. and Buti B.; "Nonlinear saturationof Hot Beam-Plasma Instability." (to appear inPramana).

21. Sharma A. S. and Buti B.; "Envelope solitonsand holes for Klein-Gordon and Sine-Gordonequations" (to appear in J. Phys. A).

38

22. Sharma A. S. and Buti B.; "ModulationsI insta-bility and envelope solutions of nonlinear dis-persive wave equations," (to appear in J. Math.Phys.).

23. Sinha M. and Sundaram A. K.; "Velocity shearinduced flute instabilities in plasmas," (to appearin Journal of Plasma Physics, (1975).

24. Sinha M. and Sundaram A. K.; "On the trigger-ing of an isolated magnetic substorm : A theory,"Geophys. Letters, 3, 57 (1976).

25. Sundaram A. K. and Sen A.; "Influence of aHigh Frequency Pump on Trapped ParticleModes," (to appear in Journal of PlasmaPhysics) (1976).

26. Varma R. K.; "Particle transport due to thepolarization of trapped particles by the inductionelectric field in a Tokamak," Proc. of VII Euro-pean Conference on Controlled Fusion andPlasma Physics, Lausanne, Switzerland, Sept.1-6, (1975).

27. Varma R. K.; "Interaction of neutral gas witha moving magnetized plasma," (submitted toJ. Plasma Physics).

IV. LABORATORY PLASMA AND ASTROPHYSICS

1. Alexeff I., John P. I. and Saxena Y. C; "Non-linear splitting of ion rarefaction waves,"(Communicated to lEE-Trans. Plasma Science).

2. John P. I. and Saxena Y. C; "LaboratoryObservations of Farley-Bunemann Instability,"Proc. 12th International Conference on thePhenomena in Ionized gases, Eindhoven p. 302(1975).

3. John P. I. and Saxena Y. C; "An experimentalsystem for laboratory simulation of equatorialelectrojet instabilities," Indian J. Radio and Spa.Phys. 4, 267 (1975).

4. John P. I. and Saxena Y. C; "Propagation ofion acoustic solitonsat plasma density gradients,"(to appear in Phys. Letters).

5. Saxena Y. C. and John P. I.; "Observation ofthe crossfield instability in laboratory plasma,"Geophys. Res. Lett. 2, (492) 1975.

V. GEOCOSMOPHYSICS

1. Amin B. S., Lai D., and Somayajulu B. L. K.;"Chronology of marine sediments using the1 0 Be method : intercomparison with other me-thods," Geochim. Cosmochim. Acta, 39, 1187-1192 (1975).

2. Bhandari N., Bhattacharya S. K. and Padia J. T.;"Surface radioactivity of lunar rocks : implica-tions to the solar activity in the past," Proceed-ings of the VI Lunar Science conference, Geo-chim. Cosmochim. Acta, 2, 1913 (1975).

3. Bhandari N., Gopalan K. and Rao M. N.;"Exposure and formation history of the Parsameteorite based on fossil track and rare gasstudies," J. Meteoritical Society, 10, 362 (1975).

4. Bhattacharya S. K. and Bhandari N.; "Effectsof exposure conditions on cosmic ray recordsin lunar rocks," Proceeding of VI Lunar ScienceConference, Geochim. Cosmochim. Acta, 2,1901(1975).

5. Bhattacharya S. K., Goswami J. N., Lai D.,Patel P. P. and Rao M. N.; "Lunar regolithand gas-rich meteorites : characterization basedon particle tracks and grain size distribution,"Proceedings of VI Lunar Science Conference,Geochim. Cosmochim. Acta, 3, 3509 (1975).

6. Gopalan K. and Rao M. N.; "Rare gas studiesof Allende and St. Severin meteorites and theirimplication with reference to curium-248," J.Meteoritical Society; 10, 410 (1975).

7. Goswami J. N., Lai D. and Rao M. N.; "Compo-sitional studies of solar-iron group and heaviernuclei of kinetic energy below 10 MeV(nucleon)," Proceedings of the VI Lunar ScienceConference, Geochim. Cosmochim. Acta 3,3541 (1975).

8. Krishnaswami S., Somayajulu B. L. K., andChung Y.; " 3 1 0 Pb/ 9 3 c Ra disequilibrium in theSanta Barbara basin," Earth Planet. Sci. Lett.27, 338 (1975).

9. Krishnaswami S., Lai D., Somayajulu B. L. K.and Craig H., "Large volume in-situ filtrationof deep Pacific waters : mineralogical andradioisotope studies," Earth Planet. Sci. Lett.(Special Issue) (1975).

10. Krishnaswami S., Lai D., Somayajulu B. L K.and Craig H.; "Investigations of gram quantitiesof Atlantic and Pacific surface particulates,"Earth Planet. Sci. Lett. (Special Issue) (1975).

11. Lai D. and Somayajulu B. L. K., "Paniculatetransport of radionuclides 1 4C and 55Fe todeep waters in the Pacific Ocean," LimnologyOceanography (1975) (in press).

12. Lai D., Nijampurkar V. N., Somayajulu B. L. K.,Koide M. and Goldberg E. D., "Silicon-32specific activities in the coastal waters of theworld oceans," Limnology & Oceanography,21, 287-295, 1976.

39

13. Lai D. and Somayajuiu B. L. K., "On theimportance of studying magnetic susceptibilitystratigraphy and geochronology of lake Biwasediments," in Paleolimnology and the JapanesePleistocene (ed. S. Horie), 3, 530-535, 1975.

14. Prabhawalkar P. D., Raghunathan V. S. andRanganathan S., "Computer simulation of Field-ion Image from Interstitial Alloys," in SurfaceScience, 51, 441-450, 1975.

VI. ARCHAEOLOGY-HYDROLOGY

1. Agrawal D. P. and Kusumgar S.; "Tata InstituteRadiocarbon Date List XI," Radiocarbon, 17,No. 2, (1975).

2. Agrawal D. P., Krishnamurthy R. V., KusumgarS. and Pant R. K.; "Physical Research Labora-tory Radiocarbon Date List I," Radiocarbon,18, pp. 89-95 (1976).

3. Agrawal D. P. and Kusumgar S., "RadiocarbonDates of Neolithic-chalcolithic samples," CurrentScience, 44, No. 9, (1975).

4. Agrawal D. P., Krishnamurthy R. V., KusumgarS. and Pant R. K.; "Radiocarbon Dates" IndianArchaeology - A review, 1974-75. (In Press).

5. Agrawal D. P., Kusumgar S. and Pant R. K.;"Radiocarbon and Indian Archaeology," PhysicsNews, (1975).

6. Agrawal D. P., Margabandhu C. and ShekarN. C; "Ancient gold workings : Some new 1 4Cdates," Journal of History of Science (in press).

7. Agrawai D. P., Margabandhu C. and ShekarN. C; "Ancient Copper workings : Some new1 4C dates," Journal of History of Science (inpress).

8. Singh G. and Agrawal D. P.; "Radiocarbonevidence for delegation in N. W. Himalaya,"Nature, 210 (1976).

9. Sehra P. S.; "Upper atmospheric thermal struc-ture in Antarctica" Nature, 254, 401 -404, (1975).

10. Sehra P. S.; "Structure of the Atmosphere overSouth Polar and Equatorial Regions," J.Meteorological Society of Japan 54, pp. 13,(1976).

11. Sehra P. S.; "Atmospheric Structure: Explora-tion over Antarctica and Equatorial Comparison,"Indian J. Radio Spa. Phys. 5, pp. 66-74, (1976).

12. Sehra P. S.; "Antarctic Atmosphere : Tempera-ture Exploration and its seasonal variations,"Oceans and Atmospheres, J. Geophys. Res.(in press).

VII. TECHNIQUES AREA

1. Rawat S. D.; "Departure from the Kundsen'sCosine Law during Boat Evaporation of Indium,"J. Vac. Sci. Technol. (USA), Vol. 12, p. 725(May/June, 1975).

VIII. COMPUTER CENTRE

1. Desai S. G.; "Conversion of 7090 Data to 360Data," Common (Europe), Vol. 39, Jan. 1973,Cast No. 53/54.

2. Desai S. G.; "Map language for 1620 computer,"Common (Europe), Vol. 1, April 1975, CastNo. 74/75.

3. Desai S. G.; "Paper Tape Routine for DOS360," Common (Europe), Vol. 3, October 1975,Cast No. 78/79/80.

4. Desai S. G.; "Routine for ASCII Paper tapeunder DOS 360," Common (Europe), Vol. 3,Oct. 1975, Cast No. 78/79/80.

5. Desai S. G.; "Routine Accounting under DOSon 360 computers," CSI Newsletter Vol. 11, Dec.1975, No. 6.

6. Murthy C. S. R.; "A Clustering Technique," CSIJournal Vol. 5, No. 1 (1974).

40

PAPERS PRESENTED ATSYMPOSIA AND CONFERENCES

IN 1975-76

I. SOLAR AND PLANETARY PHYSICS

a. Presented at Solar Planetary Physics Symposium,Ahmedabad, January 20-24, 1976.

1. Ananth A. G. and Rao U. R., "The convectionand diffusion concept of cosmic ray diurnalvariation."

2. Anandarao B. G. and Raghavarao R., "Effect ofgravity wave winds on the electrojet."

3. Anandarao B. G. and Raghavarao R., "Electricfields in the equatorial ionosphere."

4. Bhonsle R. V., Alurkar S. K., Sawant H. S. andNarayanan K., "Measurement of ionosphericelectron content at 40 MHz and scintillationsat 40 and 860 MHz using ATS-6 transmissionsat Ahmedabad."

5. Deshpande M. R., Rastogi R. G., Banshidhar,Vadher IV. M., Jair A. R., Rai R. K., Gurm H. S.and Subbarao B. S., "Multistation measurementof total electron content and travelling ionos-pheric disturbances using ATS-6 radio beacon."

6. Jain A. K., Jayanthi U. B., Rao U. R., SharmaD. P. and Kasturirangan K., "Long term inten-sity variations of Cyg X-1 at energies greaterthan 20 KeV."

7. Kulkarni P. V., "Optical emissions in the upperatmosphere - A review."

8. Majumdar N. H. and Kulkarni P. V.; "Preliminaryresults of the temperature measurement in the90 km region from ground-based night airglowmeasurements."

9. Raghavarao R., "The equatorial F-region dyna-mics - A possible mechanism for the counter -electrojet".

10. Raghavarao R. and Sharma P., "Lunar controlover the intensity and occurrence of the equa -torial ionisation ledges."

11. Raghavarao R., Sharma P. and Jain A. R.,"lonisation ledges and the counter-electrojet inthe equatorial ionosphere."

12. Raghavarao R., Sharma P. and Sivaraman M. R.;"lonisation ledge : A tool to detect cross-equatorial wind at F-region altitudes."

13. Raghavarao R., Sharma P. and Sivaraman M. R.,"Estimation of neutral anomaly strength from theionisation anomaly."

14. Raghavarao R. and Sharma P., "Spread-F inthe topside ionosphere."

15. Raja ram G., Das A. C. and Rastogi R. G.,"Response of mid-latitude plasma trough tomagnetic storms."

16. Rajaram G., Das A. C. and Rastogi R. G.,"Dawn-dusk features of electron density andelectron temperature in the exosphere."

17. Rastogi R. G. and Iyer K. N., "Total electroncontent over Indian sub-continent."

18. Rastogi R. G. and Deshpande M R., "Measure-ments of phase and amplitude scintillations atOotacamund using ATS-6 Satellite".

19. Rastogi R. G., Vyas G. D. and Devanathan S. N.,"E-region ionospheric irregularity investigationin the equatorial electrojet region."

20. Rastogi R. G., "Spread-F" (review talk).

21. Sastry T. S. G., Burrows K. and Sampath S.,"Equatorial electrojet during the early main phaseof magnetic storm."

22. Sastry T. S. G., Sartiel J. and Sampath S., "Nearsimultaneous measurements of electric field andthe current density in the equatorial electrojet."

23. Sastry T. S. G. and Sampath S., "Day-to-dayvariability of equatorial eiectrojet as observedby rocket-borne magnetometers."

2<. Satya Prakash and Muralikrishna P., "E and Fregion electric fields over the dip equator."

25. Sawant H. S., Alurkar S. K. and Bhonsle R. V.,"High resolution observations of the November1975 decametric solar noise storm."

26. Shirke J. S. and Degaonkar S. S., "East-westand north-south asymmetries in the annual andsemi-annual component in NmF2."

27. Shirke J. S., and Ganguly S., "Similarities inGeomagnetic control on D and F region ionisa-tion and possible coupling mechanism."

28. Shirke J. S. and Pradhan S. N., "Horizontalscale sizes of ionospheric irregularities in theequatorial ionosphere."

29. Shirke J. S., Sridharan R., Das S. R., PokhunkovA. D., Semenov V. K. and Danilov A. D.,"Simultaneous measurement of neutral and ioncomposition at dip equator."

30. Subbaraya B. H., Pareek P. N., Satya Prakashand Vijay Kumar, "Direct and scattered Lymanalpha measurements in the morning twilight atThumba."

41

31. Subramanian G., "Cosmic ray modulation - Areview."

32. Degaonkar, S. S. '.'Solar X-rays - A review."

b. Presented at the Solar Physics Symposium,Udaipur, 1975.

c. Presented at Equatorial Geomagnetic PhenomenaSymposium, I.I.G. Bombay, 1975.

33. Muralikrishna P. and Satya Prakash, "lonizationirregularities in the counter-electrojet."

34. Rastogi R. G., "Counter-electrojet" review paper.

d. Presented at the COSPAR Symposium held atVerna, Bulgaria, 29-31 May 1975.

35. Rao U. R., Kasturirangan K., Sharma D. P.,Jain A. K. and Jayanthi U. B., 'Balloon observa-tions of fast intensity fluctuations and flare-likeenhancements of X-ray emissions from Cyg X-1. "

36. Kulkarni P. V., "Rocket study of 5577 A 01emission at the night over the magnetic equator."

37. Desai J. N., Bhavsar P. 0. and Narayanan M. S.,''Winds in the lower thermosphere as measuredby vapour release."

38. Desai J. N., Rees D., Bhavsar P. D., Gupta S.P. and Rounce P., "Preliminary report oncommonwealth collaborative programme fromTERLS."

e. Presented at the URSI General Assembly Meet-ing at Lima, Peru, August 1975.

39. Desai J. N., Anandarao B. G., Bhavsar P. D.,Martelli G., Raghavarao R. and Rothewel P.,"Electric fields in the equatorial ionosphere."

40. Deshpande M. R., Singh B. and Rastogi R. G.,"Characteristics of E-region irregularities overthe magnetic equatorial region during magneticstorms."

41. Rastogi R. G. and Deshpande M. R., "Spread-Firregularities near the magnetic equator."

42. Rastogi R. G. and Deshpande M. R., "Equatorialirregularities as seen through VHF scatterrecords."

43. Rastogi R. G., "Equatorial Sporadic E-thejr-properties."

44. Rastogi R. G. and Iyer K. N., "Upwardmovjngirregularities over the magnetic equator."

45. Rastogi R. G. and Iyer K. N., "Contours of totalelectron content over the Indian subcontinent."

46. Rastogi R. G. and Deshpande M. R., "Ionos-pheric drifts at low latitudes in the Indiansub-continent."

47. Satya Prakash, Muralikrishnan P. and SubbarayaB. H., "Direct and scattered Lyman alpha mea-surements in morning twilight at Thumba."

f. Presented at IAGA Assembly held at Grenoble,France, during 24th Aug. - 6th September 1975.

48. Kulkarni P. V., "Night airglow 5577 A (01)emission observed over the magnetic equatorby a rocket photometer."

49. Kulkarni P. V. and Rao V. R., ''Absolute inten-sity of determination of the emission bands innight airglow with filter photometer."

g. Presented at the Symposium on Ionosphere -Magnetosphere Interaction N.P.L, New DelhiFeb. 1975.

50. Sivaraman M. R., Suhasini R. and RaghavaraoR., ''The role of ambipolar diffusion in thedevelopment of the equatorial anomaly in solarmaximum and minimum periods."

h. Presented at the Summer Meeting of Societyof Terrestrial Magnetism and Electricity, Japan,May 1975.

51. Rajaram G., "Asymmetry in plasma trough struc-ture between European and American sectors."

i. Presented at the Symposium on Ionosphere andMagnetosphere, Andhra Univ,Waltair, Jan. 1976.

52. Rastogi R. G., 'Counter equatorial electrojet &its effect on the ionosphere" review paper.

II. THEORETICAL PHYSICS

NUCLEAR THEORY

a. Papers presented at the Nuclear Physics andSolid State Physics Symposium, Calcutta,December 22-26, 1975.

1. Ahalpara D. P. and Bhatt K. H., "Shell modelspectra of " T c and 9 3Ru."

2. Dhar A. K. and Bhatt K. H., ''Structure of *9Tiand 49Cr."

3. Dhar A. K., Kulkarni D. R. and Bhatt K. H.,"Electromagnetic Transitions in 4 7 Ti . "

4. Kamble V. B. and Khadkikar S. B., "ProjectedMultishell Hartree-Fock calculations for someA=8 nuclei with density independent Skyrmeinteraction."

5. Kamble V. B., Khadkikar S. B. and Kulkarni D. R.,"Structure of * * B and i a C with modified Sussexinteraction."

6. Kulkarni D. R., Khadkikar S. B. and PandyaS. P., "Generator co-ordinate spectrum of 5 CNi" .

42

7. Praharaj C. R. and Khadkikar S. B., "Hartree-Fock calculations for Mercury isotopes."

8. Sharma S. K., Satpathy L, Khadkikar S. B. andNair S. C. K., "On the validity of cranked Har-tree-Fock approximation."Trivedi H. P. and Khadkikar S. B., "Alpha-alpha9.scattering with a Skyrme Interaction."

b. Papers contributed to the International TopicalConference on Effective Interactions and Opera-tors in Nuclei, University of Arizona, Tucson,June 2-6, 1975.

10. Ahalpara D. P. and Bhatt K. H.," A note ond 3 y 3 - f 7 / 3 Empirical Interaction".

11 . Dhar A. K. and Bhatt K. H., "Semi-empiricaltrimming of effective interactions in the fp shell".

c. Presented at the Conference on "Current Trendsin Physics," Institute of Physics, Bhubaneswar,Feb. 16-21, 1976.

12. Pandya S. P., "Statistical Methods in NuclearStructure."

PLASMA THEORY

a. Papers presented at the Solar Planetary PhysicsSymposium, Ahmedabad, January 20-24, 1 976.

1 . Kulkarni V. H. and Das A. C, "Side bandgrowth in the whistler mode packet and VLFemissions."

b. International Symposium on Relativity and Uni-fied field Theory, Calcutta, December 26,1975 -January 1 , 1 976.

2. Prasanna A. R., "Einstein - Cartan Theory"(Invited Paper).

c. International Conference on Statistical Physics,Budapest, August 25-29, 1975.

3. Pratap R., "Stochastic Lagrangian Formulationof Dynamics of an Electron Plasma."

d. VII European Conference on Controller Fusion

and Plasma Physics, Lausanne, Switzerland,September 1-6, 1975.

4. Varma R. K., "Particle Transport due to thepolarization of trapped particles by the induc-tion electric field in a Tokamak."

e. Marcel Grossmann Meeting on "Recent Pro-gress of the Fundamentals of General Theoryof Relativity, ICTP Trieste, Italy, July 7-12,1975.

5. Prasanna A. R., "Solutions of Einstein - CartanEquations."

III. LABORATORY PLASMA AND ASTROPHYSICS

a. Presented at the Solar Planetary Physics Sym-posium, Ahmedabad, January 20-24, 1976.

1. John P. I. and Saxena Y. C, "LaboratorySimulation of Electrojet Instabilities."

b Presented at the First Topical Conference onDiagnostic of High Temperature Plasmas:Knoxville, 1975.

2 Alexeff I., John P. I. and Saxena Y. C, "Asimple high speed auto and cross correlator."

IV. GEOCOSMOPHYSICS

a. Papers presented at the Solar Planetary PhysicsSymposium, Ahmedatad, January 20-24, 1976.

1. Bhattacharya S. K. and Bhandari N., "Modula-tion of galactic cosmic rays from the study ofcosmogenic radioisotopes in meteorites."

2. Jayanthi U. B. and Mattoo S. K. "Compositionand energy spectrum of heavy nuclei - Resultsfrom Skytab experiment."

b. Papers contributed to the VII Lunar Science

Conference, Houston, 1976.

3. Bhandari N., Bhattacharya S. K. and Padia J. T.,'/Solar flare records in lunar rocks."

4. Gopalan K. and Rao M. N., "Solar cosmic rayeffects in heavy noble gases of lunar soils andbreccias."

5. Lai D. and Rao M. N., "Some complex butinteresting aspects of solar and galactic cosmicray irradiation of lunar regolith."

c. Papers presented at the XIV International CosmicRay Conference, Munich, 1975.

6. Bhandari N. and Bhattacharya S. K., "Shape ofthe solar flare proton spectra in 10-100 MeVregions in the past."

7. Gopalan K. and Rao M. N., "Enhanced Solarcosmic ray flux in the early solar system."

d. Presented at the VI International Seminar onSolar Particle Fluxes and Radiation Belts ofEarth and Jupiter, Leningrad, 1975.

8. Bhandari N., "Long term variation of cosmicrays."

e. Presented at the Royal Society Meeting on TheMoon - A new appraisal from space missionsand laboratory analysis, London, 1975.

9. Lai D., "Irradiation and accretion of solids inspace based on observations of lunar rocks andgrains."

43

f. Paper contributed to the Workshop on Palaeo-climate and Archaeology of Rajasthan andGujarat Ahmedabad, 1976.

10. Bhandari N., ''The climate paradox in astro-physical perspective."

11. Somayajulu B. L. K., "Palaeoclimates : old andnew ideas.

g. Presented at Geology session of the 63rd IndianSc. Congress, held at Andhra Univ., Jan 1976.

12. Krishnaswamy S.. " Biography of transition metalsin the ocean."

h. Presented at the 27th session. Geochemistry ofthe Sea, 16th IUGG General Assembly, Grenoble,France (1975).

13. Krishnaswami S., Lai D. and Somayajulu B. L. K.,"Particles in the ocean : their composition androle in regulating trace element, marine geo-chemistry."

i. Presented at Indo-German Workshop on Appro-aches and Methodologies for Development ofGround water Resources, held in N.G.R.I., Hyde-rabad May 26-30 (1975).

14. Somayajulu B. L K. and Nijampurkar V. N.,''Dating ground waters using silicon-32."

V. ARCHAEOLOGY-HYDROLOGY

a. Papers presented at the Workshop on Palaeo-climate and Archaeology of Rajasthan andGujarat, Ahmedabad, February 23-26, 1976.

1. Agrawal D. P. and Roy B., "The Miliolite Pro-blems : some new SEM and other analyticaldata."

2. Gupta S.K.; "History of Holocene Sedimentationin the Little Rann of Kutch."

3. Gupta S. K., "Quartemary Sea Level Changeson the Saurashtra Coast."

4. Roy B. and Merh S. S., "Geomorphology ofRann of Kutch and Climatic Changes."

b. Paper submitted at the Annual Convention ofInstitute of Engineers, Ahmedabad, January 1976.

5. Ramanathan K. R., "Water supply problems ofAhmedabad and the related ground water pro-blems in Sabarmati basin."

c. Paper presented at the Inaugural meeting ofIndian Water Works Association, Ahmedabad,July 27, 1975.

6. Shah S. R., "Ground water problems ofAhmedabad."

d. Presented at the seminar on sub surface investi-gations and foundation analysis, Institute ofEngineers (India), 1975.

7. Shah S. R., "Case study interference andhydraulic connections of acquifers."

e. Presented at the Workshop on the Problemsof desert in India, Jaipur, 1975.

8. Agrawal D. P., "Palaeoclimate and geochro-nology of the arid regions of India : somesuggestions."

f. Paper presented at the Indo-German Workshop,Hyderabad, May 1975.

9. Gupta S. K., "Radiocarbon dating of groundwater."

g. Presented at the conference on nuclear tech-niques in hydrology at Poona, 1975.

10. Ramanathan K. R., "Problems of Ground waterhydrology in Gujarat and potentialities of groundwater techniques for better understanding andmanagement of water resources."

h. Presented at the International low-level radio-activity conference. High Tatras, 1975.

11. Kusumgar S. and Agrawal D. P., "Magnitudeof 1 4 C/ 1 2 C variations based on archaeologicalsamples."

i. Presented at the Symposium on Basic Sciencesand Agriculture, Indian Academy of Sciences,New Delhi, Octob&r 11-13, 1975.

12. Pisharoty P. R., "Remote Sensing and Agricul-ture."

j . Contributed to the Indian Science CongressAssociation, January 1976.

13. Pisharoty P. R., "ISRO's research on applica-tion of Space Technology to Meteorology andWater Management."

k. Presented a paper at the Seminar/Group dis-cussions on Role of Photo-interpretation andRemote Sensing in Natural Resources Surveyand Development Plans, Nagpur, March 1976.

14. Pisharoty P. R., "The Key Note paper onRemote Sensing."

I. Paper contributed to the UN-SAO Seminar onRemote Sensing Applications, November 1975.

15. Pisharoty P. R., "Remote Sensing and Clouds".

VI. COMPUTER

Presented at 11th C.S.I, convention at Hyderabad.1. Murthy C. S. R., "An algorithm for scheduling

activities when there are constraints on morethan one resource."

VII. ENGINEERING

1. Sonpal R. C. and Panchal B. L, "Load Teston Model Concrete Piles," presented at FifthAsian Regional conference on soil Mechanicsand Foundation Engineering, December 19-22,1975, held at Indian Institute of Science,Bangalore.

44

THESES SUBMITTED DURING 1975-76

1. Ananth A. G., "Time variation of Cosmic Ray Intensity," thesis submitted to the Gujarat Universityfor Ph.D. degree; supervised by Prof. U. R. Rao.

2. Haq. Ft., "Application of distribution methods to symmetries in Nuclei;" thesis submitted to theGujarat University for Ph.D. degree; supervised by Dr. J. C. Parikh.

3. Kulkami V. H., "Studies in Wave-particle interactions;" thesis submitted to the Gujarat Universityfor Ph.D. degree; supervised by Dr. A. C. Das.

4. Satya Y. S., "Modification of low frequency waves by oscillating fields;" thesis submitted to theGujarat University for Ph.D. Degree; supervised by Prof. P. K. Kaw.

5. Vyas N. K.; ''Studies of low frequency instabilities in a collisionless plasma;" thesis submittedto the Gujarat University for Ph.D. degree; supervised by Dr. A. C. Das.

BOOKS AND REVIEWS

a) Books

1. Degaonkar S. S., "An introductory course in space science and earth's environment;" publishedby the Gujarat University for the space science and earth's environment course.

b) Review

1. Kane R. P., "Geomagnetic field variations". Space Science Reviews 18, 413, (1976).

2. Bhonsle R. V., Degaonkar S. S. and Alurkar S. K., "Groundbased solar radio observations ofthe August 1972 events", to appear in Space Science Reviews, (1976).

45

CONFERENCES/SYMPOSIA ATTENDED BY PRLSCIENTISTS IN INDIA AND ABROAD DURING

1975-76

SOLAR AND PLANETARY PHYSICS

Dr. J. S. ShirkeVerna, Bulgaria

Dr. J. N. DesaiVerna, Bulgaria

Dr. B. H. SubbarayaGrenoble, France

Dr. S. K. AlurkarBombay

Mr. Yashwant AcharyaBangalore

Dr. S. K. AlurkarProf. R. V. BhonsleDr. S. S. DegaonkarMr. H. S. SawantDr. G. SubramanianUdaipur

Ahmedabad

Professor R. G. RastogiBombay

Lima

Boulder

Waltair

Ahmedabad

Dr. M. R. DeshpandeAhmedabad

Dr. G. RajaramTokyo

Tokyo

Ahmedabad

COSPAR Meeting, 29th May to 7th June, 1975.

COSPAR Meeting, 29th May to 7th June, 1975.

IAGA/IUGG Meetings, Aug.-Sept, 1975.

Annual IEEE Convention and exhibition 1976 as well asthe Tutorial cum Workshop on Signal Processing,February 1976.

Intensive course on "Digital Equipments," 9-21 February,1976.

Solar Physics Symposium, September 20-22, 1975.

Solar Planetary Physics Symposium, January 20-24,1976.

Symposium on "Equatorial Geomagnetic Phenomena" atthe Indian Institute of Geomagnetism, Bombay, from 15thto 16th May, 1975.XVIllth General Assembly of URSI, Lima, Peru, from 8thto 19th August 1975.Annual Meeting of USNC-URSI, Boulder, USA on 20thSeptember, 1975.Symposium on "Ionosphere and Magnetosphere" atAndhra University, Waltair, January 7-9, 1976.Symposium on "Solar Planetary Physics" at PRL, Ahme-dabad, from 20th to 24th January 1976.

Symposium on "Solar Planetary Physics" at PRL,Ahmedabad, from 20th to 24th January, 1976.

Summer meeting of Japanese Society of TerrestrialMagnetism and Electricity, May 1975.Seminar on Solar Terrestrial Relationships at Instituteof Space and Aeronautical Sciences Jan. 1975.Solar Planetary Physics Symposium, January, 1976.

46

THEORETICAL PHYSICS(i) NUCLEAR THEORY

Dr. J. C. ParikhStrasbourg

Glasgow

Dr. S. K. SharmaJuelich, West Germany

Dr. S. B. KhadkikarMr. D. P. AhalparaMr. A. K. DharMr. V. B. KambleCalcutta

Prof. S. P. PandyaDelhi

BhubaneswarAhmedabad

(ii) PLASMA THEORY

Professor B. Buti

Bombay

Ahmedabad

Prof. R. K. Varma

Budapest

Lausanne

Prof. R. PratapBudapestBangalore

Bombay

Ahmedabad

Dr. A. C.Ahmedabad

ProfessorDr. A.Dr. S.Dr. A.Mr. B.Mr. A.Bombay

C.B.

Das

R. K. VarmaDasKhadkikar

SenN.S.

GoswamiSharma

Conference on Statistical Approach to Nuclear Physics,University of Strasbourg, November 1975.Small scale conference on Large Scale Shell ModelCalculations, August 1975.

Symposium on Highly Excited States in Nuclei, Juelich,September 1975.

Nuclear Physics and Solid State Physics Symposium,December 1975.

International Conference on Few Body Problems, Dec.1975.Conference on Current Trends in Physics, Feb. 1976.Seminar on New Energy Sources for Second India atthe 8th Engineers Day, September 1975.

Symposium on Equatorial Geomagnetic Phenomena atIndian Institute of Geomagnetism, May 1975.Symposium on Solar Planetary Physics held at PRL,January 20-24, 1976.

International Conference on Statistical Physics, August25-29, 1975.European Conference on Controlled Fusion and PlasmaPhysics, Sept. 1-6, 1975.

International Conference on Statistical Physics, August25-29, 1975.Geophysical Fluid Dynamics Workshop held at the Centrefor Theoretical Studies, Indian Institute of Science, July1975.Symposium on equatorial Geomagnetic Phenomena, May1975.Workshop on Paleoclimate and Archaeology, February1976.

Solar Planetary Physics Symposium, January 20-24,1976.

Winter School in High Energy Astrophysics.

47

LABORATORY PLASMA AND ASTROPHYSICS

Dr. Y. C. SaxenaEindhoven,The Netherlands

GEOCOSMOPHYSICS

Prof. D. LaiLondon

Munich(West Germany)Grenoble (France)

Miami (USA)

Dr. N. BhandariLeningrad (USSR)

Dr. M. N. RaoTours (France)

Munnich (W. Germany)

Bern (Switzerland)Heidelberg, Mainz and Cologne

Dr. B. L. K. SomayajuluGrenoble (France)

Paris (France)

Copenhagen (Denmark)

Pisaf(ltaly)

Dr. S. KrishnaswamiWaltair

Mr. S. K. Bhattacharya

Houston (USA)

ARCHAEOLOGY-HYDROLOGY

Dr. S. K. GuptaGraz, AustriaHyderabad

XII International Conference on Phenomena in Ionizedgases, 18-22 August, 1975.

Royal Society Discussion Meeting on "The Moon" during9-11 June, 1976 and presented an invited paper.14th International Cosmic Ray Conference, 18th to 25thAugust, 1975.16th General Assembly of the International Union ofGeophysics and Geodesy 25th August to 5th September,1975 and presented a paper.Workshop on Tropospheric Transport of Pollutants to theOcean.

Symposium on Solar particle fluxes and radiation beltsof Earth and Jupiter, May 1975 and presented a paper.

38th Meteoritical Society Meeting in June 1975 andpresented three papers.14th International Cosmic Ray Conference between 18thand 25th August, 1975 and presented a paper.Visited the Physikalisches Institute.Visited the Max-Planck Institut fur Kernphysik, Max-Planck Institut fur Kernchemie and University of Cologne.

16th General Assembly of the International Union ofGeophysics and Geodesy between 25th August and 5thSeptember 1975 as Deputy Secretary of IAPSO.Spent three weeks at the Laboratoire de Geologie work-ing on lake Pavin.Visited the Isotope Laboratory of Prof. Dansgaard duringSeptember 1975.Visited the Laboratorio Geologio Nucleare during October1975.

63rd Session of the Indian Science Congress held inthe Andhra University to receive the Young Scientists'Award. Presented a paper in the Geology Session.

VII Lunar Science Conference in March 1976 andpresented a paper.

Post-graduate training course on ground water tracingtechniques, 25 Aug. - 24 Sept., 1975.Indo-German workshop on "Approaches and Methodo-logies for development of ground water resources,"26-30 May, 1975.

48

Mr. S. R. ShahRoorkee National Symposium in Hydrology in December 1975.

Miss S. KusumgarCzechoslovakia

Professor K. R. Ramanathan

Hyderabad

Bangalore

Delhi

Alexandria

Prof. P. R. Pisharoty

New Delhi

Nagpur

Grenoble, France

Tokyo, Japan

International Low level Radioactivity Conference, Sep-tember, 1975.

Symposium/Workshop on approaches and methodologiesof ground water resources, 26-30 May, 1975.

Geophysical Fluid Workshop monsoon meteorology,8-18 July, 1975.

Seminar on 2nd World Congress on Water Resources,12-16 December, 1975.

International Symposia on Arid Land Irrigation in Deve-loping Countries, 16-21 February, 1976.

Symposium on Basic Sciences and Agriculture, 11-13October, 1975.UN-SAO Seminar on Remote Sensing Applications,November 1975.Indian Science Congress Association, January 1976.

Seminar/Group Discussions on Role of Photo-interpreta-tion and Remote Sensing in Natural Resources Surveyand Development Plans, March 1976.

Joint lAMAP-IAGA Symposium on Stratosphere-Mesos-phere Relations.XVI General Assembly of IUGG,25th August to 5th September 1975.

Eleventh Session of the Joint Organising Committee ofthe WMO/ICSU for GARP, October 1-8, 1975.

COMPUTER CENTRE

Mr. P. S. ShahMr. C. S. R. MurthyDr. Rao S. KoneruDr. D. R. Kulkarni

Hyderabad

Mr. P. S. ShahHyderabad

Dr. D. R. KulkarniMr. G. G. DholakiaAhmedabad

11th Convention of Computer Society of India in February1976.

A course on "EDP" Management conducted by ComputerSociety of India at Hyderabad.

A Course on "Compiler Programming" conducted by theAhmedabad Chapter of Computer Society of India.

49

ENGINEERING SERVICES

Mr. B. L. Panchal

Bangalore

Ahmedabad

Mr. R. D. Shah

Bombay

LIBRARY

Mrs. R. R. BharuchaDelhi

Fifth Asian Regional Conference on Soil Mechanics andFoundation Engineering during 19-22 December, 1975.56th Annual Convention of Institution of Engineers(India), during 16-20 January, 1976.

Seminar on "Development in construction industry"during 6-8 December 1975.

Seminar on Towards the Evaluation of Information Sys-tem for National Development, 8-9 December, 1975.

50

VISITS TO UNIVERSITIES, RESEARCH ORGANISATIONS ANDTALKS GIVEN THERE IN 1975-76

SOLAR AND PLANETARY PHYSICS

Prof. R. G. RastogiPeru

Bedford, USA

Texas, USA

Boulder, USA

Dr. J. S. ShirksPoona

Dr. B. H. SubbarayaFrance

West Germany

USSR

Mr. R. N. MisraUSSR

INFRARED ASTRONOMYProf. P. V. KulkarniVerriers, FranceMarseille, France

Dr. J. N. DesaiVerrieres, France

Verriers, France

Jicamarca Radio Observatory, 28th Aug.-3 Sept., 1975.Huancayo Astrophysical Observatory, 22-27 Aug. 1975.Air Force Cambridge Research Laboratory to discussprogrammes of Beacon Satellite studies and gave seminarthere. 6-13 Sept., 1975.Goddard Space Flight Centre for one week.NASA for one week to discuss the current interest inATS-6 Beacon studies. 15-18 Sept.University of Texas at Dallas, the Institute of SpaceStudies to discuss the coordination of 0G0-6 datawith ground based ionospheric data from different labo-ratories round the world. 20-28 Sept.NOAA Laboratories to work with scientists on problemsconnected with equatorial aeronomy. Gave a series ofseminars highlighting contributions of PRL towardsequatorial aeronomy. 29 Sept.-4 Nov., 1975.

Poona University.Gave lecture on Space Research Activities at PRL.

Several CNES scientific laboratories in and around Parisas well as the CNES Space Technology Centre at Tolousefor a period of one week in August 1975 under theISRO-CNES exchange programme.Satellite Electronic Centre, Mobile Rocket Base as wellas the Institute for Atmospheric Physics of DFVIR, WestGermany at Oberpfaffenhofen for a period of one weekin Sept. 1975.Soviet Cosmodrome to participate in the prelaunch prepa-rations and checkout procedures of the AryabhataSatellite during April 1975.

Soviet Cosmodrome to participate in the prelaunchpreparations and checkout procedures of the AryabhataSatellite during April 1975.

Meudon Observatory, Haute-Provence Observatory.LAS Marseille.To understand the Infrared Astronomy work done atthese places. The program was for one week.

Laboratorie Aime Cotton and Service de Aeronomy underISRO-CNES program to study Fourier TransformSpectroscopy for three months.Service d' Aeronomie to study detection techniques forthe far infrared under the ISRO-CNES collaboration forone month.

51 52

THEORETICAL PHYSICS(i) NUCLEAR THEORY

Prof. S. P. PandyaGauhatiDibrugarhBangaloreMadrasBombay

Dr. J. C. ParikhOrsay, France

Oslo, Norway

Copenhagen, Denmark

Frankfurt, W. Germany

New York, USA

Rochester, U.S.A.

Dr. S. K. SharmaTrieste, Italy

Bonn, W. Germany

Cologne, W. Germany

(ii) PLASMA PHYSICS

Prof. B. ButiDelhi

Bombay

Dr. A. C. DasPilani

Dr. A. R. PrasannaMadras

Dr. A. SenBombay

University of Gauhati.University of Dibrugarh.

University of Bangalore.University of Madras.IIT, Feb. 11-12, 1976. Delivered two seminars on"Deformed configuration-mixing calculations for nuclearstructure.

Institute of Nuclear Physics, May-June 1975.Delivered 10 lectures on Group Symmetries.Physics Department, University of Oslo, April 1975.Study of Slater determinants wave functions in Nuclei.Neils Bohr Institute, April 1975.Delivered a lecture on Statistical and Group TheoreticMethods in Nuclear Physics.Institute of Theoretical Physics, July 1975.Delivered a lecture on Widths of determinantal statesand norms of interactions.Centre for Theoretical Studies, M.I.T. October 1975.Gave a talk on "Symmetries and Statistics."Physics Department, University of Rochester, November1975.Gave a talk on "Mass formulae and mass relationships."

International Centre for Theoretical Physics, January1975 to July 1975.Gave a seminar on "Hartree-Fock Bogolyubov calcula-tions in 2p-1f shell nuclei"Institute of Nuclear Physics, University of Bonn, July1975 - January 1976.Institute for Theoretical Physics, University of Cologne.Gave a seminar on "Some Microscopic Calculations forCeranium and Selenium Isotopes."

Seminar at IIT on Nov. 6, 1975.

Course of lectures at IIG, Feb. 1976.

Lectures on plasma instabilities in ionosphere andcommunication at Summer School held at B.I.T.S., June22-29, 1975.

Two lectures at Matscience, Oct. 1975.

BARC (Laser Group) March 29, 1976.

52

Professor R. K. VarmaBombay

Calcutta

Bhubaneswar

Winter School on High Energy Astrophysics.Gave a talk on "Interaction of a neutral gas with amoving magnetised plasma."Saha Institute of Nuclear Physics.Gave the following seminars :a) "Interaction of a neutral gas with a moving magne-

tized plasma."b) "Experimental Plasma Physics Programme at PRL."c) A series of four talks on "Statistical Mechanics

of Solitons and Turbulence."Institute of Physics. Gave lectures :

a) Deterministic Model Equations of Motion for Quan-tum Mechanics.

b) The Fermi-Pesta-Ulam problem and Solitons.

LABORATORY PLASMA AND ASTROPHYSICS

Dr. Y. C. SaxenaStockholm, Sweden

Roskilde, Denmark

ARCHAEOLOGY-HYDROLOGY

Dr. D. P. AgrawalLucknow

PoonaVaranasiJaipurNew Delhi

The Royal Institute of Technology, Department of PlasmaPhysics, during 23rd August, 1975 to 7th September, 1975.Department of Physics, Danish Atomic Energy Commis-sion, Research Establishment RISO, during 7th Sep-tember 1975 to 9th September, 1975.

Delivered the 23rd Sir Albert Charles Seward MemorialLecture, BSIP, Lucknow. The topic was : "Reconstructingthe past climate and environment."

Decan College. Delivered an invited lecture.Banaras Hindu University. Delivered invited lectures.Rajasthan University. Delivered invited lectures.School of Archaeology. Delivered invited lectures.

I 53

LECTURES DELIVERED BY VISITING SCIENTISTS FROM 1-4-75 to 31-3-76

Date Name and Address Topic

8 April

10 April

18 June

24

25

26

2

10

23

5

6

7

13

June

June

June

July

July

July

August

August

August

August

-do -

16

28

5

11

22

10

August

August

September

September

September

November

Prof. Cyril Ponnamperuma,University of Maryland, USA.

Dr. D. K. Madyozhin,Institute of Applied Maths.,USSR Academy of Sciences, Moscow.Dr. P. S. Dutta,NT, Kanpur.

Mr. N. T. Amritmahal,Audio Visual Dept., USIS.

Prof. U. R. Rao,ISRO/ISSP, Bangalore.Prof. S. P. Khare,Meerut University.

Dr. K. Shivanandan,Naval Research Lab., Washington.Mr. Lalit A. Patel,IIT, Delhi.Prof. I. Alexeff,University of Tennessee, USA.Dr. N. Sundaraman,Climatic Impact AssessmentProgram, Washington, USA.Prof. I. Alexeff,University of Tennessee, USA.

Dr. Fedynski,Hydro Meteorological Services, USSR.Prof. E. C. G. Sundarshan,University of Texas at Austin, USA.Prof. I. Alexeff,University of Tennessee, USA.

-do -Prof. P. Koteswaram,Andhra University, Waltair.Dr. B. M. Reddy,NPL, New Delhi.

Dr. P. A. Arriens,Australian National University,CanberraProf. A. K. Pradhan,University College, London.Dr. Ramanathan,Meteorological Dept.

The origin of life in the universe.

Recent developments in gravitational collapseand supernova outbursts.

Estimation of ground water recharge bytracing the movement of tritium in unsatu-rated zone.

What we have learned from the Moon -Harrison Schmit and Age of man in space.

Aryabhata.

Atomic and molecular collisions process.

Infrared Astronomy.

Photonic interferometry.

Current status of nuclear fusion.

Stratospheric Pollution by Supersonic Aircraft.

Creation of Highly Stripped loans in Plasmas.

Meteorological Investigation in Plasmas.

Measurement and Causality.

A simple approach to ion acoustic waves.

Anti Solitons.

The Indian monsoon circulation and MONEX.

Polar wind.

Conjugate History of India, Australia andAntarctica.

Close coupling method for scattering ofelectrons by atoms and positive ions.Numerical Weather Forecasting.

54

Date Name and Address Topic

28 November Dr. U. B. Sheorey,Inst. of Opthalmology,University of London, England.

29 November

23 December

26 December

30 December

2 January '76

3 January

5 January

-do-

6 January

16, 17 & 19January

27 January

2 February

4 February

5 March

8 March

Dr. S. D. Verma,Phys. Dept. Gujarat University,Ahmedabad.

Prof. J. B. French,Dept. of Phys. and Astronomy,Univ. of Rochester.

-do -Mr. Shiv Kumar,Univ. of Texas at Dallas, USA.Prof. G. Burbidge,Univ. of California, USA.

Mr. Shiv Kumar,Univ. of Texas at Dallas, USA.Prof. Joachim Herrmann,Central Inst. of Archaeology,Academy of Sciences, GDR.Prof. Edward Gerjuoy,Univ. of Pittsburgh,Pennsylvania, USA.

Prof. H. P. Noyes,Stanford Linear Accelerator Centre,Stanford Univ., Calif.

Dr. M. V. R. K. Murty,BARC, Bombay.Dr. Danilov,Hydrometeorological Services, USSR.

Dr. (Mrs.) Sinha,Univ. of Pittsburgh, Pennsylvania,USA.Dr. Vikram Dalai,Princeton Univ., USA.Dr. R. R. Daniel,TIFR, Bombay.Dr. V. V. Wagle,C/6 Shanti Nagar, Mogal Lane,Mahim, Bombay.

(i) development of a laser interferometer forevoked potential tests in eyes with opacities;(ii) fundus reflection densitometry for theassessment of retinal pigment; (iii) laserlight scattering (quasi-elastic) for blood flowmeasurements from within individual retinalvessels; and (iv) on-line signal analysis ofbio-electric signals.Age of Cosmic Rays.

Spectral Fluctuations

Statistical aspects of nuclear structure.

Atmospheric explorer concept and resufts-l.

Present state of research in quasi stellarobjects.

Atmospheric explorer - concept and results-ll

Use of Natural Sciences in ArchaeologicalResearch Work in the German DemocraticRepublic.Few charged particle problem in atomicphysics.

Relativistic three-body equations.

Optical Fabrication and Testing. (3 talks).

New concepts in D-region chemistry.

Resonant charge transfer at low energies.

Recent development in solar energy.

The TIFR investigations on cosmic rayelectrons and related astrophysics.

Determination of electron drift velocity andimpedance of gas discharge plasma.

5 5