AaWyem / 30/SiS

FINAL REPORT FOR MDAC SOLARCOSMIC RAY EXPERIMENT ON OGO-6

A. J. Masley

Space Sciences DepartmentMcDonnell Douglas Astronautics CompanyHuntington Beach, California 92647

January 1973Final Report for Period March 1966 - January 1973

Prepared for

GODDARD SPACE FLIGHT CENTER AGreenbelt, Maryland 20771 . '"

( N AS ~ ~ ~ SO AR-T~1 5 --csoA CoSM A -EXPERIMENT ON OGO-6 Final ReportI fa. NMar.3-16i1966 - Jan. 1973 (McDonnell-DouqlasAstronautics Co.) 7 p HC $4.56 as

CSCL 0 G3/53693UnclasCSCL 03B G3/29539

41

&-is RC . so

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.MDC G4351

4. Title and Subtitle 5. Report DateFinal Report for MDAC Solar Cosmic Ray January 1973Experiment on OGO-6 6. Performing Organization Code

7. Author(s) 8. Performing Organization Report No.A. J. Masley

9. Performing Organization Name and Address 10. Work Unit No.McDonnell Douglas Astronautics Company5 301 'Bol s a Ave nue~~~~~~~~5301 Bolsa Avenue 1 ~11. Contract or Grant No.Huntington Beach, California 92647 NAS5-9324

12. Sponsoring Agency Name and Address 13 Typ c4,Report and Period CoveredGoddard Space Flight Center mnaf epor

Mar 196 6- Jan 1973Greenbelt, Maryland 20771 14. Sponsoring Agency CodeTechnical Monitor: Mr. K. Meese

15. Supplementary Notes

16. Abstract

This report describes the instrumentation of the MDAC OGO-6experiment and discusses the results of data obtained during thesatellite lifetime from launch on June 5, 1969 through September 1970.

17. Key Words (Suggested by Author(s) 18. Distribution StatementSolar Cosmic RaysOGO-6Charged Particles

19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price"Unclassified Unclassified

For saleby the National Technical InformationService, Springfield, Virginia 22151

i

JI

PREFACE

The objective of this program was to obtain detailed measurements

of the intensities of protons, electrons, and alpha particles from a

polar orbiting satellite and to study the measurements in order to

better understand the methods of charged-particle entry into the

magnetosphere and their propagation into the low-altitude polar

regions. The work involved design, construction, testing, calibra-

tion, and delivery of a flight unit and a prototype instrument to

Goddard Space Flight Center for payload integration, as well as

computer data reduction and analysis of the data tapes provided by

the contractor. Several conclusions drawn from this study of the

data are presented in the report.

ii

TABLE OF CONTENTS

I Introduction 1

II Instrumentation 2

III Data Processing 5

IV Scientific Investigation 12

V Papers and Presentations 37

VI Acknowledgments 39

iii

FIGURES

2-1 MDAC OGO-6 Experiment 2

2-2 Expanded View of Experiment 4

3-1 Polar Pass Profile 8

3-2 Proton Energy Spectrum 9

3-3 Alpha Particle Energy Spectrum 9

3-4 Event Profile 11

4-1 Integrated Solar Proton Intensity 12

4-2 Solar Cosmic Ray Event Distribution 14

4-3 OGO-6 7 June 69 15

4-4 25 September 1969 Solar Cosmic Ray Event 16

4-5 25-30 September 1969 Intensity Profiles 17

4-6 25 September 1969 Differential EnergySpectra 17

4-7 27-28 September 1969 Differential EnergySpectra 18

4-8 29 September 1969 Differential EnergySpectra 19

4-9 2 November 1969 Event 20

4-10 2 November 1969 Regression Plot 21

4-11 2 November 1969 South Polar Pass 21

4-12 2 November 1969 North 22

4-13 3 November 1969 North 23

iv

4-14 2 November 1969 Solar Cosmic Ray Event 23

4-15 OGO-6 Observations and Theoretical CutoffRe sults 25

4-16 Magnetic Field Configuration 26

4-17 2 November 1969 South Spectra 27

4-18 Equatorial Projections of ParticleTrajectories 29

4-19 OGO-6 Trajectories Over South Polar Region 29

4-20 Calculated and Measured Absorption,2 November 1969 30

4-21 23 July 1970 Solar Particle Event 32

4-22 Proton/Alpha 5-21 MeV/Nucleon 33

4-23 Proton/Alpha (16-35 MeV) 34

4-24 Proton/Alpha 8-16 MeV/Q 35

V

TABLES

2-1 Channel Energy Boundaries 3

4-1 Solar Cosmic Ray Events 13

4-2 Calculated 5 MeV Proton Cutoffs 28

vi

I. INTRODUCTION

This document is the final report on the low energy solar cosmic ray

experiment developed by McDonnell Douglas Astronautics Company (MDAC)

and orbited on the NASA OGO-6 satellite. The complete program included

the design, construction, testing, calibration, and delivery of the flight and

prototype units as well as data reduction and analysis. The MDAC experiment

was utilized from launch on June 5, 1969 until the loss of satellite programming

signals in September 1970. The instrument operated flawlessly during this

entire time, measuring the intensities of protons, electrons, and alpha

particles during some 20 distinct solar cosmic ray particle increases.

Section II of this report briefly describes the instrument used to make the

particle-intensity measurements. For more detail see the Instrument

Report submitted as part of this contract in March 1968 or see IEEE Trans-

actions on Nuclear Science, Vol. NS-15, 238 (1968). Section III describes

the data-processing procedure and Section IV discusses the scientific

investigation.

The following MDAC personnel were involved in this program

A. J. Masley Principal Investigator

P. R. Satterblom Co-Investigator

M. H. Wolpert Electronic Engineering

D. W. Burtis Electronic Engineering

K. A. Pfitzer Computer Programming

R. B. Atkinson Computer Programming

1

II . I N S T R U M E N T A T I O N

The OGO-6 MDAC fl ight un i t i s shown in F i g u r e 2 - 1 . T h i s s e l f - c o n t a i n e d

p a c k a g e wi th the a t t a c h e d c h a r g e d - p a r t i c l e t e l e s c o p e w a s m o u n t e d on the

i n s i d e of the -Z d o o r of the s p a c e c r a f t wi th the t e l e s c o p e p r o t r u d i n g t h r o u g h

an a p e r t u r e in the d o o r . T h i s s ide w a s o r i e n t e d by the s p a c e c r a f t a t t i tude

c o n t r o l s y s t e m to po in t r a d i a l l y away f r o m the E a r t h . The d e t e c t o r s y s t e m

i s a c h a r g e d p a r t i c l e t e l e s c o p e , c o m p o s e d of two s i l i c o n d o u b l e - d i f f u s e d

c i r c u l a r d e t e c t o r s m o u n t e d c o a x i a l l y wi th a s e p a r a t i o n of 36 m m giving a cone

h a l f - a n g l e of 28 deg . By m e a s u r i n g a p a r t i c l e ' s e n e r g y l o s s in two d e t e c t o r s ,

i t s to ta l k i n e t i c e n e r g y and i t s m a s s c a n be d e t e r m i n e d . The e x p e r i m e n t

a n a l y z e d p r o t o n s f r o m 5. 3 to 78 MeV in 14 c h a n n e l s and a lpha p a r t i c l e s f r o m

17. 5 to 84 MeV in n ine c h a n n e l s . Add i t i ona l l y , a m i n i m u m ion i z ing c h a n n e l

m e a s u r e d the i n t e n s i t y of e l e c t r o n s g r e a t e r than 270 keV a long wi th p r o t o n s

g r e a t e r t han 78 MeV. T h e s e c h a n n e l s and t h e i r e n e r g y b o u n d a r i e s a r e l i s t e d

in T a b l e 2 - 1 . T h e t e l e s c o p e g e o m e t r y f a c t o r i s 0 . 4 9 9 c m s t e r .

The q u a n t i t i e s of c h a r g e l i b e r a t e d in e a c h d e t e c t o r w e r e c o n v e r t e d to vo l t age

p u l s e s by the a m p l i f i e r s . T h e s e v o l t a g e p u l s e s w e r e a m p l i t u d e a n a l y z e d by

CR11 POLAROID

Figure 2-1. MDAC OGO-6 Experiment

2

Table 2 -1

CHANNEL ENERGY BOUNDARIES

Kinetic Energy(MeV)

5. 3

6. 0

8.2

11.0

12.7

16. 0

20.7

24. 5

29

35

41.5

49

59

70

17.5

20.2

21.8

26

34.2

46

53

62

72

Protonsto 6.0

to 8.2

to 10.5

to 12.7

to 16.0

to 20. 7

to 24.5

to 29

to 35

to 41.5

to 49

to 59

to 70

to 78

Alpha particlesto 20.0

to 21.8

to 26

to 34.2

to 46

to 53

to 62

to 72

to 84

Protons 5 -78 MeV

Alpha particles 20.2 - 125 MeV

Protons greater than 78 MeV

Electrons greater than 270 keV

Integral channels

a combination of threshold circuits and a clock-type pulse height analyzer.

Ten shifting accumulators were used to count the pulses in the data channels

using a multiplexing technique which gave a 31 percent on-time for each

3

ChannelNo.

P1

P2

P3

P4

P5

P6

P7

P8

P9

P10l

Pll

P12

P13

P14

Al

A2

A3

A4

A5

A6

A7

A8

A9

11

13

c h a n n e l . Of the c o m p l e t e s e t of 30 da ta c h a n n e l s , e a c h w a s s a m p l e d for

0 .270 s ec e v e r y 0 . 8 6 4 s e c . An e l e c t r o n i c in- f l igh t c a l i b r a t i o n s y s t e m

checked the vo l t age l e v e l of e a c h t h r e s h o l d c i r c u i t a s we l l a s the p u l s e he igh t

a n a l y z e r e v e r y 160 m i n . The e x p e r i m e n t we ighed 2 . 6 2 kg, r e q u i r e d 2 . 2W 3

of s p a c e c r a f t power , and had d i m e n s i o n s of 20 x 20 x 10 c m .

An expanded view of the i n s t r u m e n t is shown in F i g u r e 2 - 2 . The e l e c t r o n i c

c o m p o n e n t s a r e h o u s e d in the t h r e e t r a y s . The p a r t i c l e t e l e s c o p e is a t t a c h e d

to the b o t t o m of the m i d d l e t r a y and ex t ends t h r o u g h the uppe r t r a y wi th the

c o l l i m a t o r (not shown) a t t a c h e d to the t h r e a d e d t e l e s c o p e h o u s i n g . The

d e t e c t o r a m p l i f i e r s and t h r e s h o l d c i r c u i t s a r e m o u n t e d c l o s e t o the t e l e s c o p e

in the m i d d l e t r a y . The left t r a y h o u s e s the t e n a c c u m u l a t o r s and a s s o c i a t e d

p r o g r a m m i n g c i r c u i t r y . The r i gh t t r a y c o n t a i n s the power c o n v e r t e r , the

logic c o n t r o l c i r c u i t r y , and a l l the s p a c e c r a f t i n t e r f a c e d e v i c e s . E a c h t r a y

c o n s i s t s of a m a g n e s i u m hous ing wi th a bonded m o t h e r b o a r d . D i s c r e t e

c o m p o n e n t s a r e moun ted on c o r d w o o d m o d u l e s and i n t e r c o n n e c t e d by we lded

n icke l r i b b o n .

CR11 SM499402

SOLAR COSMIC RAY EXPERIMENT OGO-F F-19

Figure 2-2. Expanded View of Experiment

4

III. DATA PROCESSING

A, Quick-Look Data

The OGO-6 data were processed in three distinct stages. First, quick-look

data were prepared from ROSMAN and ULASKA data tape dumps and real-

time passes by the data reduction group at Goddard Space Flight Center

(GSFC). The data were presented in the form of printouts and print-plots as

specified by the experimenter, and this service was provided for two weeks

following the spacecraft launch. It was especially important to receive these

data because of a solar particle event that occurred on June 7, 1969, only

53 hours after the spacecraft launch. The data were presented in a paper to

the 11th International Conference on Cosmic Rays at Budapest, Hungary, in

August 1969.

B. Preliminary Processing

Since data tapes were provided to the experimenters several months before

attitude-orbit tapes were ready, a preliminary data-processing program was

written to present experiment data as a function of universal time. Selected

experiment data channels were summed together so that eight proton channels,

two alpha particle channels, one integral channel, and one experiment tempera-

ture were plotted on three sheets for the period of one orbit. The program

incorporated features which filtered out noisy data, monitored data quality,

and adjusted data summation time intervals depending on the count accumula-

tion in a selected channel. The computer used was an XDS-930 with a

Calcomp 835 microfilm plotter on-line. Details of this program were given

in the Prime Data Analysis Plan which was submitted to GSFC to meet a

contractual requirement.

Early data tapes contained many data records which could not be processed

due to time errors. Time skips and backups of both short and long duration

in a record were not anticipated and could not be handled by the program. At

the suggestion of the GSFC OGO data center, it was decided not to alter the

preliminary processing program to handle time backups; however, a time

skip method was developed. The GSFC OGO data tape line was later improved

and a restart made on experimenter tapes on February 16, 1970. Since then,

time skips or backups in a data record have not occurred.

5

C. Final Data Processing

Final data reduction was performed in two steps utilizing an XDS-930 computer.

The first step merged experimenter data tapes with the attitude-orbit tapes

and produced a compact MERGE tape. During this process, data flags and

data quality were checked and data from the in-flight calibration sequence

were removed prior to writing the output MERGE tape. The data were sorted

and sequenced monotonically in time and all duplicated data deleted. During

solar quiet periods, many of the data readouts were zero; therefore, a zero

suppression technique was used which shortened the output tape length by more

than a factor of 10. In this way, a full MERGE tape could contain six or seven

days of experiment data, including data from both the experiment and attitude-

orbit tapes. The attitude-orbit data were also filtered and sequenced (periodic

time overlaps and skips appeared on these attitude-orbit tapes). The data

were converted from UNIVAC or IBM floating-point format to a scaled integer

format. The number of bits retained to the right of the binary point varied

and was determined by the accuracy requirement for further analysis. Thirty

attitude-orbit information words were written on the MERGE tape. The

MERGE tape, containing binary scaled attitude-orbit data and zero suppressed

experiment data, then constituted the working tape for all subsequent analysis.

The second step of the data analysis consisted of generating microfilm plots

and printouts of the desired data. Two basic programs were written, both for

the XDS-930 computer with an on-line Calcomp 835 microfilm plotter. The

first program generated plots and listings of individual polar passes while the

second program was used for long duration profiles of a solar event. Self-

scaling linear and logarithmic axis generation subroutines as well as self-

scaling linear time axis generation subroutines were developed for use in both

of these programs.

The program for plotting polar pass data, OGOPLOT, can calculate time

averages of the data from 10 sec up to several minutes. A complete polar

pass, determined by selected values of invariant latitude, could be plotted or

any portion of the polar cap could be expanded into a separate plot. Up to four

data channels arranged in a specific order could be displayed on a single frame.

6

As many plots as requested to cover all channels or any subset of channels

were available in a single pass through the data. This program also plotted

the log-log energy spectra of protons and alpha particles averaged over a

time interval from 10 sec to several minutes for any specified region of the

polar cap.

Figure 3-1 shows an example of a polar pass profile. The information in the

upper right of the figure indicates that the plot is for protons, a northern

polar pass, on March 24, 1970. The four data channels plotted are 5. 3 to

6. 1 MeV, 6. 1 to 8.2 MeV, 8.2 to 11.0 MeV, and 11.0 to 12. 7 MeV. The

abscissa is labeled in both time and space coordinates. The large numbers

at the top of the column are the universal times corresponding to the adjacent

vertical bar of the plot. Below the time are the other coordinates which apply

to the sameuniversal time. The other coordinates are local time, magnetic

local time, the McIlwain L parameter, magnetic latitude, invariant latitude,

geographic latitude and geographic longitude of the subsatellite point, and the

satellite altitude. The ordinate is in units of differential intensity.

Figure 3-2 shows an energy spectrum of protons taken during this same polar

pass. The plot is labeled for protons during a northern polar pass on

March 24, 1970. The univeral time at the midpoint of the accumulation period

is given. Below this is the same coordinate values occurring for that time as

are shown in Figure 3-1. DT shows that the accumulation interval was

2. 00 min. The ordinate of the plot is in differential intensity units. The

crosses that indicate the data points show the energy width of the channel

(the horizontal line) and the statistical error in the differential intensity

(the vertical line). The horizontal axis gives the kinetic energy of the particle.

Figure 3-3 shows an alpha-particle energy spectrum for data during the

November 2, 1969 event.

The second plotting program, OGOPROF, permitted a time history of an

event or sequence of events to be generated for any given channel or set of

channels. The plot time duration could be chosen from one day to several

months.

7

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Figure 3-2. Proton Energy Spectrum

l d

0-1 0

N I

TL10

10U

Z -2

1 0-0 100

T ( MEV)

Figure 3-3. Alpha Particle Energy Spectrum

9

CR11PROTNORTH24 MRR 70lltl 0 UT1054 LT1458 HLTL 33.52MLRT 78.84ILRT 80.05GLRT 81.98LONG 357.57ARLT 842.87

OT 2.00

00

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Each data point consisted of the average over one polar pass of the data from

one channel or group of channels, as determined by a selected invariant

latitude. North and South polar passes were indicated by different symbols.

The program was also capable of plotting the sum of any arbitrary set of

channels or the ratio of the sums of two sets of channels.

Figure 3-4 shows an example of a profile plot for the interval from

March 23, 1970 through April 1, 1970. Two channels of data are plotted,

P1 being protons from 5. 3 to 6.0 MeV and P6 being protons from 16.0 to

20. 7 MeV. In the upper left of the figure, these two channels are labeled,

indicating that the ordinate is in differential intensity units. Each channel

has a different symbol for northern and southern polar passes. The factor

stated for each channel is the number that converts the average number of

counts per channel readout to a differential intensity. The program version

is dated so that it is possible to document the current state of the program,

e. g., the channel factors used. MINLAT is the minimum absolute value of

the invariant latitude for data to be included in the plot.

During the life of the OGO-6 satellite there were 20 time intervals totaling

146 days which had higher than background intensities of charged particles

as measured by this instrument. The data from these periods were compacted

onto 29 MERGE tapes and underwent subsequent analysis. Event profiles from

the OGOPROF program were plotted for these 20 intervals. Some of the

profiles were done in several formats due to the length of the interval or to

some peculiar feature of the data. The profile of the ratio of the proton and

alpha particle intensities was plotted for many combinations of proton and alpha

particle energies for the ten events with highest particle intensity. For nine

of the highest intensity events, the OGOPLOT program was used to obtain

individual polar-pass intensity profiles and proton and alpha particle spectra

during most of the event. These types of plots were not made routinely due to

the large number of plots which were generated. For even a two minute

averaging time (a ten sec average can be statistically significant during the

most intense periods of several events), 320 plots per day of data were pro-

duced. The total number of plots produced by these two programs is on the

order of 1.5 x 104.order of 1. 5 x 10

10

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IV. SCIENTIFIC INVESTIGATION

This section discusses in detail the solar cosmic ray events that occurred

during the life of the OGO-6 satellite. Also included are the theoretical cutoff

calculations with which the data can be compared. Comparisons are also

made with data from the MDAC riometer program. A summary discusses the

extent to which the proposal goals were achieved.

A. Event Coverage by OGO-6 During Solar Maximum

The MDAC experiment functioned perfectly from "turn on," on June 6, 1969,

up to September 1970 when the spacecraft digital data assembly malfunctioned.

This period was during the maximum of Sunspot Cycle 20, as illustrated in

Figure 4-1. The experiment was on over 99 percent of the time and excellent

data were obtained for all 23 events which occurred (Table 4-1). The maxi-

mum intensities of 5 to 21 MeV and 10 to 80 MeV (essentially >10 MeV) are

given in Table 4-1 as well as the maximum 30 MHz riometer absorption.

Figure 4-2 shows the solar particle event distributions from 1962 through

1971. The crosshatched boxes illustrate how the OGO-6 event coverage fits

into the nine-year distribution.

CR11

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Figure 4-1. Integrated Solar Proton Intensity

12

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CR11

SOLAR MAXIMUMNOVEMBER 1968

4 .7dB 1.

12.5

76-~~~~

140- _ 0 4

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of ~~~~80 ~SOLAR MINIMUM 11.0 . 1.

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~ ~~~~~~~~~~~~~~ ,, 1 .320 0.2 2.0 216 0.

0. .602d .88 1.9. 0.7 1.47. 1.

1962 1963 1964 1965 1966 1967 1968 1969 1970 1971

Figure 4-2. Solar Cosmic Ray Event Distribution

B. Discussion of Specific Events

June 7 Event (Papers 2, 4 and 8)

Figure 4-3 shows the June 7 event as observed by 30 MHz riometers at

Shepherd Bay and McMurdo Sound and by the MDAC experiment. For about

five hours after the onset near 2000 UT on June 7, significant anisotropies

were observed as the satellite crossed a given polar cap. Variations in count

rate up to a factor of ten were observed. From onset to the second maximum

at 1600 UT on June 8, no significant asymmetry was observed between the

North and South polar regions. From this time on, a larger intensity was

observed over the North polar cap. The northern excess was about 50 percent

for several hours, after which it was reduced to 20 percent for the next two

days. The decrease in the southern hemisphere is not a low-energy cutoff

effect but a depression of the entire spectrum. A regression plot of the rio-

meter and OGO-6 data indicates good agreement with A(db) = KI1

/2

for both

the increasing and decreasing phases.

14

CR11

_ 1{v / (JU MHZ)SHEPHERD BAY . / McMURDO SOUNDSUN ALWAYS UP 1.2 MISSING (30 MHz)

~ ./DATA 'lliI,/McMURDO SOUNDSUN ALWAYS DOWN c

0.4 0 ,, 0

0 !:112 1 00 12 00 12 00 12 00°° 12 "' 0 2

6-8 . 6-9 -< 6-10;6-11- 6-12

UNIVERSAL TIME

102

lo 101 _ NORTH

X~,~~~~ . * SOUTH

5-11 MeV PROTONS

10-1 7~~~~~~~~X 100

10'1 -.. .

00 12 00 12 00 12 00 12 00 12 00 12 00

I---- 6-7 --- 6-8 -- 6-9 -'1, 6-10 -I. 6-11 1-*- 6-12 - 1

UNIVERSAL TIME

Figure 4-3. OGO-6 7 June 69

15

September 25 and 28, 1969 Events (Papers 7, 8, 14, 17, and 18)

Figure 4-4 shows the OGO-6 5.3 to 6. 1 MeV proton and McMurdo riometer

profiles during the September 25 and 28, 1969 events. Figure 4-5 shows two

low energy and the greater than 80-MeV profiles. A 2N flare at N14 W14 was

reported to begin at 0700 UT on September 25. At 0759 UT, protons were

observed only in the >80 MeV channelduring a southern polar pass. Figure 4-6

shows the classical buildup of the spectrum on succeeding passes. The high-

energy particles arrived first, with low energies arriving later due to velocity

dispersion.

On September 27 a 3B flare was observed beginning at 0347 UT and located

N09 E02. The major increase due to this flare occurred with the SC at

2125 UT. This event with particles confined behind the shock wave demon-

strated very little velocity dispersion as particles at all energies were present

from the beginning, as shown in Figure 4-7.

100

10a,

a,0>

(Nn

0

E 1.0(/3Z

i-0To0.

0.1

- ! 2.0

-- O-o 0a:

0- 1.0co

0.01 -12

27 SEPDAYS

Figure 4-4. 25 Sept 1969 Solar Cosmic Ray Event

16

E

4,

E

z0I-0C.

100- A SC 0453 UT- _ 5.3-6.1 MeV PROTONS/Cm2Sec Ster MeV I\ A- ~ 11-16 MeV PROTONS/Cm2Sec Ster MeV I I \

_ __> 80 MeV PROTONS/Cm2Sec Star (+10) e ;

10.0 -A\~~~ ̂ _ ~~~~MAG · j 'o

M ~~~~~~~STORM-225 UT| ~ / vI

,o ,~ "~, / / A ̂

0.1 __- X,, ,,, Q .........~.. ......... ~,..._,.......,.. .1 #,,-.._ ....

0.01An/

00 1Z UU Z o00 12 00 12 00 12 00 121 25 SEP I 26SEP I 27SEP I 28 SEP I 29SEP I 30 SEP

Figure 4-5. 25-30 September 1969 Intensity Profiles

>;=d,

EQwz0I-0

T (MeV)

Figure 4-6. 25 September 1969 Differential Energy Spectra

17

CR11

00I

CR11

CR11

28 SEPT0002 UTNORTH

E

z~~O 27 SEPT

O 2220 UTNORTH

0.1 I I I I 1 10 100

T (MeV)

Figure 4-7. 27-28 September 1969 Differential Energy Spectra

A final increase was observed coincident with the SC at 0453 UT on

September 29, as shown in Figure 4-8. The spectrum is identical before and

after the SC although the total intensity increased. The event began to decrease

rapidly about 16 hours after the SC similar to the April 1960 and May 23, 1967

events.

November 2, 1969 Event (Papers 3, 5, 6, 8, 9, 10, and 11)

The November 2 event was one of the largest observed since November 1960.

McMath Region 385 rotated into view November 20, 1969. This region

was one of the most complex visible spot groups of the current cycle. In

spite of this, it rotated out of view on November 1 without producing any major

particle event.

At 0943 UT on November 2, about one day behind the limb, a major flare

occurred. Importance 2 loops, a large 10-cm radio noise burst, and the most

energetic X-ray event of the year were observed.

18

CR11

E

-0

0.1 ]I1 10 100

T (MeV)

Figure 4-8. 29 September 1969 Differential Energy Spectra

Figure 4-9 shows OGO-6 and McMurdo Riometer observations. The southern

riometer saw the event start at about 1100 UT in daylight. The first OGO-6

observation was a northern polar pass at 1100 UT. Particles were observed

only in the greater than 80 MeV channel. On the following southern polar pass

at 1150 UT, particles over the entire energy range were present, with the

spectrum maximum at 35 MeV. The intensity of the greater than 80 MeV

protons increased abruptly, reaching its maximum at 1230 UT, the same time

as the riometer. The 5 to 80 MeV particles reached their maximum from

1400 to 2300 UT.

Figure 4-10 shows a regression plot of OGO-6 and riometer observations

showing excellent agreement with and confirming earlier theoretical work.

During the first southern polar pass, there were large variations across the

polar cap (Figure 4-11). The variation was nearly 100 to 1 for the 1330 UT,

November 2 southern pass. The distinctive stable features (sharp increase,

valley near the local noon side, and a double peak on the local midnight side)

19

CR11

100

ooo000 ~~~~~~2 NOVEMBER 1969 EVENT

b NORTHERN PASSJ J o SOUTHERN PASS

~A o^ A~t0^ ~OGO VI I

o 100° o A A

o ° o ciAo A A j 0 5.3 6.1MeV |0 Ah01

A < '00

A 0OA 4 ,A

10 ah A 0

d2 1 A 11 16 MeV 0

Lo o . a

' ° O i ,~I

0AA 4 4 ' oo0

%O ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~A

0°A1°6~~AA A 00. _ _ _____________________ _ ._ .___ __ _-~ AA ~ -~, _0A 0 A

Ao 0 AA A : A A

0 A, 0 0 CP 0

2-_.ATA DA T A~ AA

o

1 6 000 0 o A A 0

0 0

n0 2 0 1 A 1 00

A

A

A ~ ~ ~ ~ ~ ~ ~~~~~AA0 0 -~~~~~~~~~~~~~~~ boaoo

o 0

0.11 1 A 1 00 A

12igure ~~j 4-. .Nov e9 78 M.V E v

0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

0,0116 4~-

14 -] _ _

14~~~~~~~~~ SOLAR FLARES

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~2 A11-2-69 11-3-69 11-4-69 11-5-69 11-6-6 MC MURDO SOUND 30 MHz R1 9IMETER--6 I

(SUN UP 24 HOURS PER DAY)

r .6~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

MSSNG~ I SSI~NG DATA DATA M

(O 12 00 12 O0 12 00 12 00 12 00 12 00 12 00 12 00

I 11-2-69 j 113-369 1 11-4-69 I 11-5-69 I 11-6-69 I 11-7-69 [ 11 8-69 J 11.9-69 IUNIVERSAL T!ME

Figure 4-9. 2 November 1969 Event

20

102

z

To

C0~

m-10

Id.

QL_

NI

0

V)

0CO,

ZD

To

V)

10

I

10-1

1 10 102OGO-6#(11-78 MeV)

SOUTH PASSES

Figure 4-10. 2 November 1969 Regression Plot

P 5 3 6.1 | P

ICM 2 -SEC STER MeV] l1P 16245

: P > 80 ! [p ICM 2 -SEC STERI 1

UNIVFRSAL TIME

Figure 4-11. 2 November 1969 South Polar Pass

21

CR11

CR11

I

can be followed for about 12 hours to about 0000 UT, November 3, the variation

decreasing from 100 to 1 to about 6 to 1 over this period. The earliest

northern polar passes show some variation (about 25 to 1, see Figure 4-12),

but shortly thereafter the northern passes become more uniform(Figure 4-13).

Spectra at three points during the buildup of the event are shown in Figure 4-14,

which illustrates the energy dispersion or differential arrival time. The first

spectrum was taken during the first southern polar pass after the event started.

Since most lower energies had not yet arrived, the spectrum increased with

energy. During the next spectrum, at 1245 UT on the following northern pass,

the intensity increased and there was a broad maximum centered near 40 MeV.

Spectra near the peak of the event, which have a spectral shape typical of the

remainder of the event, indicate that low energies have arrived, causing the

intensity to decrease at higher energies.

In general, the event had a significant number of high energy particles, with

the middle energies, 50 to 300 MeV, relatively abundant. The lack of response

on neutron monitors indicates that there were essentially no particles of

CR11

102

101

lo,

100 -

10-1 -

P5.3-6.1 2 )p [CM 2 . SEC - STER -.MeV] 1 33 55 11.7P 16- 24.5 J FI I

o P> 80 } Op [CM 2 SEC - STER] 1 55.5 63.3 71.1o-2 1

I. I IL 15.8 7.1 4.2

I I IMLAT 77.9 70.4 62.9

I I

1236 1240 1244 1248 1252 UNIVERSAL TIME

Figure 4-12. 2 November 1969 North

22

1256 1300 1304

-- H-

CR11

I P53 6.11 5 p (CM2 -SEC STER .MeV]1

X P 16.24.5

c p > 80 } 4 'p [CM 2 - SEC .STER] 1

0502 0506 0510 0514 0518 0522 .6J'6

UNIVERSAL TIME

Figure 4-13. 3 November 1969 North

CR11

E3:

IuU

wto

NE

10 100E (MEV)

1000

Figure 4-14. 2 November 1969 Solar Cosmic Ray Event

23

greater than 500 MeV, although there were significant numbers greater than

80 MeV particles throughout the event.

Summary:

The event was due to activity one day behind the west limb of the sun.

The event was one of largest during cycle 20, having:

Maximum absorption: 14.5 dB

Maximum 5 to 80 MeV flux: 1,700/cm sec-ster, and

Integrated free space flux > 30 MeV - 3 x 10 7 /cm2

There were significant stable features in the polar profile lasting more than

12 hours.

C. Solar Particle Entry and Propagation (Papers 10, 12, 13, and 15)

The November 2, 1969 event, which was one of the largest during this solar

cycle, had quiet magnetic conditions throughout and high intensities of solar

protons, alpha particles, and electrons (Figure 4-9). The MDAC OGO-6 data

provide detailed information on the entry and propagation of solar particles

within the magnetosphere. The location of the first open field line at low

latitude on the noon side has been directly measured. This location was

monitored for 30 crossings during quiet magnetic conditions. The average

value of the invariant latitude was 76 deg for the northern hemisphere and

75 deg for the southern hemisphere. This represents good agreement with

the cusp region as measured by Heikkila.

The location of the first open field line is demonstrated by a sharp increase

in the intensity of 270 keV solar electrons (Figure 4-15, upper section). This

location is then used as an onboard reference for interpretation of proton and

alpha particle measurements.

Figure 4-16 is a model which illustrates conditions during this event. The

Earth was in a positive interplanetary magnetic sector. The northern hemi-

sphere, with possible field line merging along the tail, had a better connection

to the interplanetary field than the southern hemisphere. There was a large

variation in intensity across the southern polar cap for protons (Figures 4-15,

lower section) and alpha particles. The variation for 5 MeV protons in the

South decreased from a maximum of 285 to 1 to 1.4 to 1 over a 20-hour period.

24

CR11

- - ZZZ2- wN - ----

5.3 - 6.1 MeV PROTONSNO I

… _ -~~~ ,I 0i_ _ l ~~~~~ FIRST OPEN FIiELDiLINIE t = = =

~~~~~~CACA, T. CUT.F. -_-

L .3 - 6.~~~~~~~1MePRTNi

1326 _1328 1330 1332 1334 1336 1338 1340 1342 1344 13461300 1309 1319 1333 1361 1416 1453 1549 1700 1843 2006 2105 2145 2212 2231 2245 2256 2305 2312 2318 2323 23213.1 3.5 4.0 4.7 5.7 7.0 3.9 12.0 17.3 27.7 51.3 100.0100.0100.0100.048.2 24.4 14.7 SJ 7.0 6.3 4.1-53.6 -56.9 -60.1 -63.4 -66.6 -69.9 -73.1 -76.4 -79.7 -83.0 -86.3 -89.5 -87.1 -89.7 -80.4 -77.0 -73.6 -70.2 -66. 4-3.3 -59J -56.455.5 57.3 60.1 62.6 65.1 67.7 70.5 73.2 76.1 79.0 82.0 84.3 84.3 84.3 84.3 81.7 78.3 74.9 71.4 67.8 64.2 60.6

Figure 4-15. OGO-6 Observations and Theoretical Cutoff Results

25

1o3

w-j i020.

lO2

101uz

D 10°

I-

10-110-2

o,)

.4

UT

C.

10-

UTLTLMLATI LAT I

3II i

I

CR11BOUNDARYLAYER

TO SUN4

EARTH IN POSITIVE SECTOR

Figure 4-16. Magnetic Field Configuration

In the northern hemisphere, the variation ranged from 20 to 1 to 1.4 to 1 during

the same period. The two low-latitude, high-intensity regions shown in

Figure 4-15 are located below the predicted cutoff latitudes. The entry of

these particles is not understood and is the subject of current study by us.

Figure 4-17 shows spectra measured through this region in the southern

hemisphere. The persistent double hump suggests two entry mechanisms for

the particles.

Protons are nearly absent on the first open field line and the boundary of the

southern tail in a region where they are clearly allowed using theoretical cutoff

calculations. This suggests no diffusion across the boundary of the southern

tail region. The absence of protons and alpha particles is presumably due to

the anisotropic flux in interplanetary space, so that the particles cannot find

a path to get on to adjacent parallel field lines (same direction) near the tail

boundary.

This area of investigation is currently being developed into a PhD thesis by the

Principal Investigator. The thesis, which is being carried out with the

26

.mlI I p .I ...............I * . ='

I+

V --

Ill~~~~~~~~~~~~~~~~~~~I4- adi'- t F _ ..B iI -

.In

1+11 1,,, 1ll 1' I ' 1I, Y- ... ,, _

t.

l , , i;<,t

i~~~~~~

of~~~~

: I~~~~~~~~~~~~I

Cv~3t-,j

il0ll IllTl 11111 Xe-.0 O

A@W-bllS-33S-zW3/d

NI,9-

27

1C00

0V-

Cf-

8 V:E

I- w

10

00¢3.

01-

Q.

en

U,

0O3

0,(,00,.CD

E0

03tozaN. _

E0J

U-~

I

University of Melbourne, Australia, is based on OGO-6 observations and

related theoretical interpretations.

D. Theoretical Investigation of Solar Particle Entry and Propagation

within the Magnetosphere (Papers 10, 12, and 13).

Trajectories of solar particles were calculated to determine the cutoff latitude

and entry and propagation paths for specific cases. This was done using the

best field models available (Olson's tilted magnetosphere, a realistic tail

model, and the Fairfield-Mead empirical model). The results are shown in

Table 4-2. Over 200 trajectories were run for 5 MeV protons at noon and

midnight. Examples of these trajectories are shown in Figure 4-18. These

theoretical results were directly compared with measurements by the MDAC

experiment on OGO-6. The calculations give cutoffs 6 deg higher than

observed at midnight and 8 deg higher at noon. Recent unpublished work using

a new version of Olson's magnetospheric model with distributed currents have

reduced this disagreement to 2 or 3 deg.

E. OGO-6 and Riometer Studies (Papers 8, 19, 20, and 22)

OGO-6 and riometer data were used to study the November 2, 1969 event.

Proton energy spectra and proton/alpha particle ratios measured on OGO-6

at the times of passes close to the geomagnetic field line terminating at the

McMurdo Sound riometer station were used to calculate the 30 MHz riometer

absorption expected. The calculations were made by MDAC computer pro-

grams developed previously to understand riometer absorption. There were

five close passes when good data were obtained (Figure 4-19). Riometer

absorption was calculated due only to the protons, to protons and alpha

Table 4-2

CALCULATED 5 MeV PROTON CUTOFFS

Gallet al. Masley, Olson, and Pfitzer OGO-6

Investigator 1968 1971 Measurement

Tilt 0 0 +30 -30 -20 -20

Noon (Direct) 78 78 76 76 77 69I 69Noon (Tail) 70 74 .. ..

Midnight 68 69 69 70 69 -63

28

CR11

MAGNETOPAUSE y

/NOON /(MAGNETOPAUSE) I

MIDNIGHT(DRIFT)

- MIDNIGHT(TAIL)

-20

,NOON(TAIL)

Figure 4-18. Equatorial Projections of Particle Trajectories

CR11

120'

900

POLE

o, ( 1158-1159 UT 2 NCK ( 0247-0248 UT 3 NC

() 0428-0429 UT 3 NC

0750-0751 UT 3 NC

0931-0932 UT 3 NC

/ - I30° 0

Figure 4-19. OGO-6 Trajectories Over South Polar Region

29

particles, and to electrons. The contribution from alphas was always very

small.

The total absorption calculated and the actual 30 MHz absorption simultaneously

measured at McMurdo Sound are shown in Figure 4-20. Extremely good

agreement was obtained. A regression plot of McMurdo Sound 30 MHz rio-

meter versus the OGO-6 (11-78) MeVintensity illustrates good agreement

with the relationship A = K l/2, with K = -0. 3 established for earlier events.

F. Proton/Alpha Particle Studies (Papers 16 and 21)

OGO-6 measurements of the ratio of proton and alpha particle intensities at

5 to 21 MeV were analyzed in detail for the nine largest solar cosmic ray

events observed in the MDAC data. The ratio ranges from 25 to 1, 000 for

these events. The typical value is between 100 to 300 and varies by a factor

of 2 during an event. In most cases, the ratio was not dramatically affected

at the time of a sudden commencement, as has been discussed in earlier

literature. There were, however, two significant cases of SC effects on the

ratio. On September 27, 1969, the alpha particles appeared after the SC

12

11

10

z0a-ir

00co

CR11

00 06 12 18 00 06 12 18 00 06 12I1 2 NOV - | 3 NOV - - 4 NOV

UNIVERSAL TIME

Figure 4-20. Calculated and Measured Absorption, 2 November 1969

30

and on July 23, 1970, a sharp decrease in ratio was-observed at the time of

the second SC. As an example, the July 23, 1970 event is shown in

Figure 4-21.

The ratios were further analyzed in equal velocity, equal rigidity, and equal

energy/charge groups. The data are presented in these three groups for the

nine events in Figures 4-22 through 4-24. The analysis is proceeding to

attempt to understand the propagation effects from the sun so that particle

acceleration and storage can be studied. To investigate the importance of

the longitudinal effect, the data were organized with respect to the location at

1 AU of the solar magnetic field line from the flare or injection region.

In this manner, the events were divided into approaching or receding cases.

Preliminary results show that the ratio was similar and best organized for

receding events for equal rigidity intervals and the organization was improved

for approaching events for equal rigidity groups.

G. Summary

Excellent data were obtained for the 15 months of coverage provided by the

MDAC OGO-6 experiment. Data transmission was terminated in

September of 1970 due to a spacecraft malfunction, although the experiment

was still working perfectly. Data transmission was also terminated for

several other experiments due to this malfunction. Twenty-three events

were measured during this period near the peak in Solar Cycle 20.

All of the solar cosmic ray objectives in the original proposals (July 1964,

revised February 1965) were accomplished by the experiment. In some cases,

the investigation would preferably have been carried out more completely or

in greater depth, but time limits and funding constrains prevented this. Several

of the studies underway will continue in more depth and the results will be

published in future journal articles.

Specific objectives achieved include the following:

A. Radio noise (riometer) absorption measured by the MDAC polar

stations as a function of particle energy and type as measured by

OGO-6 was investigated and earlier theoretical work verified.

B. The anisotropy between the North and South polar regions was

investigated in detail.

31

100.0

10.0-0 SOUTH

- II- 'P I

C.): 1.0

I

-~~~~~ I

I

- I + -- ~~~~~~~~~~~~~~~~ 200I~~~~~

AA

-~~~~ A~· - 60

0.0100 06 12 18 00 06 12 18 00 06 12 18 00 06 12 18 00 06 12 18 00

I 23JUL I 24JUL 25 JUL 26JUL 27JUL

Figure 4-21. 23 July 1970 Solar Particle Event

32

CR11

103

10o2

1010o3

,.n2

APPROACHING

RECEDING

ToV

I

.103^ 29 MAR 70

10

10 I

103 2 31 JAN 70

102 P-

10 I I

103 P NOV 6

102

10 i I I I i

103 23 MAR 70102

10 . I

10o3 A 6 MAR 70

1o 2 hI- "_

10[0 1 2 3 4

DAYS5 6 7 8

Figure 4-22. Proton/Alpha 5-21 MeV/Nucleon

33

CR11

I I I

1 ^7 JUN 69

I

I6 .

FI I II

APPROACHING

10Z A A 30MAY 70

1

0 .1 7 JUN 69

1 r _ MEO

0.1 I a I l I I i,t %2. * -- - -- -U'-

10

1

10 2 21 JUL 70P P

10 1 , , I I I

In..'u

1

0.1

102

10

1102

in

RECEDING1

1

1 , , , ,

10

0202 A 6 MAR 70

10 \ - I

1, 0 1 3 0 1 2 3 4

DAYS

Figure 4-23. Proton/Alpha 16-35 MeV

5 6 7

CR11

8

34

29 MAR 70

I I . I I I I

31 JAN 70

) =

I I I I I I I

7 . ~ ~ ~ ~ ~

p A 2 NOV 69

I

41 1I

A A 25 SEP 69

V:

I

APPRO

RE(

102

10

1102

10

1102

)ACHING 10

1

102

10

1

1 o2

10

1

102

10

1

102

10

CEDING 1

10

102

10

102

10

1

* A 30 MAY 70

I L,~~ I I I I I

7 JUNE 69

I I I I I

29 MAR 70

P*p 21 JULY 70P

I I I I I I i

Akp p25 SEPT 69

I I l I I I I

\ ~~I I~ 31 JAN 70

I I ' IIII

• _t~ p ~PA2 NOV69

I- I

l I I I I I

23 MAR 70

A__ * 6 MAR 70

I I

0 1 2 3 4DAYS

5 6 7 8

Figure 4-24. Proton/Alpha 8-16 MeV/Q

35

CR1 1

C. The study of variations in particle access to a given polar region

was given as an objective in the proposal, based on our earlier ground

observations. These early observations and suggestions were pre-

sented several years before they were discussed by any other investi-

gator based either on ground or satellite measurements.

D. Primary emphasis was put on charged-particle entry and

propagation in the analysis and interpretation of the data. This

area of investigation is currently being developed into a PhD thesis

at the University of Melbourne by the Principal Investigator,

A. J. Masley.

E. Considerable effort has been expended on study and interpretation

of the proton-to-alpha particle ratio and the effects of interplanetary

propagation.

A large number of presentations and papers have been based on the MDAC

OGO-6 experiment, as shown in Section V. Papers are currently in prepara-

tion for publication on: (1) OGO-6 and riometer observations, (2) entry and

propagation, (3) proton-to-alpha particle ratios, and (4) theoretical studies

of particle trajectories.

Several papers should also result from the PhD thesis currently being prepared.

These will include a discussion of entry and propagation mechanisms and

detailed results on the latitude cutoff for protons and alpha particles as a

function of local time and season.

Many of the OGO-6 results have been and will continue to be used to guide

investigations to be carried out on the ATS-F experiment furnished by the same

investigator team and due for launch in early 1974. The OGO-6 results will

also allow a more complete interpretation of data continuously provided by the

MDAC North and South polar ground stations.

36

V. PAPERS AND PRESENTATIONS

1. Wolpert, M. H., A. J. Masley, P. R. Satterblom, and D. W. Burtis,"A Low Energy Solar Cosmic Ray Experiment for OGO-F," IEEE Trans-actions on Nuclear Science, Vol. NS-15, 238, 1968.

2. Masley, A. J., and P. R. Satterblom, "A Discussion of Solar CosmicRay Activity Near Sunspot Maximum," Acta Phys. Acad. Sci. Hungaricae,29, Suppl. 2, 513-519, 1970.

3. Masley, A. J., and P. R. Satterblom, "The 2 November 1969 SolarCosmic Ray Event," EOS Trans. AGU, Vol. 51, 409, 1970.

4. Satterblom, P. R., and A. J. Masley, "The 7 June 1969 Solar CosmicRay Event, " EOS Trans. AGU, Vol. 51, 409, 1970.

5. Masley, A. J., and P. R. Satterblom, "A Discussion of the2 November 1969 Solar Cosmic Ray Event," presented at AmericanAstronomical Society Solar Physics Meeting, Huntsville, Ala,Nov. 1970.

6. Masley, A. J., and P. R. Satterblom, "Observations During2 November 1969 Solar Cosmic Ray Events," EOS Trans, AGU,Vol. 51, 799, 1970.

7. Satterblom, P. R., and A. J. Masley, "The 25 September 1969 SolarCosmic Ray Event," EOS Trans. AGU, Vol. 51, 799, 1970.

8. Masley, A. J., J. W. McDonough, and P. R. Satterblomn, "SolarCosmic Ray Observations During 1969," Antarctic J. of the U. S.,5, 172, 1970.

9. Masley, A. J., P. R. Satterblom, E. D. Stone, and J. A. Lockwood,"Geomagnetic Storm of 1969 November -- Storm Morphology, " paperpresented at 52nd Annual AGU Meeting, Washington, D. C.April 12-16, 1971.

10. Masley, A. J., and W. P. Olson, ",Calculations of Charged ParticleAccess Into Polar Regions, " EOS Trans. AGU, 52, 315, 1971. Inpreparation, to be submitted to Journal of Geophysical Research.

11. Masley, A. J., and P. R. Satterblom, "Observations During the2 November 1969 Solar Cosmic Ray Event," paper presented at COSPARSymposium on the November 1969 Solar Particle Event, AFCRL,Bedford, Massachusetts, June 16-18, 1971.

12. Masley, A. J., and W. P. Olson, "Temporal Variations of ChargedParticle Access Into Polar Regions, " paper presented at 15th Gen. Assy.of Intl. Union of Geodesy and Geophysics, Moscow, August 2-14, 1971.

37

13. Masley, A. J., W. P. Olson, and K. A. Pfitzer, "Calculations ofCharged Particle Entry Into Polar Regions, " Conf. Papers, 12th Intl.Conf. on Cosmic Rays, Hobart, Australia, 2, 824, 1971.

14. Masley, A. J., and P. R. Satterblom, "Solar Cosmic Ray ObservationsDuring the September and November 1969 Events," Conf. Papers,12th Intl. Conf. on Cosmic Rays, Hobart, Australia, 5, 1849-1852, 1971.

15. Masley, A. J., and P. R. Satterblom, "Determination of First OpenField Line Location and Particle Access," EOS Trans. AGU, 52, 892,1971. In preparation, to be submitted to Journal of GeophysicalResearch.

16. Satterblom, P. R. and A. J. Masley, "Proton a-particle Ratios During1969-1970," EOS Trans. AGU, 52, 888, 1971. In preparation, to besubmitted to Journal of Geophysical Research.

17. Masley, A. J., and P. R. Satterblom, "Solar Cosmic Ray Events,1969 and 1970," Antarctic J. of the U.S., 6, 221, 1971.

18. Masley, A. J., and P. R. Satterblom, "Post Solar Maximum SolarCosmic Ray Activity," EOS Trans. AGU, 53, 479, 1972.

19. Baker, M. B., A. J. Masley, and P. R. Satterblom, "Solar ParticleMeasurements and Riometer Absorption," EOS Trans. AGU, 53, 477,1972. To be submitted to Journal of Geophysical Research.

20. Baker, M. B., P. R. Satterblom, A. J. Masley, and A. D. Goedeke,"Simultaneous Satellite and Riometer Measurements of Particles DuringSolar Cosmic Ray Events, " presented to COSPAR, Madrid, Spain,10-24 May, 1972.

21. Satterblom, P. R., and A. J. Masley, "Propagation of Protons andAlpha Particles from Solar Flares," EOS Trans. AGU, 53, 1056, 1972.

22. Baker, M. B., A. J. Masley, and P. R. Satterblom, "Polar RiometerObservations of the August 1972 Solar Proton Events," EOS Trans AGU,53, 1085, 1972.

23. Masley, A. J., P. R. Satterblom, and M. B. Baker, "Solar CosmicRay Investigations During 1971," Antarctic Journal, VII, 161, 1972.

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VI. ACKNOWLEDGMENTS

The investigators are indebted to several NASA scientists and engineers for

their contributions to the successful accomplishment of this program,

especially the following:

Dr. Enrico Mercanti for this efficient yet friendly and cooperative

direction, and Earle Painter and Ken Meese for their able assistance.

Nelson Spencer for his leadership and support.

W. E. Scull for his overall program direction.

Tom Fischetti for his interest and guidance.

Ed Szajna and Ron Durachka for their assistance in preparation of

the data tapes.

We are indebted to Professor Charles Barnes for allowing us to use the

California Institute of Technology tandem Van de Graaff for the calibration

of our experiment. His cooperation, interest, and assistance are greatly

appreciated. The assistance and support of Dr. H. Conzett, Ruth Mary

Larimer, and Harry Harrington during calibration at the 88-in. cyclotron

of the Lawrence Radiation Laboratory at UC Berkeley is gratefully acknowl-

edged. The contributions of both of these organizations considerably enhanced

the quality of the data obtained by this experiment.

Special thanks are due to Kayland Bradford and the team of people at TRW who

assisted in the testing and integration of this experiment and the successful

launch and operation of the spacecraft.

We appreciate the work done by the subcontractor, Marshall Laboratories,

especially Herb Rosenberg and Dick Benjamin.

Special contributions by several MDAC personnel are acknowledged and

appreciated:

M. H. Wolpert, project engineer

D. W. Burtis, electronic design and testing

Dr. K. A. Pfitzer, for major contributions in formulating

the data processing system

39

M. B. Baker, scientific analysis

Brice Atkinson, for preparation of several computer programs.

Also, we are grateful to the Instrumentation and Engineering Data Reduction

Department at MDAC under D. D. Huff for their assistance in processing and

plotting the data tapes.

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