-

--a- ---f. w

Georgii Chelkov , August 16,1994

JINR Studies for a Tau-Charm Factory

Workshop on the Tau-Charm Factory in the Era of B-Factories and ._. ,< - CESR

August 15 and 16,1994

SLAC

451

I :

..-a - ---.r.. * REFERENCES

1. Proc. Tau-Charm Factory Workshop (Stanford, 1989) SLAC-REPORT-343, ed. L. Beers.

2. Proc. Tau lepton Physics Workshop ORSAY, fiance, September 18-22, lQQ@ ed. by M, Davier, BJean-Marie.

3. Proc. JINR Tau-Charm Factory Workshop, 1992. JINR, E1,9,13-92-98.

4. M.Perl ._, -_ -

5. J.Kirkby

6. R.H.Schindler

7. M.V.DaniIov et al

8. Y.Baconnier et al

9. K.K.Gan

10. W.H.Toki

11. N.Wermes

.

SLAC-PUB-5132( 1989) SLAC-PUB-5614( 1991)

SLAC-PUB-5666(1991).

CERN-EP/89-140;1989 CERN-PRE/Ql-13,lQQl.

SLAC-PUB-5202, 1990.

ITEP 67-90,lQQO.

CERN-AC-QO-07,lQQO.

SLAGPUB-4609,1988. SLAC-PUB-5005,1989

SLAC-PUB-5094,1989.

HD-PY-91/4,Heidelbtrg.

452

. . ..-a= - ---,r. -

. THE LEP DATA CONCLUSION:

“There are only three families of fundamental . fermions !”

U 0 d L

The results of experiments at LEP have shown that there are-no new neutrinos, charged lep- tons, or quarks with masses below 45 GeV/c’.

It therefore appears tshat the present three families of fundamental fermions will be the only ones that are experimentally accessible in the immediate - and perhaps far future.

453

LEPTONS

e- P- 7-

(ML) 0.51099906 105.658387 1784

f0.00000015 f0.000034 +2.7; -3.6

am m% f2.9~EW5 l f3.2*10-s f0.18

MEAN LIFE TIME >2-1022years (2.19703f0.00004)~10-6 s (0.303f0.008)~10-'* s

t

(5% -_ -r _ f1.82.10-3 2.6

DECAY MODES -_ -

prong - 86% --

e V&p = 100% -- p v/p, e 17.870 e-&v7 x 17.7%

r-v, *ll% e-S7,v,,y = 1.4% K-v, =0.7%

p-VT w 23% 7r-27r"v, % 7.5%

+- eTp,e e w 3.4.10-5 7r-37r"v, e 3.0% 99 &prong” z 14% 7r--7r--T+v, = 7.1%

n-p&+ e 5.4% n 5-prong” R 0.1% 2X+$X-v, ~6.10"

27r+3T-z"vz k:5*10-J n Lprong” < i .9-10-~

% UT

m,<17eV mu <0.27MeV m,c35MeV

454

- .

.

/

.

.

\

hi

Subject

Understand l-charged particle modes puzzle 7 .

Untangle multiple noand 77 in l-charged particle modes Precise measurement of B~(evv),B(pvv),B(nv), ~(h~(pv), and their ratio to 0.5%

Precise measurement of Cabibbo-suppressed modes

Full study of dynamics of 7 ---) evv, 7 ---) /WV analogous to /A ---) WV in detail .

Detailed study of 3-, 5-, 7-charged particle modes

Find and study rare allowed modes such as radiative decays and second-class currents

.Explore forbidden decay modes .-_

Precise measurement of 7 lifetime

mass to a few MeV/c2

Detect V,

Study interactions of V,

Precise low energy study of e+e- -+ r+r--, r+r-y

Precise high energy study of e+e- - r+r-, 7+7--y

Study of 2’ ---) 7+7-

Study of W- * 7-F

MYeasure B(D- * 7-F)

Measure B(DB ---) 7-F)

Measure B(B- + 7-F)

Make and study 7+7- atom

455

.-a- .--. _ .-. *

Tasks of the Tau-Charm Factory detector group

l Development (adaptation) of a physics programme for the JINR Tau-Charm Factory.

l Selection of the optimum detector design adequate to the physics programme and real conditions of the JINR. .--

l Setting up of expert groups that can carry out designing ._, -_ - and methodical research and become kernels of future col- laboration after the project is approved.

l Establishment of contacts with leading centres with a view to possible wide international collaboration within the frame- work of the JINR project.

456

.--

._, ,T -

WORKSHOP . on J I N R CTakFACTORY.

. @-dma,toet,JNSDdru) TentaiiWopb:

I. Physlos’lnvestigation program at CTau-factory- 1.1 Tau-leplon and tau+w@ino physics 12 Charmed meson phy& 1.3 JPsl-partlde physks 1.4 Charmed baryon physks 1.5 Other physk problems

2, Accelerdtbr physics .’ 3. Detector

3.1' S&Jl-ingle deledors ,32 TracMng system 3.3 ParUde IdenMcation system’ ,3.4 Elecbomagnetk calorimetry 3.5 Supercond,ctlng solenoid 3,6 Muon detedor 3.7 Trlggen 3,8 MonteCadoslmuMlon

4. Data acquisition and analysis system OraanizinaCommltlee: . ChaInan: D.Klss ’ ’ Depu!y ehdmlan: AN.shm

Membersi D&ett RP- yDe&ov N.Ahsm&dd

$~“L”/ i4izat

Lil.‘Onlsdlenko * &m

EAPerelsteln w+=

Workshop Secretary: Mh0edqhw All tinesponderxx should be addressed b:

Bednyakcw V. lab.of Nudear Problems, JIE.R,‘Heai Pat aria, P,O.&.3x 79,101ooo Moscow, USSR

FAXI (7095)200-2243 TELEXi Qll@l WIBNASU Emdl: CHELKOV@V%CERN.BlTNET

457

..-a - -- . _ ,-.. *

458

CONCLUSIONS

of The J?irst Workshop on JINR C-TAU Factory

29-31 May 1991, Dubna

_ .--

1. The CT -factory physics programme for the precision study of the properties of the T- lepton and c-quark-containing particles near their production threshold is of current im- portance and aimed at studying the fun- damental problems of particle physics. It can not be implemented at the existing-or planned facilities.

._, -_ -

2.

3.

_ 4.

In general, the research programmes pro- posed now for high-intensity e+ e- colliders (4 -) CT-, B-, Z-factories) complement one another and are likely to yield the best re- sults if fulfilled together.

Imp,lementation of this programme will take at least 10 years after putting into opera- tion the above installations.

As the research programme is rather wide, it is reasonable to construct at least two installations of each type, which will also ensure the necessary confidence level of the data obtained.

459

..-a. - -- f. - .c . 5. Being a project of a perfect facility for mod-

ern particle physics, the CT-factory and uni- versal detector project is relatively cheap and feasible for the JINR.

6. The significance of the project is far beyond the above-mentioned dent ific reasons:

l deve,lopment and construction of this col- lider allows a new modern basic facility of world class in the JINR for particle physics research;

.-- l participating iln this work based on the ad-

._, -_ _ .

. 0

vanced technological experience many spe- cialists (accelerator and other physicists, en- gineers, designers, workers) will improve their professional skills, which will raise the general level of the scientific research in the JINR; new competitive basic facility will allow the JINR to remain attractive to the scientists of the member-states for another 10-15 years and to attract scientists of other research centres; construction of the CT-factory in the JINR will allow many young specialists of the member-states to be trained according to the present-day requirements and Will be helpful in replenishing the JINR staff with talented youth.

. 460

- .

.-ax.- .-- f. - .-

STATUS REPORT ON THE JINR TAU CHARM FACTORY PROJECT.

A. SISSAKIAN, E. PERELSTEIN

1. INTRODUCTION.

The project of an electron- poeitron storage complex ie presently studied at JINR to provide promising inveatigationa in the Inetitute’e traditional field8 of elementary particle physics, nuclear phyeic8, condensed matter physics, M well a8 applied investigation8 [l]. The project discussed involvea: a high resolution neutron source (IREN), a Tau Charm Factory (TCF) d an an 8-10 GeV positron (electron) storage ring (NK-IO). The construc- tion of the complex ie expected to have three stagea. At the first stage, the high resolution neutron source is to be built. The IRFN conetruction decision was approved at the 76th cession of the JINR Scientific Council in June, 1994. The second stage is the construction of the Tau Charm Factory. A eucceseful discussion of the Tau Charm Factory proposal took place at the past 75th eesaion of the JINR Sientific Council in 1994. For succeasfull

.,. _. realization of the TCF project it ia expected to organize a wide international collaboration to include a8 many countries from all continent8 having an interest to Tau Charm Physics aa possible.

-We believe that the location of TCF or a similar installation at Dubna ha8 many ad- ._ A vantages. It would open new possibilities to advance higb energy phyeics in East European Countriee where JINR is a well-known scientific centre, to develop new high technologies .and to raise the education level of young people in thie region, a8 well a8 to create an international collaboration in this field of physics. JINR ha8 a ‘IGning Ccntre, and on this basis it ie possible to establish an International Univenrity at Dubna where ‘the par- ticle physics students could have their using practice at the modern facility such a8 TCF. Presently there are about 500 high energy phy8i&t8 in the JINR etaff. The development of the international collaboration around the JINR TCF will be baaed on a wide acce88 to TCF for a large number of visiting ecientists and students, the progrees with JINR’8 computer net communicatione, the geographical location of Dubna (near Moecow, near the international airport Sheremetyevo), the available infrastructure of JINR as an inter- national ecientific centre.

2. TAU CHARM FACTORY PHYSICS PROGRAMME.

The requirement8 for TCF phyeics, machine and detector have been discueeed at many wor~hops Pl,Pl, [41,[5l,~q* 7-h e scientific research programme for the Tau Charm Factory include8 tau-lepton and tau-neutrino phyeics, charmonium spectroscopy, CP violation experimenta, charmed baryon phyeics and meson spectroscopy.

The core of the experimental programme for Tau Charm Factories muet be: the study of propertiee of the eecond-generation quark8 and the third-generation leptons through iu- vestigations in tau-lepton physics, charmed meeon physics, charmonium physice, charmed

461

I :

..-a - -- . _ ~-.. * . Experiment

BES ARGUS CLEO ALEPH DELPHI OPAL L3

JINR

Collider BEPS DORIS CESR LEP LEP LEP LEP TCF TCF TCF

E&Gev) Number of T+T- 4 10’ 10 10 91 91 91 91

3.57 3.67 4.25

3.75 *lo6 2 -lo6 6 *IO’ 5 *IO’ 5 *IO’ 6 010’ 4 *lo6 2 *lo’ 4 40’

Table 1: r+r- production at c+e- collidere ( presented by Prof. Alan Weinetein). CESR: L > 2s l~2cm-2s-’ = 10pb-l/dq/ = l.5f6’1/yeor. CESR - upgrade: Nbn~li : 7 x l-+ 9 x 5+ I, = lO”(l996). B - facto&a: SLAC (3. loSScm-2s-‘), KEK (~c+‘cm-~s-~).

baryon physics. This ia the energy region where the BEPC facility recently built in Beijing (China) operates. Nevertheleee, the experimental etatistice for this energy regio! is far from being rich. So, one of the reasons for building Tau Charm Facto&s is to get higher

- hnninosity.- In Table 1 there are the tau- lepton pair production ratee for different centrea [7] and

for the JINR TCF. --’ ’ Besides, TCF allows one to study properties of tau-leptons and charmed baryons near their production threshold and thus to obtain high-quality information at a uniquely low background.

So TCF is an ideal instrument to investigate most interesting features of the Standard Model and the hadrone as a compoeite syetem [s]. It play8 a role of source of 7 and D-mesons with (5 1%).

N 10’ events per year which provide rather good etatistical accuracy

. 3. THE PRESENT STATUS OF THE ACCELERATOR PART OF THE

JINR TCF PROJECT.

Presently two TCF projecta with a centroof-m& energy range 3-5.7 GeV are being rtudied. The find one aime at CERN-ISR ite, bo taking advantage of the existing powerful

- injector, and the second one % directed toward8 construction at Dubna. Theee projects have many common featurea, ipart from the aite, because of well identified conetrainte and a strong collaboration between designem. We have three po&ble phasea for the TCF project [9].

The first pbsse of JINR TCF operation ia planned to be conventiond mcheme. The next one may be monochromatication [IO] or croesing angle scheme [12],which provides a luminosity of 3+5*10N cs2 8-1.

The injection complex consi& of a preinjector and a fast ‘booeter eynchrotron, where electrons and pwitrone are finally accelerated up to the main ring energy [ll]. The

-- 462

I :

-.e- - --s, ”

Standard Monochrom. Croe. angle echeme echeme scheme

Beam GeV energy, E 2.0 2.0 2.0 Luminosity, cm-28-i L l.O*lou 0.9W3 3.5.W CM. resolution, MeV energy @w 1.9 0.14 1.7 Circumference, m C 377.8 377.8 377.8 Natural emittance, nm

J.&J. 0.6;;!2.4 17.0 * 299

Damping partition numbers 2/l/l 0.6/l/2.4 Bending radiue in arc, m

r&7, 37g9 10.5 10.5

Damping timee, msec 18/35/34 41/25/l 1 Momentum compaction a 1.58~10-2 8.02* lO-s 1.59*10-2 Energy spread UB 6.6610” 7.32~10~ 5.89*10-’ Total current, A I 0.566 0,479 Number of particles per bunch Na 1.49*1011 1.26.10” 1.025:~o” Number of bun&e ka 30 30 150 RF voltage, MV V 8 5 7 RF frequency, MHz fiw 476 476 476, Harmonic number Q 600 600 600 Energy Ioss per turn, kV uo 226 143 199 Bunch length, mm QI 8.15 8.06 7.72 Bunch spacing, m sb 12.6 12.6 2.52 Required long: impedance, Ohm 1 Z,,/nl 0.25 0.18 0.27 Beta functions at I.P., m /!Yy& 0.20/0.01 0.01/0.15 0.50/0.01 Yerticd dispersion at I.P., m 0. 0.36 0. Beam-beam parameters 0.04/0.04 0.04/0.03 0.04/0.04

Table 2: List of parameters of tau-charm collider

preiijector energy 500 MeV will be also suitable for iuitid acceleration of particles for the Synchrotron Radiation (SR)- source NK-10 in future. The average luminosity is ensured at the level of 80 % of peak one. .

The conventional scheme is considered aa the basic one for the JINR TCF. The versatile design of the collider provides the possibility to work with the mordwomatization for the experiments requiring a small energy resolution [lo]. The borisontd crossing angle option

- with minimum modifications in the storage ring is diiuesed in [12]. Only interaction and eeparation region8 have been replaced, while keeping the arca and the long etraight section oppoeite to interaction point untouched. The list of TCF parameters for three options is given in Table 2.

The main featurea of the design prepared by JINR (Dubna), SRIEA (St. Petersburg), RIPR (St. Petersburg) on the base of the versatile lattice were discussed in [IO].

The duminum vacuum chamber of TCF is designed in such a manner that SR goes through next etraight section and is absorbed at the bending magnet end. Providing the

463

-*- chemical cleaning and heating of the vacuum chamber tbe outgaaaing rate of aluminum .---‘r. c - much lees then stimulated deborbtion. Using the combined pumpe one geb the pressure

. about 2*10-‘Pa at the abeorber location, which comaponds to the beam lifetime of 30 h. Tbe additional pump ia used for the pumping of tbe remaining part of vacuum volume and provides tbe pressure at the level %IO”Pa.

The 500 MHs superconducting RF cavities b planned to uee. The total value of SR and HOM loeeee at energy E = 2.0 GeV is of order 300 kW and the maximum RF voltage b of 8 MV for one ring. The RF power supply scheme for TCF ~II grounded on the principle of separate rupply of each cavity u&g the 80 kW Wyetrons developed at “SVETLANA” (St.Petereburg). Tbe RF power rupplier coneiab of 4 independent FR lines with the total output power 320 kW.

References [I] A.N.Sieeakian. Previoutr Rochester.

[2] Proceed. of tbe Tau-Charm Factory Workshop, SLAGReport-343,1989.

[3] Meeting on tbe Tar&harm Factory Detector and Machine, ed. by J. Kirkby and J. M. Quesada, University of Seville, Andalucia, Spain, 29 April-2 May 1991.

[4] Third Worksbop on the Tau-Charm Factory, 1-6 June 1993, Marbella, Spain, Editions . . _-- Frontieree, 1994.

[S] Proceed. of the Workshop on JINR c-tau Factory, 29-31 May 1991, JINR, Dubna, Dl, 9, 13-92-98. ._. -_ -

[S] Proceed. of the II Worksbop on JINR c-tau Factory, 27-29 April 1993, JINR, Dubna, Dl, 9, 13-93-459.

Factory. Marbella, Spain, Editions Frontieretr, 1994. .

[7] A.J.Wei.uetein. In Proceediuge of the Third Workshop on the Tar&harm Factory. Marbella, Spain, Editions Frontierea, 1994.

[8] E. Kuraev, Physical program on Cl- tau Factories, Proceedings of the 2nd Workshop on JINR Tar&harm Factory. Dl,9,13-93-459, Dubna, 1993.

[9] P. Beloshitsky, J. Le Duff, B. Mouton, E. Perelstein, Modern view on Tau- Charm Factory Design Principles, Preprint LAL RT/94-05, Oreay, 1994.

[lo] E. Perelstein e. a.“Further study of JINR Tau- Charm Factory”( Proceed. of the 1993 Particle Accelerat. hnf., Washington, 1993, p. 2042)

[l l] E. A. Perelsteiu e.a n JINR Tau-Charm Factory Study” (Proceeding of XV Interna- tional Conference on High Energy Acceleratora, Hamburg,l992)

[12] P. F. Beloehitsky, E. A. Perebtein, Horizontal Crab- Croeaing Scheme for Tau- Charm Factory. EPAC 94, London, 1994.

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