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Weiguo Li Institute of High Energy Physics Sep. 16, 2002

Overview of BEPCII/BESIII PROJECT BESIII International Review Sep. 16-18, 2002, Beijing. Weiguo Li Institute of High Energy Physics Sep. 16, 2002. Goals of the BESIII review Examine the overall design of BESIII detector, if this design can accomplish the goals?

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Weiguo Li Institute of High Energy Physics Sep. 16, 2002

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  1. Overview of BEPCII/BESIII PROJECT BESIII International Review Sep. 16-18, 2002, Beijing Weiguo Li Institute of High Energy Physics Sep. 16, 2002

  2. Goals of the BESIII review • Examine the overall design of BESIII detector, if this design can accomplish the goals? • Examine the technical feasibility of detector overall design, the designs of all the sub-systems • Suggestions and opinions for important detector design choices, such as the magnet and the EMC • Suggestions and comments for further detector design, R&D, detector manufacture, schedule and cost

  3. Introduction • BEPCII Design • BESIII Design • BESIII Collaboration • Summary

  4. Introduction The BES Collaboration Korea (4) Korea University Seoul National University Chonbuk National University Gyeongsang Nat. Univ. USA (4) University of Hawaii University of Texas at Dallas Colorado State University Stanford Linear Accelerator Center UK (1) Queen Mary University China (18) IHEP of CAS Univ. of Sci. and Tech. of China Shandong Univ., Zhejiang Univ. Huazhong Normal Univ. Shanghai Jiaotong Univ. Peking Univ., CCAST Wuhan Univ., Nankai Univ. Henan Normal Univ. Hunan Univ., Liaoning Univ. Tsinghua Univ., Sichuan Univ. Guangxi Univ., Guangxi Normal Univ. Jiangsu Normal Univ. Japan (5) Nikow University Tokyo Institute of Technology Miyazaki University KEK U. Tokyo

  5. BES Current Status Data Collected with BESIand BESII

  6. BESII Detector (1995-1997 upgrade) VC: xy = 100 m TOF: T = 180 ps  counter: r= 3 cm MDC: xy = 250 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.4 %  = 7.9 mr B field: 0.4 T p/p=1.8(1+p2) z = 2.3 cm Dead time/event: 〈10 ms

  7. BESMain Physics Results • Precise Mass Measurement of  lepton. • 2-5 GeV R measurement. • Systematic study of (2s) decays. • Systematic study of J/ decays. ObtainfDs from Ds pure leptonic decay. • Measure Br(DS) in model independent way. • BES has 116 entries in PDG. • BES has 74 invited talk，published 216 papers, 48 papers in world-class journals.

  8. Physics Window for BEPC Two major directions in world HEP: • High Energy Frontier：Search for Higgs particle and beyond STM particles and phenomena. • High precision frontier：high statistics and high precision，check STM，search for phenomena beyond STM. Considering the new developments of world HEP, the main physics window for BEPC is precise measurement of charm and charmonium physics, and search for new phenomena. Advantages: huge cross section at J/ and (2s) resonance simple topology and low background at threshold Important area to study QCD，perturbative and non-perturbative QCD，can search for new physics.

  9. BEPC II Physic Goals • Precise measurements of J/、(2s)、(3770）Decays • Precise measurement of CKM parameters • Light quark hadron spectroscopy • Excited baryon spectroscopy • Other D and Ds physics: • precise measurement of D and Ds decays • measurement of fD, fDs • D0 –D0 mixing • Check VDM, NRQCD, PQCD, study  puzzle

  10. BEPC II Physics Goals （2） • Mechanism of hadron production，low energy QCD： precise R measurement •  physics：charged current，m and m • Search for new particles: 1P1 、c ?、glueballs、quark-gluon hybrid、exotic states… • Search for new phenomena: • rare decays; • lepton number violation; • CP violation in J/ and (2s) decays;

  11. BEPC Future Development: BEPCII • Precise measurements need: • High statistics → high luminosity machine • Small systematic error→ high performance detector • BEPC will run at J/ and (2s)，with huge cross-section, also at (3770), 4.03 or 4.14 GeV for Ds • Need to have major upgrade for machine and detector (BEPCII / BESIII)， to increase machine luminosity by more than one order of magnitude with relatively small budget and in a relatively short time.

  12. Competition in tau-charm physics • CESR, USA runs at 10GeV for B physics, because it can hardly compete with two B factories，on the other hand, there are important and interesting physics at tau-charm energy region as demonstrated at BEPC, plans to reduce the collision energy by installing a series of SC wigglers, expected lum.（1.5 – 3)x1032cm-2s-1。 • VEPP-4M, Novosibirsk, Russia, has a similar plan. • BEPC/BES can not enjoy the advantage of unique e+e- collider in this energy region any more，strong competition. • BEPC II single ring design can not ensure competitive edge in the race.

  13. BEPC II Double ring Design • In the existing BEPC tunnel, add another ring, cross over at south and north points, two equal rings for electrons and positrons.Advanced double-ring collision technology. • 93 bunches，total current > 0.9A in each ring. Collision spacing：8 ns. • In south, collision with large cross-angle（±11 mr）. • Calculated luminosity：1033 cm-2 s-1 @ 3.78GeV. • In north cross point, connecting SR beam between two outer rings, in south cross point, use dipole magnet to bend the beam back to outer ring. • SR run ：250mA @ 2.5 GeV. • Major detector upgrade：BES III. Luminosity of BEPCII is a factor of 3-7 of that of CESRc, more potential, and technically less challenge. Budget increased by 50％.

  14. BEPC Upgrade: BEPC II — double ring RF RF SR + - e e IP

  15. BEPCIIDesign Goals Increase beam current，reduce beam size

  16. Wood Model Space Study for Double Ring

  17. Luminosity Increase D.R.: multi bunches h~400,kb=1 93 Ib=9.8mA, xy=0.04 Micro-b:by*=5cm  1.5 cm Super-conducting magnet Impedance red. and SC RF cavity sz=5cm  <1.5cm (LBEPCII/ LBEPC)D.R.=(5.5/1.5) 93  9.8/35=96 LBEPC=1.010 31 cm-2s-1 LBEPCII =110 33 cm-2s-1

  18. parameter unit BEPC BEPCII y* cm 5.0 ～ 1.5 Bunch number kb 1 93 xy 0.04 0.04 Beam current Ib mA 35 9.8 factor for lum. increase 1 ～ 100 Means of lum. increase (E = 1.89 GeV) BEPCII cross-angle collision：2 x 11mr

  19. BEPCII Main Parameters

  20. BEPCII/BEPC/CESRcComparison

  21. Linac Injection rate: 5 mA/min. 50 mA/min. New positron source Stability and reliability Einj= 1.55-1.89 GeV 500MHz SC RF System SC RF Technology Power source and low level Cryogenics… Injection Magnets Power supplies Vacuum system SC Q magnet and IP Beam instrumentation Control system BEPCII Key Technologies and Challenges

  22. Linac Upgrade • Requirements: • Positron injection rate 5mA/min. 50 mA/min.; • Energy 1.3 GeV 1.55 ~ 1.89 GeV; • Use 45MW Klystron,upgrade RF source, replace 8 aged acceleration tubes； • Bombarding energy for positron 150 MeV 240 MeV; • Electron gun beam intensity 5A10A； • Produce new positron source, improving efficiency； • Improve focus and orbit-correction system； • Repetition rate 12.5 Hz  50 Hz； • Pulse duration 2.5ns1ns； • Possibility of double pulse injection (fRF/fLinac=7/40);

  23. means and factors for increase injection rate

  24. SC RF System • Requirements： • Sufficient voltage Sufficient power • reducing coupling instability  stability, reliability • Measures: collaborate with SSRF, Cornell and KEK，using existing technology.

  25. Super-conducting CavityCESR-type Cavity (ACCEL)KEKB-type Cavity(Mitsubishi ) • IHEP/KEK/SSRF collaborating group will optimize the cavity design, follow the manufacture process and technology, master the required techniques for operating and repairing the cavities.

  26. ( m ) field length Q 16.7 T/m 0.4 四 极 线 圈 0.2 T/m 0.4 斜 四 极 线 圈 SR 0.645 0.4 偏 转 线 圈 2.6 0.5 反 抵 螺 线 管 ~ 1.2 ~0.4 屏蔽螺线管 0.0528 0.4 水平 校正 线 圈 0.0528 0.4 垂直 校正 线 圈 Interaction point and SC Q magnet

  27. Beam Feedback System • Challenge：How to insure collision? • Beam-beam bending and scanning techniques： • Beam-beam bending：accelerator physics • Bending measurement ：beam instrumentation • Scan feedback ：automatic control

  28. Particle Energy Single Ring（1.2fb-1） Double Ring (4fb-1) D0  7.0106 2.3107 D+  5.0106 1.7107 Ds 4.14GeV 2.0106 4106 +- 3.57GeV 3.67GeV 0.6106 2.9106 0.2107 0.96107 J/ 3-4109 6-10109  0.6109 2109 BES III Expected Event Rates At  1033,at J/ and 4.14 GeV, ~0.61033

  29. BESIII Design Goals • High event rate：lum. :1033cm-2 s-1 and bunch spacing 8ns，hardware trigger rate: 4000 Hz，putting on mass medium: 3000 Hz. • Improve detector resolutions , especially for photons • Improve particle identification • Enlarge detector solid angle acceptance • Design interaction region to fit sc Q magnets

  30. Schematic of BESIII Detector

  31. BESIII Main Sub-systems • CsI EM Calorimeter:E/E ~3.5%@1GeV (inc. dead material) • MDC: small cell, Al field wire andHe-based gas P/P (1GeV) = 1.4 %@0.4T,0.6 %@1T,dE/dx = 6-7 % • Time of Flight: T: barrel90 ps；endcap110 ps • counter(RPC):readout strip width： ~4 cm • Luminosity Monitor(LM) L/ L = 3-5% • SC Solenoid：1 Tesla, I.R. 1.32 m, Length 3.8 m • New Trigger and Online system for multi-bunch and high lum. Operation, 4000Hz, 3000Hz to mass storage • New Electronics：pipeline operation • Offline computing: PC farm, mass storage

  32. Small cell, 46-47 layers He based gas HeC3H8 ( 60:40) Position resolution 130 m Mom. Resolution 0.6% at 1 GeV at 1 Tesla 1.4% at 1 GeV at 0.4 Tesla

  33. Dimensions need final tuning BESIII mechanical structure

  34. BESIII Electronics specification list Feb. 21, 2002 Item time measurement Charge measurement Count rate per channel Information provided to trigger Number of channel σt INL Range Cross- talk Number of channels σQ INL Dynamic range Cross- talk Type Quant. MDC 9000 0.5-1 ns ≤0.5% 0-400ns 9000 5fc ≤2% 15 fc - 1800fc 1% 30 k/s hit TOF + CCT 352+ 104 ≤25 ps 0- 60ns 456 12bits(ENOB) ≤2% 20mv – 4v 2-4 k/s hit 456 EMC BAR 8064+ 1800 0.16 fc200KeV 1 % 0.5fc - 1500fc 0.3 % 1 k/s Summation Of analog EMC (End) 1800 0.16fc 1 % 0.5fc - 1500fc 0.3 % 1 k/s Summation Of analog Mu Chan ~10000 Spec Considering multiple hit time measurement

  35. Comparisons between BESIII and BESII

  36. Worse mom. Resolution, Better low mom. efficiency BESIII detector with existing magnet

  37. Monte Carlo simulation show: because lum. Increase by two-orders of magnitude, a factor of 3 – 7 of that of CLEOc，BES III can obtain many important results in tau-charm physics Topics： Precise measure CKM parameters Precise R measurement Search for glueballs, determine spin and parity Search for 1P1 BESIII Expected Physics Results

  38. Physics example 1：precise measure CKM matrix • Measure pure-leptonic and semi-leptonic decay Br. Fractions of charm mesons to determine Vcd and Vcs • Measure hadronic decay Br. Fractions of charm mesons for determine Vcb • Measure fD and fDs for determiningVtd and Vts • Measure semi-leptonic shape of D and Ds for Vub • CKM unitarity check

  39. Br. Fractions of D decays（involving leptons）

  40. Physics example 2：R measurement

  41. Physics example 3：Search for 1P1 • y(2S)  p0 1 P 1 •  ggg hc  ggg 4K Br = (1.2 – 3.3)×10-6 • 1P1: 450-1200 evts/year • Background: y(2S)  • g cc1, gcc2,, hy, p0p0y

  42. Other expected physics reaches and background study by MC simulation will be covered by Dr. Wang Yifang Most of the main detector sub-systems will be covered by other speakers, I will say a few words about these sub-systems which are not presented separately today. Interaction region Mechanical preliminary design Slow Control

  43. Interaction Region • It is very compact at IR, very close cooperation is needed in the designs of detector and machine components at IR • Understand the space sharing, the support, vacuum tight • Understand the backgrounds from machine and how to reduce them, good vacuum near detector is required • - Beam loss calculation (masks) • - Synchrotron radiation (masks) • - Heating effect (cooling if necessary) • Understand the effects of thefringefield from SCQ to the detector • performances, the preliminary study shows that, field uniformity • should be better than 5% in most of the MDC volume • Center of beam pipe will be a double-wall Be pipe

  44. BESIII Mechanical design and Detector Hall Detector on two rail pads to move in south-north Iron Yoke Barrel~ 285 tons; endcap ~252 tons. at both sides between barrel and endcap, there should be a slot of 1100x 80mm for each side of octagon on every terminal surface of the barrel of yoke, for cable space.

  45. Assembled Structure, test assembling at factory

  46. Movable endcap yoke; reposition for field stability endcap EMC supporting and moving design, removing and reconnecting cables should not change the gain.

  47. Arrangements of electronic crates, moving with detector

  48. Arrangements for cooling water, gas, cables

  49. Slow control systemRequired measurements from detector and electronics • Temperature measurement: > 1000 • EMC CsI , 600 ; MDC 16; , 150; electronics crates, 300; cable rack, 100; environment, 100; • 2. Humidity measurement: ~250 • CsI, 200 ; MDC, 8; electronics, 20; environment, 30; • 3. Low HV of VME crates: 500. • 4. MDC gas：8. • 5. Voltage of power supply: several. • 6. Other measurements? Magnetic field; parameters in SC magnet and cryogenics; HV parameters for detectors; radiation dose; He leakage; flammable gas;others.

  50. ONE WIRE BUS can be used to read these signals out Probe/master, doing R&D 64 bit W. A. O（unique code worldwide), 12 bit DATE Temperature probe: DS18B20,22 RMB/probe humidity probe: LTM8802, ~150 RMB/probe 1. Humidity range: 1~99%，typical precision: 3%. 2. Temperature range: -30℃~60℃，accuracy 0.5 ℃ D . C voltage probe: DS2438/ LTM8805, several dozens of RMB/probe analog voltage:0～10V（resolution：0.01V） Light-decoupling between PC and master to reduce noise pickup,LTM－4850/2dual-port RS－485 card

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