1 BESIII PROJECT Zhen ’ An LIU Inst. Of High Energy Physics Representing BEPCII/BESIII Team QWG Meeting Oct , 2004 IHEP, Beijing

2 The Beijing Electron Positron Collider Linac,Transportation Line, Storage Ring,BES,BSRF L ~ ~5  /cm 2  s at J/  peak E cm ~2-5 GeV Construction: A unique e + e - machine in the  -charm energy region since 1989.

3 BESII Detector ( upgrade ) VC:  xy = 100  m TOF:  T = 180 ps  counter:  r  = 3 cm MDC:  xy = 200  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+p 2 )  z = 2.3 cm Dead time/event: 10 ms

4 BES BES Main Physics Results Data Taken: 66M J/  events, 18M  events, 33 pb -1  (3770)events, 5 pb -1  data, 22 pb - 1 Ds data  Precise Mass Measurement of  lepton.  2-5 GeV R measurement.  Systematic study of  (2S) decays.  Systematic study of J/  decays.  Obtain f Ds from Ds pure leptonic decay.  Measure Br(D S   ) in model independent way.  BES has 116 entries in PDG.

5 The need for upgrade Interesting physics limited by statistics: glueball/hybrid searches, CKM matrix elements, DDbar mixing,  puzzle, non-pQCD … Large systematic error due to limited resolution Detector is aging Multi-bunch mode & High event rate On Feb. 10, 2003, the Chinese government, the state council, approved officially the BEPCII/BESIII upgrade project

6 BEPCII: High Lumi. Large Angle Double – ring Collider Build new ring inside existing tunnel. Two half new rings and two half old rings cross at two IR’s, forming a double ring collider. 500MHz SC cavity

7 Double ring installation – Wood model No spacing problems No spacing problems

8 BEPCII Design goal

9 Passed SLAC review in May BEPCII main parameters Energy E(GeV)1.89Energy spread(10 -4 ) σ e 5.16 Circumference C(m)237.53Emittance ε x /ε y (nm)144/2.2 Harmonic number h396Momentum compact α p RF frequency f rf (MHz)499.8β * x /β * y (m)1/0.015 RF Voltage V rf (MV)1.5Tunes ν x /ν y /ν z 6.57/7.6/0.034 Energy loss/turn U 0 (keV) 121Chromaticities ν ’ x /ν ’ y -11.9/-25.4 Damping time τ x /τ y /τ z (ms) 25/25/12.5Natural bunch length σ z0 (cm)1.3 Total current/beam I(A)0.91 Crossing angle  (mrad) ±11 SR Power P(kW)110Piwinski angle Φ(rad)0.435 Bunch number N b 93Bunch spacing S b (m)2.4 Bunch current I b (mA)9.8 Beam-beam parameter  x /  y 0.04/0.04 Particle number N t 4.5×10 12 Luminosity(10 33 cm -2 s -1 ) L 0 1.0

10 The BESIII Detector small cell, He gas based drift chamber CsI(Tl) crystal calorimeter Superconducti ng magnet of 1T PID system based on TOF RPC muon chamber system

11 Sub-detectorBESIIBES IIICLEOc  XY = 250  m130  m90  m MDC  pt /P t GeV %  dE/dx = 8.5 % 6-7 %6% EMC  E  xy = 1GeV 2.5 % 0.5cm 2.0% 0.3 cm TOF180 ps 90 psRich  counter 3 layers9 layersNo magnet0.4 T 1.0 T The detector of BESIII,BESII and CLEOc

12 Physics at BEPCII/BESIII Precision measurement of CKM matrix Precision test of Standard Model QCD and hadron production Light hadron spectroscopy Charmonium physics Search for new physics

13 Physics to be studied in  -charm region  Search for glueballs, quark-gluon hybrids and exotic states  Charmonium Spectroscopy and decay properties  Precision measurement of R  Tau physics: tau mass, tau-neutrino mass, decay properties, Lorenz structure of charged current, CP violation in tau decays …  Charm physics: including decay properties of D and D s, f D and f Ds; ; charmed baryons.  Light quark spectroscopy, m c  Testing QCD, QCD technologies, CKM parameters  New Physics: rare decays, oscillations, CP violations in c- hadrons  …..

14 Event statistics at BESIII Physics Channel Energy (GeV) Luminosity (10 33 cm –2 s –1 ) Events/year J/  ×10 10  ×10 7  ’ ×10 9 D ×10 7 Ds ×10 6 Ds ×10 6 *CLEO took 10 nb D production cross section while we took 5 nb

15 For more detailed information and description of BESIII physics studies please refer to sep03/WS2talks/future/harris_BESIII.ppt

16 Schedule 5/2004: BESII detector was removed already 11/2004: supporting structure/york installation 3/2005: muon chamber installation 5/2005: magnet installation 10/2005: magnetic field mapping 2/2006: EMC installation 3/2006: MDC/TOF installation 6/2006: Cosmic-ray run 9/2006: BESIII detector in place 12/2006: tuning of detector/machine

17 Parameters and Current Status of BESIII

18 Main drift chamber Inner diameter: 63mm; Outer diameter: 810mm; length: 2400 mm Inner cylinder: 1 mm Carbon fiber, outer cylinder: 10 mm CF with 8 windows End flange: 18 mm thick Al 7075 ( 6 steps) 7000 Signal wires : 25(3% Rhenium)  m gold-plated tungsten Field wires: 110  m gold-plated Aluminum Small cell: inner---6*6 mm2, outer *8.2 mm2, Gas: He + C 3 H 8 (60/40) Momentum resolution 1 GeV/c): dE/dX resolution: 6-7%.

GeV/c π

20 MDC wiring machine

21 MDC electronics Preamp VMEbus Optical transmissio n MQT Clock Trigger Timing Wire Signal dE/dx Q Measurement T Measurement Calibration Amp + Shaper + Timing Readout Control Trigger Fan out  T < 0.5 ns, ns, INL <0.5%  Q < 5fc, fc, INL<2% Design have been finished, several prototypes have been successfully tested

22 EMC: CsI(Tl) crystals 6300 crystals, (5.2x 5.2 – 6.4 x 6.4) x 28cm 3 (15 X 0 ) PD readout, noise ~1100 ENC Energy resolution: Position resolution: Tiled angle: theta ~ 1-3 o, phi ~ 1.5 o Minimum materials between crystals

23 CsI Crystal production : SIC, Hammamatzu, Saint-Gobain

24 no partition wall Mechanical support structure

25 Assembling module of the Al-cells

26 EMC electronics pream p Main amplifier CLK L1 L1Reset Buffer full 10 bit ADC T/Q info. Local Buffer Global Buffer Fan out Trigger CLK L1 CHK Baffer full Test, DAC SCLK ， DIN Analog Sum ÷2 ×1 ×16 VMEVME TEST Control On crystal σ Q < 0.16 fc (1000 ENC) 0.5fc ～ 1500fc, 15bit Cross talk: <0.3%, INL<1% Design have been finished, several prototypes have been successfully tested

27 Super-conducting magnet Al stabilized NbTi/Cu conductor from Hitachi 1.0 T, <5% non-uniformity 921 turns, R = m, L=3.52m, cold mass 3.6t Thickness: 1.92 X 0 Inner-winding method

28 SC magnet winding machine Windingmachi ne and dummy coil Suport cylinder Winding machine

29 Particle ID: TOF system 392 pieces BC408, 2.4 m long, 5cm thick Time resolution ps/layer PMT: Hamamatzu R5942 图 桶部光电倍增管的支撑环， 内外两层共 176 个孔。

30 Beam Test ： Intrinsic resolution of BC408/EJ200 Barrel ： < 90 ps Endcap ： < 94 ps

31 TOF electronics Specifications: –Time measurement : <25ps –Charge measurement: 4mv~4V, 10 bit –Fast trigger signal System configuration: –preamplifier Bilinear Gain Stage + Fully Differential Output Stage –Frontend electronics(9U VME Boards) time/Q measurement ， HPTDC based, 25 ps –Clock synchronized with the RF cavity 500MHz signal clock signal cable: Phase Stabilized Optical Fiber (PSOF) Design have been finished, several prototypes have been successfully tested

32  system : RPC 9 layers, 2000 m 2 Bakelite, no linseed oil 4cm strips, channels Tens of prototypes (up to 1*0.6 m 2 ) Noise less than 0.2 Hz/cm 2

33 RPC production underway in the clean room

34 μ counter readout RPC PPC Input /output module Readout module System controller VME crate JTAG controller Power supply L1/CLK/Reset/Check… Design have been finished, prototypes have been successfully tested, production ready

35 Trigger system Event rate: Good event rate: ~ 2000 Hz Bhabha evt rate: ~800Hz Cosmic-ray rate: 10:1 Beam bg rate: 10000:1 Total event rate ： 4000 Hz Pipeline: –BEPCII in multi-bunch mode (93 ) ， bunch spacing: 8ns trigegr latency: 6.4  s ， events stored in pipeline buffer No dead time due to trigger Largely use optical fibers, FPGA, …

36 Trigger system ： configuration Global Trigger Logic 6.4  s TOF MDC EMC MU DISC Mu track DISC TrigSum Track Finder Etotal Energy Hit/Seg Count Track Seg. Finder DAQ RF TTC TC Sum L1P CLOCK Track Match Energy Balance Cluster Counting Design largely based on FPGA technology have been designed, prototypes underway

37 Block Diagram of DAQ Architecture DAQ system based on VME/PowerPC and PC farm have been designed, mini-version setup, software underway

38 BESIII magnetic yoke and mechanics

39 Beam background: a serious issue Amp All Cu surfaces Total dose near the interaction region ~ 150 MeV/  s < 20 CsI crystals < 20 MDC electronics < 1 TOF OK for safety MDC < 20 KHz/wire TOF 500 KeV EMC 100 KeV Careful MC study has been made.

40 Beam pipe and shielding Be beam pipe: 30 cm long, 63mm in diameter, 2 layers HOM power: 200W, SR: < 24 W 20 mm Gold plating to reduce backgrounds Liquid cooling channel between beam pipeLiquid cooling channel between beam pipe 20 mm Tungsten shielding

41 Other systems Offline computing environment based on a large scale PC farm is under study MC based on GEANT4, first reconstruction framework released, sub-detector reconstruction code underway

42 International collaboration IHEP, Beijing Beijing University, Beijing Tsinghua University, Beijing USTC, Hefei National Central University, Taipei KEK, Tokyo University, Tokyo Hawaii University, Honolulu Washington University, Seattle More collaborators welcomed

43 Summary The BEPCII/BESIII has been approved officially by the Chinese government The BESIII detector design is finished, prototyping is successful, mass production have been started Rich physics after CLEO-c(upgrade of BEPCII to 3*10 33 cm -2 s -1 is possible) Collaborators are welcomed!

44 Thanks

45 Event statistics at BESIII Physics Channel Energy (GeV) Luminosity (10 33 cm –2 s –1 ) Events/year J/  ×10 10  ×10 7  ’ ×10 9 D ×10 7 Ds ×10 6 Ds ×10 6 *CLEO took 10 nb D production cross section while we took 5 nb