Status of BESIII Representing BES collaboration Weiguo Li IHEP, CAS ICHEP04 Beijing, Aug. 18, 2004

BEPCII/BESIII Project BESIII Design and Current Status Schedule and Collaboration Summary

BEPCII/BESIII Project Covered by Zhang Chuang in this session Two rings

BEPCII Design Goals

Physics Channel C. M. Energy (GeV) Peak Lumi. (10 33 cm -2 s -1 ) Cross Section (nb) Events per Year J/  ~  10 9  ~  10 6  ~  10 9 D ~5 25  10 6 DsDs ~  10 6 DsDs ~  10 6 Expected Number of Events in One Year’s Running

工 工 BESIII Detector

systemBES III  XY = 130  m MDC  P/P = 0.5 %(1 GeV)  dE/dx = 6-7 % EMC  E/√E = 2.5 %(1 GeV)  z,  = 5-6mm (1 GeV) TOF  T = ps Barrel 110 ps endcap  counter 9- 8 layers Magnet 1.0 tesla BESIII Main Parameters

Main drift chamber Inner diameter: 63mm; Outer diameter: 810mm; length: 2400 mm;43 sense wire layers. Inner cylinder: 1.2 mm Carbon fiber, outer cylinder: 11 mm CF with 8 windows Outer endplate: 18 mm; stepped section 25mm; Al Signal wires : 25  m gold-plated tungsten Field wires: 110  m gold-plated Aluminum Small cell: inner---6*6 mm2, outer *8.1 mm2, Gas: He + C 3 H 8 (60/40) Wire resolution < 130  m Momentum dE/dX resolution: 6-7%.

Blue/red Stereo wires Black:Axial: 12+7 wires Structure and layer arrangement

图 1 多层多单元漂移室模型部分丝层布局结构示意图 Cell structure Drift velocity vs field

Resolution vs Drift Distance cosmic ray 16.4mm cell 14.0mm cell Primary ionization fluctuations Distortion of field Wire resolution of 130  m is achievable; beam test done at KEK, data is being analyzed; Outer and inner cylinders are ready; Endplates are in fabrication; feed through prototypes are fine;wiring machine will be ready soon;prototype of readout electronics. Wiring will start at the end of 2004

Time of Flight Counters Barrel ： 2*88 scintillator bars, BC408, 2.32 m long, 5cm thick Endcap ： scintillator bars resolution ： ps/layer PMT: Hamamatzu R5942 Endcap sideview Barrel mechanical

Source of errorsBarrel Time resolution Endcap time resolution One layer intrinsic time resolution 80 ～ 90ps 80-90ps Bunch time uncertainty 20ps Bunch length uncertainly 15mm ， 35ps MDC positioning precision 5mm,25ps10mm,50ps Electronics25ps Track length30ps Time walk correction10ps Total resolution for one layer 100 ～ 110ps110 ～ 120ps K/  separation: 0.8GeV. Factors contribute to the time resolution

Time of Flight system Beam test finished, intrinsic timing resolution of BC408 reached ~90ps for barrel and ~95ps for endcap, comparing with Eijen 200 scintillators PMT tested in 1T magnetic field Electronics using HPTDC tested, resolution ~ 18 ps Currently under study: –reflecting materials for scintillator bars –Testing facility for mass production –PID with Aerogel Cerenkov counters Start to order PMT and scintillator in 2005

Beam Test ： Intrinsic resolution of BC408 and EJ200 BarrelEndcap

CsI(Tl) EMC 6240 crystals, (5.2x 5.2 – 6.4 x 6.4) x 28cm 3 PD readout, noise <1000 ENC at lab Energy resolution: Position resolution: Tiled angle: theta ~ 1-3 o, phi ~ 1.5 o No wall between crystals, Quantity Saint-Gobain3000 SIC1920 Hamamatzu1320 Crystal production

no partition wall Mechanical support structure

Crystal productions have some delay, the quality is fine, no big problems expected; The devices for measuring crystal properties and PD are designed and are functioning The EMC monitoring system is designed Electronics are on schedule, <1000e at lab The mechanical support structure is designed, prototype being tested. Status

Light output > 33% of reference crystal ~5000 e/MeV Uniformity < 7% Radiation hardness Light output > 80% after 1krad Crystal size: Lateral,  m Crystal quality control

Coil: Single layer solenoid, steady field Cooling mode: In-direct cooling by two phase flow liquid helium Cable: Pure Al stabilized NbTi/Cu Fabrication technology:Inner winding Cold mass support: GFRP tension rod Thermal shield: Liquid Nitrogen plus multi-layer thermal insulation Flux return: Barrel/End yoke, pole tip BESIII Super-conducting magnet Cryostat Inner radius 1.375m Outer radius1.7m Length3.91m Coil Mean radius1.485m Length3.52m Cable dimension3.7mm*20m m Electrical parameters Central field1.0T Nominal current3250A Inductance2.1H Stored energy9.5MJ Cold mass3.6ton Total Weight14.6ton Radiation thickness2X 0

BESIII Super-conducting magnet SC cable –Hitachi cable Ltd., delivered SC magnet –Collaboration with WANG NMR INC., US. Current status –Engineer design completed –Winding machine ready –Supporting cylinder will be ready end of Aug. –Engineer design of cryogenics is nearly done –Start winding the magnet this Sep. –Magnet cooled down summer of 2005, then field mapping

 system : RPC 9 and 8 layers, 2000 m 2 Bakelite, no linseed oil 4cm strips, channels Production started (endcap) Noise less than 0.04 Hz/cm 2 Covered by ZHANG Jiawen in this session

Expected Performances Solid angle: 0.89 ， Barrel: Position resolution: 1.2 cm Minimum momentum ： 0.4GeV Efficiency: > 95% Punch-through: <15%- a few % μ efficiency and pion punch- through rate vs momentum

RPC prototypes

R&D: under neutron radiation After some time for recovery, all properties back to the level almost the same as before radiation.

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

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

Trigger simulation: MDC trigger Trigger System Design done, Trigger efficiency and background rejection meet the requirements Trigger boards being Designed.

DAQ System data transfer requirements Sub-DetectorChannels Drift Chamber (T+Q) Electromagnetic Calorimeter6240 Time of Flight (T+Q) Muon Counter9216 Trigger Total~ 30K L1 trigger rate: 4 KHz Event Size: 12 KBytes Bandwidth required after L1: 48 MByte/sec Bandwidth required on tape: 36 MByte/sec > 1000 current BESII system

DAQ System configuration

Some tests of power pc

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

Beam background: a serious issue Amp All Cu surfaces

Total Beam-related Backgrounds Backgrounds are simulated from - Synchrotron Radiation; - Beam-gas; - Touschek effect; - Injection. With some masks and shielding near detector Single rate Max: at MDC 40 K; TOF: 10K Dose/year at endcap EMC Max:~210rad/year, Ave:~ 50rad/year. Should be carefully monitored

BESIII Offline Software System (BOSS) A Team has been set up, most of the tasks are assigned Completed: –Three versions of software Framework –Currently based on Gaudi –A GEANT4 based MC with all sub-detectors –Preliminary reconstruction codes with most sub- detectors Three releases planned before end of 2006 Need more people to work on the reconstruction and prepare for the calibration

4 π- tracks in BESIII p= GeV |cosθ|<0.9 pion punch-through Hits in end-cap TOF

BESIII mechanics and return yoke Engineer design completed Contract for mechanics and return yoke awarded Pre-assembly this Nov. Start assembly next Feb. Preparation for installation started

BESIII Status Design has been finished Most of the R&D work successful Detailed Budget and CPM available Most of the budget have been contracted Mass production has been started: –CsI Crystals –RPC muon chambers –Support structure and Yoke –Superconducting magnet –Drift chamber structure

BESIII Schedule 11/2004: supporting structure/yoke installation 2-3/2005: endcap muon chamber installation 5/2005: magnet installation 10/2005: magnetic field mapping 2/2006: EMC installation 3/2006: MDC/TOF installation 7/2006: BESIII debug and commissioning, Cosmic ray 10/2006: BESIII detector in beam-line 11/2006: commissioning detector/machine

A few items are on critical path for BESIII Mechanical support and Yoke Mechanical support of Barrel EMC; Crystal production Super-conducting Magnet Offline software Technical Challenge Background issues PID, MDC, EMC performance; DAQ system

BESIII Collaboration There are about 18 Chinese institutes in BES collaboration, about 10 are actively involved in BESIII project, Physicists from US and Japan are participating in BESIII project, More foreign participants are welcome. Contact persons: or

Summary BESIII project is in good shape right now, We have to work hard to meet the challenges and difficulties ahead of us. I believe we should be able to complete BESIII project on time and with good quality, and start to take data in 2007.

Thanks

BEPCII Milestones May. 04 – Oct. 04. : –Linac upgrade –BESII detector removed Nov. 04 – March 05: SR running April 05 – Jan. 06: Long shutdown –Remove existing ring –Install two rings –Cryogenics system ready for SC devices, field mapping Feb.- Sep. 06: Tuning of machine + SR running Oct. 06 : BESIII detector moved into beam line Nov. 06 – Feb. 07 : Machine-detector tuning. Physics run by March 2007

Crystal size: front ： 5.2cm x 5.2cm rear ： 6.4cm x 6.4cm length ： 28cm Crystal production Quantity Saint-Gobain3000 SIC1920 Hamamatzu1320

EMC support module ( 1/60 )

BESIII Main Detector Components Small cell, He gas based drift chamber Time of Flight Counters CsI(Tl) crystal calorimeter RPC muon chamber system Super-conducting magnet of 1T