Status of BESIII Representing BES collaboration Weiguo Li IHEP,
CAS [email protected] ICHEP04 Beijing, Aug. 18, 2004
Slide 2
BEPCII/BESIII Project BESIII Design and Current Status Schedule
and Collaboration Summary
Slide 3
BEPCII/BESIII Project Covered by Zhang Chuang in this session
Two rings
Slide 4
BEPCII Design Goals
Slide 5
Physics Channel C. M. Energy (GeV) Peak Lumi. (10 33 cm -2 s -1
) Cross Section (nb) Events per Year J/ 3.0970.6~3400 10 10 9
3.6701.0~2.4 12 10 6 3.6861.0~640 3.0 10 9 D3.7701.0~5 25 10 6 DsDs
4.0300.6~0.32 1.0 10 6 DsDs 4.1400.6~0.67 2.0 10 6 Expected Number
of Events in One Years Running
Slide 6
BESIII Detector
Slide 7
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 = 90-100 ps Barrel
110 ps endcap counter 9- 8 layers Magnet 1.0 tesla BESIII Main
Parameters
Slide 8
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 7075 6796 Signal wires : 25 m
gold-plated tungsten 21884 Field wires: 110 m gold-plated Aluminum
Small cell: inner---6*6 mm2, outer--- 8.1*8.1 mm2, Gas: He + C 3 H
8 (60/40) Wire resolution < 130 m Momentum resolution@1GeV:
dE/dX resolution: 6-7%.
Slide 9
Blue/red Stereo wires Black:Axial: 12+7 wires Structure and
layer arrangement
Slide 10
1 Cell structure Drift velocity vs field
Slide 11
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
Slide 12
Time of Flight Counters Barrel 2*88 scintillator bars, BC408,
2.32 m long, 5cm thick Endcap 48+48 scintillator bars resolution
100-110 ps/layer PMT: Hamamatzu R5942 Endcap sideview Barrel
mechanical
Slide 13
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
Slide 14
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
Slide 15
Beam Test Intrinsic resolution of BC408 and EJ200
BarrelEndcap
Slide 16
CsI(Tl) EMC 6240 crystals, (5.2x 5.2 6.4 x 6.4) x 28cm 3 PD
readout, noise
Light output > 33% of reference crystal ~5000 e/MeV
Uniformity < 7% Radiation hardness Light output > 80% after
1krad Crystal size: Lateral, +0 -200 m Crystal quality control
Slide 20
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
Slide 21
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
Slide 22
system : RPC 9 and 8 layers, 2000 m 2 Bakelite, no linseed oil
4cm strips, 10000 channels Production started (endcap) Noise less
than 0.04 Hz/cm 2 Covered by ZHANG Jiawen in this session
Slide 23
Expected Performances Solid angle: 0.89 Barrel: 0.62- 0.77
Position resolution: 1.2 cm Minimum momentum 0.4GeV Efficiency:
> 95% Punch-through:
DAQ System data transfer requirements Sub-DetectorChannels
Drift Chamber (T+Q)6796+6796 Electromagnetic Calorimeter6240 Time
of Flight (T+Q)448+448 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
Slide 30
DAQ System configuration
Slide 31
Some tests of power pc
Slide 32
Beam pipe and shielding Be beam pipe: 30 cm long, 63mm in
diameter, 2 layers 10-20 m Gold plating to reduce SR backgrounds
HOM power: 200W, SR: < 24 W Liquid cooling channel between walls
20 mm Tungsten shielding
Slide 33
Beam background: a serious issue 1.89 GeV @ 1 Amp All Cu
surfaces
Slide 34
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
Slide 35
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