Status of BESIII INSTR 08 Conference February 28, 2008 BINP, Novosibirsk Boxiang Yu IHEP Beijing 1
The Structure of BESIII Detector BESIII assembly and installation have been finished. Cosmic-ray tests are underway Magnet yoke SC magnet, 1 T RPC TOF Be beam pipe MDC, 120 mm Cs. I(Tl) calorimeter, 2. 5 %@1 Ge. V 2
Drift chamber • To measure the momentum of charged particles by its bended curvature in a magnetic field R inner: 63 mm ; R outer: 810 mm Length (out. ): 2582 mm Inner cylinder: 1. 2 mm Carbon fiber Outer cylinder: 11. 5 mm CF with 8 windows Sense wire : 25 micron gold-plated tungsten wire --- 7, 000 Layers (Sense wire ): 43 Field wire: 110 micron gold-plated Aluminum wire--- 22000 Gas: He + C 3 H 8 (60/40) Cell: inner chamber --- 6 mm outer chamber --- 8. 1 mm Expected performance 3
Mechanical structure Preamplifier Installation Thresholds Installation HV cables installation 4
Cosmic-ray tests setting 8 plastic scintillator to give trigger. Result of cosmic-ray tests 5
The chamber installed 6
Preliminary result of cosmic ray test Result of Cosmic ray test with TOF B 2 B trigger after chamber installation Time histograms T distribution of one layer Dead chanel Time hitmap of 7, 000 sense wires T hitmap of 43 layers 7
RESULT l. The MDC cosmic ray data had been obtained by online system. l. Electronics calibration can work on DAQ system l. T and Q distribution is OK. T and Q hit map with correct shape. One dead channel. We have repaired it. n More detail study needed Electronics noise Calibration With TOF b 2 b triger Q hitmap of 7, 000 wires Q distribution of one layer 8
BESIII Cs. I(Tl) crystal calorimeter • • To measure the energy of electromagnetic particles Barrel: 5280 crystals，Endcap: 960 crystals Crystal: (5. 2 x 5. 2 – 6. 4 x 6. 4) x 28 cm 3 Readout: 13, 000 Photodiodes, 1 cm 2 cm, Energy range： 20 Me. V – 2 Ge. V position resolution: 6 mm@1 Ge. V Tiled angle: theta ~ 1 -3 o, phi ~ 1. 5 o Energy resolution: 2. 5% @1 Ge. V Structure of EMC 9
Cs. I(Tl) Crystal detector module n n n 2 Photodiodes + 2 Preamplifiers+1 amplifier Photodiode (PD): Hamamatsu S 2744 -08 Preamplifier noise: < 1100 ENC (~220 kev) Shaping time of amplifier: 1μs Structure of module 10
Assembly of the Module ( Lab ) Relative light output test; Dimension test; Radiation hardness test; Crystal Re. Num Pair up Drill 4 holes Pre. Amp test Pre. Amp quality control 2 PDs glued with lucite Ready for construction quality control Cosmic ray test PD Setup to get Crystal module Dark current and capacitance test; Aging test; photo sensitive test; Fix bottom plate Glued together quality control 11
Crystal production and tests France Sanit -Gobain Shanghai Institute of Ceramics Beijing Hamamatsu Total Ordered 3, 000 1, 920 1, 320 6, 240 Replaced 91 316 7 486 Reasons of replaced crystals: radiation hardness, uniformity, dimension. Relative light output Uniformity of crystal 12 Radiation damage test Requirement: < 20% decrease of light output after 1000 rads
Beam tests (6 x 6 crystal array) ADC X position Reasons (Energy resolution>2. 5%): Bad momentum resolution of test beam; High background of experiment place; 13
Assembly of Super Module Two rows 88 detector modules first put in a large container, then one Al L plate be used to hang up crystal with the steel gird. cooling system, read out cable, LED fiber system are put on. Al L plate installation Cable instalation Super module installation Super module completed 14
Installation of EMC Barrel EMC installed installing Barrel EMC Total weight : 54 ton Endcap EMC installed Inner of barrel No gap between crystals 15
Preliminary result of cosmic ray test l. The EMC cosmic ray data had been obtained by online system. l. Electronics calibration can work on DAQ system l. Q distribution is OK. The hit map with correct shape. No dead channel. n More detail study needed Q distribution of one crystal Noise Calibration result of east barrel 16 Hitmap of east barrel
PID: Time-Of-Flight counters • To measure the flight time of particles in order to identify them: m=P/(L/t) Barrel TOF consists of tow scintillator rings Barrel TOF Endcap TOF Two layers structure improves the k/π separation. Module consist of: one High quality plastic scintillator: 2. 4 m long, 5 cm thick 17 Tow PMTs, tow preamplifier
Scintillator tests • Tests on scintillator bars The top and bottom 2 scintillator bars to give trigger. – Most Attenuation lengths are over 4 m. • Matching criteria for scintillator and PMT: Fig. Cosmic ray tests on scintillator Attenuation length Average: 4. 8 m – (Scintillator light output) X (PMT SKB) is similar Fig. Attenuation length and relative light output of Scintillator, ALL are 18 OK
Beam test at IHEP pions 104± 11 ps protons 70± 2 ps electrons 94± 3 ps Result: Time resolution from beam test of prototype（including scintillator, PMT, preamp, electronics, cable). Time difference of two TOF layers: no errors from reference 19 time (To) or position.
Barrel TOF installation Procedures: – Pad PE layers on DC – Installing three assembling ring – The position determined according to the sizes – Installing scin. Bar and fixing – fixing the scintillator by 3 M fiber tape – Get off the screws and assembly ring Fig. Assembly rings Fig. Fixing by screw Fig. Installing scin. bar Fig. Bundling by fiber 20 tape
Preliminary result Cosmic Ray Tests Cosmic ray signal • Cosmic ray signal of Each channel is observed by O. S. firstly. • The TOF cosmic ray data had been obtained By online system. – Q distribution is OK. – The hit map with correct shape. – There are two dead channels in east end. We have repaired them. Q distribution The hitmap 21
Electronics calibration • Electronics calibration can work on DAQ system. • The Q correction is OK. – Q needs quadratic correction for nonlinearity. – The correction result is consistent with that in Lab. Fig. Q quadratic correction. • T’s resolution is OK. 22 Fig. T’s RMS is only 16 ps by calibration signal.
• • • m system : RPC 9 layers, 2, 000 m 2 Special bakelite plate with linseed oil 33 mm strips, 10, 000 channels Noise less than 0. 1 Hz/cm 2 One dimension read-out strips; Structure of μsystem Producing RPC 23
(RPC module) • Total of 64 endcap modules, 72 barrel modules; • HV voltage: 8000 V; • One module contains two RPC layers and one readout layer. an endcap module Without linseed oil, the chambers operated as good as the ones with linseed oil. 24
Test results after installation Module size: 3800 mm*1640 mm Strip length: 3800 mm Strip width: 33 mm Average strip efficiency: 99% Spatial resolution: 14. 2 mm 25
MUON system cosmic ray test The hit map with correct shape. More detail study needed 26
Super-conducting magnet installation specification : 1 T@3400 A wiring transportation Thermal insulation assembly installation 27
Field mapping Computer controlled 3 D mapping machine is used for field mapping. Field measuring accuracy < 0. 25%. Measure ~90, 000 points with 0. 5 mm position accuracy. Mapping device The result of Field map The magnet reached super-conducting status and 1 T magnetic field at 3364 A. 28 Field mapping with SCQ completed
Trigger system l Information from sub-detector electronics is fed to sub-detector trigger system via fiber optical cables. l All trigger logic stored in FPGA chips are programmable. l The trigger latency is designed to be 6. 4 μs. Trigger system runs smoothly in cosmicray tests. Total： 4× 9 UVME Crates 1× 6 UVME Crate 1×NIM Crate Hardware structure of trigger system 29
DAQ & online software Expected performance §Trigger rate: 4 KHz § Event Size: 12 KBytes § Bandwidth: 48 MByte/sec l. The whole DAQ system tested to 8 KHz for the event size of 12 Kb, a factor of two safety margin. § Dead time: < 5% 1000 * BESII DAQ system Figure of Cosmic-ray tests Event display software runs smoothly The structure of DAQ system All subsystems run smoothly
Monte Carlo simulation • • • GEANT 4 based simulation framework completed Geometry, material and detector response completed Real detector response including 3 D magnetic field, noise, trigger, bunch size etc completed All tested by reconstructed physics events Many generators, some are new for tau-charm physics Stable operation, large data sample generated 31
Event reconstruction and calibration • Gaudi based framework completed • Sub-detector reconstruction and calibration almost completed: • • Kalman-filter based track fitting Basic calibration algorithm established No-bias Event reconstruction Resolution in agreement with specification Timing zero can be reconstructed c 0: 126 Me. V Secondary vertex can be reconstructed Online event filter Stable operation for physics studies Inclusive spectrum in (2 S) decays c 1: 170 Me. V c 2: 259 Me. V 32
BESIII is ready! 33
Schedule • 2/2003: Official approval of the project • 7/2004: BESII detector shutdown • 5/2005: Magnet yoke & muon chamber installation • 9/2006: Super-conducting magnet cool down • 6/2007: Magnetic field mapping starts • 8/2007: EMC installation starts • 10/2007: MDC/TOF installation starts • 1/2008: Cosmic-ray tests • 3/2008: BESIII detector in place • 6/2008: Start data taking 34
USA (2) University of Hawaii University of Washington Europe (4) GSI, Germany University of Bochum, Germany University of Giessen, Germany JINR, Dubna, Russia China (22) IHEP, CCAST, GUCAS， Univ. of Sci. and Tech. of China Shandong Univ. , Zhejiang Univ. Huazhong Normal Univ. , Wuhan Univ. Zhengzhou Univ. , Henan Normal Univ. Peking Univ. , Tsinghua Univ. , Zhongshan Univ. , Nankai Univ. Shanxi Univ. , Sichuan Univ Hunan Univ. , Liaoning Univ. Nanjing Univ. , Nanjing Normal Univ. Guangxi Normal Univ. , Guangxi Univ. Japan (1) Tokyo University 35
Summary • BESIII assembly and installation have been finished, cosmic-ray tests are underway, physics run will start this summer • Physics and software preparation are underway • We are excited about the great physics opportunities of BESIII and welcome new collaborators 36
The end Thank you! 37
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