BESIII Present barrel TOF The option of barrel TOF is determined after many discussions in June, 2005. Two layers of scintillator will be used for barrel. Barrel TOF Endcap TOF CsI Calorimeter Drift Chamber
BESIII Fig. Assembly of barrel TOF. Barrel TOF alignment Fig. BTOF side view. To save space, the base of PMT housing is 6-sides-shaped and the inner and outer layer is across. It has four screws to connect the scin.
BESIII ItemBarrel time reso. Endcap time reso. Intrinsic time reso. of one TOF layer for 1 GeV muon 80~90 ps80 ps Uncertainty from electronics25 ps Uncertainty from bunch length 15 mm ， 35 ps Uncertainty from bunch time~20 ps Uncertainty from Z position5 mm,25 ps10 mm,50 ps Resolution of expected time of flight30 ps Total time reso, one layer of TOF for 1 GeV muon 100~110 ps110~120 ps Total time reso, double layer of TOF for 1 GeV muon 90 ps Analysis of Time reso. Non TOF ~60ps
BESIII Why two layers? Time reso. For Kaon and pion is worse 20% than muon in experiences. Time reso. Of two layers totally is from 100ps to 110ps for kaon and pion. That time reso. Can separate kaon/pion of 0.9GeV in the middle of barrel. ContriburionTime reso. For 1GeV Muon Time reso. For Kaon/pion Non TOF60ps One layer of scin. Intrinsic 80-90ps One layer of Scin. Totally 100-110ps110ps-130ps Two layers, Totally 80-90ps100ps-110ps Capability of separation of Kaon and Pion
BESIII 2. Physics targets for PID and our space limits
BESIII K/πmomentum on BESIII BEPCII: 2.0~4.2GeV BESIII: Charm physics:J/Psi, Psi ’, Psi ’’ Tau Physics K/π momentum: almost all<1.5GeV K/π seperation: 1.2GeV is enough Present TOF: 0.9GeV(2sigma,95%) Next target Momentum distribution for hadrons at J/psi
BESIII Experimental Searching for D 0 D 0 Mixing (From He Kanglin ) Big challenge to PID (Kπchannel) Main backgrounds come from the double miss-PID Searching in semi-leptonic decay modes are experimental difficulty with 2 missing neutrino (hard to reduce background contribution to 10 -4 ) Monte Carlo study with different PID (TOF resolution)
BESIII Target analysis for MRPC To get 1.2GeV separation of K/pi, totally time reso. <80ps Non-TOF is 60ps, TOF <60ps, Plastic scin. Can ’ t give so good time. MRPC may be OK. To cover dead area of MRPC, overlap of two layers of MRPC is needed. To reduced electronics, MRPC should be long strip and readout by two ends. Long-strip MRPC needs much more studies.
BESIII III. 4 gaps, 0.3mm/gap HV:10kV/mm Preamp: not say GAS: 85% C2H2F4 5% iso- C4H10 10%SF6 ， 达到的时间分辨为 75ps
BESIII MRPC option bakelite as the resis. plate Structure: Resi. Plate: bakelite gaps: 6; Chamber: 8cm(W)X190cm(L) gas ： 90%Freon, 5%iso-butane, 5%SF6 Preamp ： Star Signal pulse HV: 16kV/1.2mm) Readoud pad:3X6cm Rise time:~2ns Time Reso.:70 ～ 110ps The results for a MRPC sample where the fish-line is rolled in longitude direction
BESIII 钓鱼线竖绕板室的初步实验结果（吴金杰） Structure: Resi. Plate: bakelite gaps: 6; Chamber: 8cm(W)X190cm(L) gas ： 90%Freon, 5%iso-butane, 5%SF6 Preamp ： Star Signal pulse HV: 16kV/1.2mm) Readoud pad:3X6cm Rise time:~2ns Time Reso.:~110ps Reasons: gap not well
BESIII Cherenkov detectors NamePrincipleRange of PID readout 美国 SLAC Babar － DIRC  Quartz + long bar + Water tank + PMT ～ 4GeV11000 PMT ， 日本 KEK BELLE － ACC  ACC, Threshold type ～ 3.5GeV 2000 Fine-Mesh PMT 美国 CLEO-III RICH LiF as the radiator,TEA gas to convert photon-electron, MWPC to detect the ring of cherenkov ～ 2.8GeV 230,000 channels electronics CERN LHC-b RICH  Two RICHs. RICH1: 5cm thick ACC and 95cm thick C 4 F 10 as radiator;RICH2: 180cm thick CF 4 as radiator ～ 150GeV Hybrid PhotoDiode, Much space CERN LEP DELPHI RICH  Gas of C 5 F 12 and liguit of C 6 F 14, as radiator, ~25GeVgas photodetector + MWPC to readout
BESIII Internally reflecting cherenkov detector Using internally reflecting cherenkov light Parameters to know: track direction Cherenkov light(x,y), or (theta, phi) Transmitting time:
BESIII 3 options (refers to Honscheid,Ohshima,Vavra,) CCT(Cherenkov Correlated Timing ) 1D Timing only a) Time is related to cherenkov angle
BESIII CCT Its principle is to measure the time of the cerenkov light to separate particles. We did simulations. There are about 10 PEs for 2inches PMT with QE of 20%. reso. Transit time spread of PMT: Line-focus type PMT, 250ps (xp2020) Fine-mesh type PMT, 180ps (R5924) Micro-Channel-Plate type PMT, 50ps (R2809U)
BESIII Potential of CCT: MCP-PMT to give good time reso. Refer to:Jochen Schwiening, SLAC T. Ohshima, Nagoya Univ.
BESIII Comparison of K/ sep. TOF+TOF TOF+CCT Fig. K / separation for Double TOF Fig. K / separation for TOF+CCT
BESIII TOP: Time of Propagation Principle: only Φ c andθ c can determine cherenkov angle. TOP and Φ can deduce them. Quartz bar’s sides are vertical and conserve the Φ c. Quartz lightguide is needed to ensure the light direction out of quartz bar Fucussing Mirror: fucussing the parrel light because of the thickness of quartz bar. Photon detector is placed opposite of mirror. To deduce dead area, the detection end will be placed in opposite ends for adjacent counters
BESIII Uncertainties of TOP Chromatic error. 5 ‰ 。 Uncertainty of Φc. Mirror’s resolution and PMT position resolution, can be 9mrad. Time spread of PMT Start time resolution Thickness of quartz bar. High speed particle transmit quartz bar (20mm) needs about 66ps. But when particle inclined transmits, the uncertainty will be reduced because particle transit time and light transit time lessen it. Position of injected particle. ~2mm ， ~10ps Photon electron number Cherenkov ring by Y.Enari Using TOP. Particle 4GeVπ ， position:1m. 2GeVπ ， position:0.02m 和 1m 处. TOP resolution VS Φ.By Ohshima.
BESIII TOP: Candidate of Super Belle Refer to Peter Krizan, Super B factory workshop, Frascati, 2006
BESIII TOP: For BESIII, 1.2 GeV is enough, 1.5 GeV is very good. Refer to Noriaki Sato, 2005, hawaii
BESIII Focusing DIRC Measure the time and 2dimension position It uses APD or MCP PMT to measure the time and position of Cerenkov light from Quartz. No big imaging circles and so no much space is needed. The money is saved because of smaller quantity of PMT.
BESIII Candidate of Babar ’ s next plan From Vavra, Hawaii workshop
BESIII 5. Summary 1.2GeV K/Pi separation is needed for BESIII physics. Now it is only 0.9GeV. Upgrade is nessesary. <60ps of Long-strip MRPC is OK to give 1.2GeV separation. Experiments is under way. 60ps is not easy. CCT has good potential for the upgrade. It is simple with MCP-PMT of good time reso. TOP can give over 1.5GeV separation of K/pi. Focusing DIRC needs more space, impossible for BESIII