BES-III TOF (Endcap) ??

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BES-III TOF (Endcap) ??

• ??????????????
• ????????TOF???
• ?????????
• ????

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Time resolution for BESIII/TOF.
Item Barrel time reso. Endcap time reso.
Intrinsic time reso. of one TOF layer for 1 GeV muon 8090 ps 80 ps
Uncertainty from electronics 25 ps 25 ps
Uncertainty from bunch length 15 mm,35 ps 15 mm,35 ps
Uncertainty from bunch time 20 ps 20 ps
Uncertainty from Z position 5 mm,25 ps 10 mm,50 ps
Resolution of expected time of flight 30 ps 30 ps
Total time reso, one layer of TOF for 1 GeV 100110 ps 110120 ps
Total time reso, double layer of TOF for 1 GeV 90 ps
Non TOF 60ps
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• ??????????PMT??
• ??2003-2006?
• 1)???????
• 2)???????
• 3)????

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Configuration
800
966
1676
The Endcap TOF (ETOF)of Beijing
Spectrometer(BESIII) is consisted of 248 pieces
of trapezoidal scintillator . Its main physics
goal is to realize the separation at momentum
up to 1Gev/c, and the intrinsic time resolution
reach to 80ps.
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???? ???
1.R5924 PMT-base??????Base?????????PMT????,?????
??????????,????????,?????????????
2.PMT????????????Fine Mesh PMT
?????,??????????????????????????PMT??(???)?????(
????3) PMT?????????? 3.??????????????????????
??????,???????50ps??????????????????,?????????????
??,??PMT??????????????????????????????2-4?????????
????? 4.??????????????,?????
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PMT ??
Base??????? ??PMT????,??????, ?????????,????????,
??????????????
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PMT????
?????? lt1.5ns, ????4.0ns .??CHERENKOV?????,??R592
4??????? ?????????? FWHM460ps.
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PMT Gain Measurement
????3
The gain measured of R5924 PMT with three methods
SPE method With LSO crystal With XP2262 PMT From Hamamashu
PMT01 2107 0.53 3.8 107 3.0 107
PMT02 1.45107 N/A 3.2 107 2.3 107
PMT03 2.7 107 1.0 8.2 107 4.7 107
PMT04 N/A 0.49 N/A 2.4 107
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The gain in magnetic field
The spectrum of pulse magnitude measured with the
LSO crystal in magnetic field at IHEP
The gain decrease in 48 times at 1T and the
angle of zero degree
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PMT measured for 1T at KEK by Tokyo Univ.
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Cosmic test
The energy deposit in ETOF for MIP
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??????????
?????????????????????????,?????????,???????,?
???????????????????????,?????BC404???,??50mm,????
??????. ??????1.5GeV??????????????
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Test Results(1)
The primary results show that the time resolution
of ETOF(BC408) with Tyvek paper wrapped is
between 75-90ps.
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Test Results (2)
The beam tested results show that the time
resolution of ETOF(BC404) with ESR film wrapped
is between lt80ps.
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???? ???????
1.?????????????????????,???????,?PMT???????????
2)??????????????PMT????????,PMT???????,??????????
?? 3)???????????
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The Layout of ETOF scintillator bar
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?????
????????480mm ???431mm,??????????ETOF???????
???????????????
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???????

• BC404,98?
• ????,??????????
• ?????????
• ??,????????

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PMT5924???

• R5924,113?
• ??????
• ?????????(????),????5105 ?5106??????
• ????PMT?????
• ??????????
• ??,????

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Batch Test of the PMT Gain
The gain curve of R5924/PMT under different
high voltages.
The voltages at which the gain reaches 5105 and
5106
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PMT??????????

• 120?PMT????????????
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• ???
• ?????PMT
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• ?????

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96????????

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???? ????
1)??????????PMT,????????????,?????,?????? 2)???
??????18???????,????,???????18??????????
3)?????????? TOF???????????? ???????????? ???,???
???,?? ??,?
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ETOF ????
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???
ETOF???????
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??
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Cabling Grounding
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?????????

• ????????,????????

(??EMC????????)
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Fiber ConnectingCooperated with Hawaii University
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ETOF????
07.12-08.2??????????????? ????,???????10mV
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End cap single
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Q measurement
Total 4 dead Channels! Pre-amp?
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Q mean
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Time measurement
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T sigma after Q-T
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??

• ETOF ???????????
• ETOF ??????BESIII??
• ETOF ???????????,???????????
• ???????????,?????????????????,????????????,????
  ???????!

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• ??
• ?????????,
• ??????BESIII ?????????!
• ????????????!