1、液體Xe用光電子増倍管低溫性能評価 東大素粒子A , 高研B , 早大理工総研C春山富義B, 大谷航A, 小曽根健嗣A, 菊池順C, 道家忠義C三原智A, 森俊則A, 山口敦史C東京大學(xué)素粒子物理國際研究森研究室修士年久松康子久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Cryogenic performance test of a photomultiplier for the liquid Xe calorimeterAbstractAbout MEG ExperimentPMT for MEG photon detectorWorks on Final Design of PMTPM

2、T test at Univ. of TokyoSummary久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)MEG Experiment + e+ beyond SMSUSY-GUT promisingMEGA(1999)Br 1.2*10-11MEGBr 10-14Approved by Paul Scherrer InstitutUsing intense muon beam PSI1*108/secStart of Physics Run : 2006 52.8 MeV52.8 MeV久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Photomultiplier (PMT)High

3、ly sensitive light sensor often used in high energy physics experimentsElectron tube device which converts light into a measurable electric currentPhotoelectric effectphotonElectrode and dynodee-photocathodeMeasureable electric pulse久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)e-e-Electron collection and multiplication

4、MEG Liq. Xe detectorDetect scintillation light with 800 Liter liq.Xe and with 830 PMTs 久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)PMTLiq.XePMT 165K (Liq.Xe temp.) 久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)photocathodee-photonTemperaturesurface resistanceQuantum EfficiencySignal OutputNeed to reduce surface resistance of photocathodeP

5、MT 165K under high rate B.G.First version PMTs output deteriorates under high rate B.G. Related to the characteristics of photocathode at the low temperature久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)signal outputB.G. ONtimeexpectedPMT will be exposed to large amount of light produced by high rate background radiatio

6、nPMT output needs to be stable under high rate B.G.signal output20%B.G. ON 20 minPMTBackgroundsignalPMTsignalBackgroundsignalDevelopment of PMT for MEG ExperimentFirst Ver.Second Ver.Final Ver.PhotocathodeRb-Cs-SbK-Cs-SbK-Cs-SbMaterial to reduce surface RMn layerAl Strip Al Strip (doubled)Q.E. 165K5

7、%?久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Efficient Q.E. 165K (reduction of surface resistance)Stable output under high rate backgroundHow much has Q.E. improved?Will PMT survive the high rate background environment 165K ?PMT Test Univ. of Tokyo Liq.Xe chamberPulse tube refrigeratorLiq.N2久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)L

8、iq. XeLiq.N2 cooling pipeVacuume AISIN PR121Compressor : TAC 101JCooling Power : 25W 165KCold head temperature monitor : Pt100Platinum Thin Film ResistanceCold head temperature control :MINCO Thermofoil Heater 65mmPMT Test Set up Q.E. measurement55mm55mmObserve 5.5MeV alpha eventGain calibration usi

9、ng LEDGain :106久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)241Am (alpha source)LEDReference PMTPMTHow much has Q.E. improved?46mm33mmQ.E. measurement久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Q.E. ratioPMT Test Set up Rate dependence test久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Will PMT survive the high B.G. environment at 165K?PMT BackgroundsignalHow

10、 to simulate High rate B.G. ?LEDPulse tube refrigeratorLED241Am (alpha source)Liq. XePMT Rate Dependence Test Procedure241AmLEDPMT241Am (alpha source)LEDLiq.XealphaObserve 5.5MeV alpha event, 200Hz LED simulate the high rate backgroundpulse height:40007200 p.e./eventpulse shape: 10nsecrate: 500Hz 10

11、KHz久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Max. B.G. Level in MEG experiment1.3*107p.e./sec c.f. First Version PMT久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)timesignal output20%B.G. ON 20 minPMT for MEG final version Rate Dependence Liq. XePMT was tested under various background environment by changing the rate of LED expectedsigna

12、l outputtimeB.G. ON20minThe output from final version PMT is stable under the high rate background environmentSummaryPMT for MEG experiment has been developed.Able to operate under 165K, Liq.Xe temp.Cryogenic performance of Final Version PMT is tested liq.Xe.PMT has efficient Q.E. even at 165K PMT o

13、utput at 165K is stable under the high rate background environment. 久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)以下予備PMT for MEG Experiment Metal Cover SUSAble to withstand pressure up to 0.3MPaPhotocathode : BialkaliSensitive to VUVWindow : Quartz glassKovar GlassKovar Metal久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Flow sheet PMT Test

14、 Facility久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)PMT Test facility Univ. of TokyoXe tankLiq.Xe chamberPurification systemPMT stability, DAQ ProcedureDAQ started after all chamber components become low temperatureTrigger : alpha self triggerDAQ Procedure : Pedestal RunGain Calibrationalpha run久松康子日本物理學(xué)會2004年秋季大會高知大

15、學(xué)muon radiative decayGamma from positron annihilationNeutrons from proton beam p 0 n 0 p n neutrons from pions CEX reaction (calibration run) 5583129MeV energy spectrumBG level 2A 106gain (107p.e./sec)Major Background for PMT52.8 MeV52.8 MeVc.f. muegamma event久松康子2004年度低溫工學(xué)超伝導(dǎo)學(xué)會八戸工業(yè)大學(xué)Condition and ProcedureGain 1*106Trigger: alpha self trigger (veto by LED driver pulse) ProcedurePedestal Run & Gain calibration using LED Alpha Run