Satoshi MIHARA IPNS, KEK 20/Feb/20101 Satoshi MIHARA KEK-PH10

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  • Satoshi MIHARA IPNS, KEK 20/Feb/20101 Satoshi MIHARA KEK-PH10
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  • Introduction MEG COMET Other related expts at J-PARC Summary 20/Feb/2010Satoshi MIHARA KEK-PH102
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  • 20/Feb/2010Satoshi MIHARA KEK-PH10 Neutrino Mixing (confirmed) Charged Lepton Mixing (not observed yet) Sensitive to new Physics beyond the Standard Model Very Small (10 -52 ) e e ?? Soon! e e ~ B ~ mixing LFV diagram in SUSY Large top Yukawa coupling ~ LFV diagram in Standard Model e mixing e W (m /m W ) 4 3
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  • Muon discovery in 1937 Order of 10 improvement in 50 year Best limit Br( e) < 1.2x10 -11 (MEGA) Ti eTi < 7x10 -13 (SINDRUM II) Strong physics motivation Neutrino oscillation SUSY GUT 20/Feb/2010Satoshi MIHARA KEK-PH104
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  • 20/Feb/2010Satoshi MIHARA KEK-PH10 Masiero et al. JHEP03 (2004) 046 5 COMET
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  • 20/Feb/2010Satoshi MIHARA KEK-PH10 cLFV search is as important as high-energy frontier experiments (and oscillation measurements) to find a clue to understand SUSY-GUT Neutrino See-saw MEG ( e search at PSI) is expected to reach and go beyond the current limit pretty soon Need other experiment(s) to confirm it Using different physics process (with better sensitivity)! COMET (COherent Muon Electron Transittion) Submitted a proposal to J-PARC in 2008 and a CDR in 2009, and obtained Stage-1 approval in July 2009 6
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  • e decay search experiment at PSI 20/Feb/2010Satoshi MIHARA KEK-PH107
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  • 8 Aiming at observing e event with a sensitivity of ~10 -13 Normal muon decay: e Radiative muon decay: e 20/Feb/2010Satoshi MIHARA KEK-PH10
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  • 9 High intensity muon beam DC is better than plused Large acceptance of the detector system Good detector resolutions to suppress background e 180 e e ? 52.8MeV 20/Feb/2010Satoshi MIHARA KEK-PH10
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  • Muon Beam PiE5 muon beam line 1.15x10 8 + s -1 at the detector entrance at 1.8mA, 4cm Tg Photon Detector 900 liter liquid xenon 846 PMTS in the liquid Cooling with a PTR purification Positron Detector COBRA spectrometer Low-mass drift chamber High resolution timing counter 1020/Feb/2010Satoshi MIHARA KEK-PH10
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  • Proposal submitted 1999 Detector R&D and construction 1998-2007 Engineering Run end of 2007 Physics run 2008 Physics Result DAQ upgrade & problem fix during shutdown in 2009 Physics run 2009 Result Prospect 20/Feb/2010Satoshi MIHARA KEK-PH1011
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  • 20/Feb/2010Satoshi MIHARA KEK-PH1012
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  • MEG successfully started first physics data acquisition 12/Sep/2008 3x10 7 muon/sec with 2mA primary proton current on 4cm target Total live time 3.4x10 6 sec 9.4x10 13 muon stops on the target Total 139TB data on disk 13 Live time : 3.410 6 sec Total 9.410 13 muons on target t Polyester/Rohacell target Parasitic Run: 19 th May- 3 rd July ~ 7 weeks Beam Tests/Tuning (4.5 weeks) Beam Tests/Tuning (4.5 weeks) Full Run Part 1: 11 th July 31 st August ~7 weeks CEX 21 st July 31 st August (6 weeks) CEX 21 st July 31 st August (6 weeks) Full Run Part 2: 1 st September 23 rd December ~16 weeks Pre-Physics Data (~ 3 weeks) Pre-Physics Data (~ 3 weeks) Physics Data Part1 35 Days Physics Data Part1 35 Days MEG Maintenance/Repair ~ 7 Days MEG Maintenance/Repair ~ 7 Days Physics Data Part 2 43.5 Days Physics Data Part 2 43.5 Days Mini-CEX ~ 7 Days Mini-CEX ~ 7 Days TBytes MEG 2008 Run DATA Taken 139 TB 20/Feb/2010Satoshi MIHARA KEK-PH10
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  • Pre-selection and blinding Data reduction: 84% Hidden signal box on (E, t e ) Event data falling in the blind box is automatically separated (and password protected) and written to a different file from other events All analysis procedure is defined and fixed without using hidden data Analysis box is defined for the likelihood analysis 20/Feb/2010Satoshi MIHARA KEK-PH1014 Pre-selection box Analysis box Blinding box T(Gamma) - T(Positron) [nsec] E(Gamma) [MeV]
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  • 20/Feb/2010Satoshi MIHARA KEK-PH1015 and also for background study
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  • Track reconstruction with the Kalman filter technique Energy scale and resolution are evaluated by fitting the Michel spectrum at 52.8MeV Resolution function with core and tail components Core : 374keV (60%), tails: 1.06 MeV (33%) and 2.00MeV (7%) 1620/Feb/2010Satoshi MIHARA KEK-PH10
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  • Calibration using Laser data CW Boron data CEX run data Photon-Positron Relative time t e Positron time measured by TC is corrected by the time-of-flight Photon time by the time-of- flight (depth reconstruction important) RMD peak is clearly visible 40