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Decay Angular Measurement in the MEG Experiment

Decay Angular Measurement in the MEG Experiment. Shuei YAMADA International Center for Elementary Particle Physics University of Tokyo On behalf of the MEG collaboration. MEG Experiment towards SUSY GUT.

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Decay Angular Measurement in the MEG Experiment

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  1. Decay Angular Measurement in the MEG Experiment Shuei YAMADA International Center for Elementary Particle PhysicsUniversity of Tokyo On behalf of the MEG collaboration Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  2. MEG Experiment towards SUSY GUT Aim for observation of Lepton Flavor Violation: m+e+g with x102～3 improved sensitivity Compensation Coil Timing Counter COBRA Magnet Drift Chamber Paul Scherrer Institut 252cm LXe scintillation detector 262cm Surface m+ beam～0.25x108 /sec 4 Countries, ～50 Collaborators • Under construction at PSI • Start engineering run in 2005, physics run from 2006 See T.Mori’s talk for the detail: June 20, 9:30-9:55 “Search for lepton flavor violation with muons” Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  3. Contents • Physics motivations • m+ beam • MEG detector • m+e+g signature • Decay angular measurement • Summary Is MEG experiment sensitive to SUSY-GUT by measuringm+e+g decay angular? Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  4. Physics Motivation 2nd Phase : angular distribution measurement to reachSUSY-GUT using polarized m+ beam 1st Phase : m+e+g searchwith sensitivity down to 4.5x10-14 e+ angular distribution SU(5) SUSY-GUT SO(10) SUSY-GUT MSSM with nR J.Hisano et al., Phys.Lett.B391 (1997) 341 This talk Y.Kuno et al., Phys.Rev.Lett. 77 (1996) 434 Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  5. Surface Muon Beam • Muons from “Surface” of p+ production target • p+ decay at rest near the surface • 100% polarized m+ beam by nature m+ • pm29.8MeV/c • 100% polarized p+stop Primary Proton spin Pm Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  6. m+ Beamline target pE5 area @PSI Quadruple magnets Beam Transport Solenoid m+ Beamline Bending magnets MEG detector PrimaryProton Degrader m+/e+ separator • 1st phase : 0.25x108/sec (optimal for discovery sensitivity) • Capable up to 1x108/sec transport Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  7. MEG Detector • Acceptance • |cosq|<0.35 • |f|<65deg • Liquid Xe scintillator for g detector • Fast & High resolution EM calorimeter • Gradient magnetic filed e+ spectrometer See T.Mori’s talk for the detail: June 20, 9:30-9:55 “Search for lepton flavor violation with muons” Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  8. Signal and Background m g • m+e+g signature • Back to Back • Ee=Eg=52.8MeV • Backgrounds • Accidental overlap • e+from Michel decay • g from radiative decay, e+-annihilation in flight Down to ～10-14 • Radiative m+ decayDown to <10-14 e g n ? n e g n n e Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  9. Decay Angular Measurement • Able to reach SUSY-GUTby using m+ non-depolarization target such as Be, graphite • My Assumptions: • m+ beam intensity : 1.0x108/sec • beam time : 5.2x107sec (2 years) • Pm =97% (from MEGA) • m+ depolarization during transport under investigation • Measurement of depolarization needed Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  10. SUSY Model and Asymmetry • dN(m+e+g) / dcosqeＢ(m+e+g)x(1+APmcosqe)/2 • A = (|AL|2-|AR|2)/(|AL|2+|AR|2) • SU(5) SUSY-GUTA = +1 (AL0, AR=0) • SO(10) SUSY-GUTA 0 (ALAR) • MSSM with nRA = -1 (AL=0, AR0) Detector acceptance Y.Kuno et al., Phys.Rev.Lett. 77 (1996) 434 Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  11. BKG Angular Distribution • Radiative m+ decay • N(m+e+nng)∝(1+Pmcosqe) Detector acceptance Y.Kuno et al., Phys.Rev.Lett. 77 (1996) 434 Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  12. Accidental BKG suppression • e+ from Michel decay ∝ (1+Pmcosqe) • g from radiative decay ∝ (1+Pmcosqg) • Back to back : qg=qe-p ⇒Accidental BKG ∝ (1-Pm2cos2qe) • ～11% suppression @ Pm=97%, cosqe=0.35 Y.Kuno et al., Phys.Rev.D 55 (1997) 2517 Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  13. Angular Distribution • A=+1 • B (m+e+g) =10-12 Signal Backgrounds Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  14. c2 test • Poisson-distributedc2= S [2(Nobs-Nexp)+Nobsloge(Nobs/Nexp)] A=+1 B(m+e+g) = 10-12 Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  15. Sensitive region for A=+1 • Excluded region for each B(m+e+g) @ A=+1 excluded 95.4% Allowed 90.0% 68.3% Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  16. 68% C.L. Sensitive Regions • Able to distinguish A=-1, 0 or +1 by 68% C.L. for B(m+e+g)>10-12.5 A=-1 A=+1 A=0 Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  17. Allowed region for A=1,B=10-12 95.4% 90.0% 68.3% Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  18. Summary • the MEG experiment is able to reach SUSY-GUT by measuring decay angular distribution • A=-1, 0 or +1 are distinguishable for B(m+e+g)>10-12.5 with 2 years of full intensity beam • New experiment to search for m+e+g at Paul Scherrer Insitut • Start engineering run in 2005, physics run from 2006 Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  19. End of Slides Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  20. 68% C.L. Sensitive Regions • Able to distinguish A=-1, 0 or +1 by 68% C.L. for B(m+e+g)>10-12.5 A=-1 A=0 A=+1  Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  21. Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  22. Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  23. Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

  24. Sensitivity 4.5x10-14Nm=0.25x108/sec, t=2.6x107 sec W/4p=0.09, ee=0.90, eg=0.6 and esel=0.7 FWMH resolution DEe 0.8% DEg 4.5～5.0% Dqeg 19mrad Dteg 230ps Shuei YAMADA, ICEPP, University of Tokyo @ SUSY2004 Tsukuba, June 17-23, 2004

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