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

2.  Introduction  MEG  COMET  Other related expts at J-PARC  Summary 20/Feb/2010Satoshi MIHARA KEK-PH102

3. 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 µ e mixing  e W  (m /m W ) 4 3

4.  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

5. 20/Feb/2010Satoshi MIHARA KEK-PH10 Masiero et al. JHEP03 (2004) 046 5 COMET

6. 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

7.   e decay search experiment at PSI 20/Feb/2010Satoshi MIHARA KEK-PH107

8. 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

9. 9  High intensity muon beam  DC is better than plused  Large acceptance of the detector system  Good detector resolutions to suppress background e   180º   e   e ? 52.8MeV 20/Feb/2010Satoshi MIHARA KEK-PH10

10.  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

11.  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

12. 20/Feb/2010Satoshi MIHARA KEK-PH1012

13.  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 : 3.4×10 6 sec Total 9.4×10 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

14.  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]

15. 20/Feb/2010Satoshi MIHARA KEK-PH1015  and also for background study

16.  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

17.  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<E<45 MeV  E dependence evaluated in CEX run data   te 148+/-17 psec  Stability better than 20psec 1720/Feb/2010Satoshi MIHARA KEK-PH10 MEGA final

18. 1820/Feb/2010Satoshi MIHARA KEK-PH10

19.  The average expected 90% CL upper limit on BR assuming no signal  1.3 x 10 -11  The 90% CL upper limit obtained for the side-band data:  (0.9 – 2.1) x 10 -11 20/Feb/2010Satoshi MIHARA KEK-PH1019

20. 2020/Feb/2010Satoshi MIHARA KEK-PH10 Expected RMD events: 40+/-8

21.  N sig < 14.7 @ 90% CL  Systematic errors included: gamma and positron E scale  Br (  e ) < 2.8x10 -11 at 90% C.L.  including systematic uncertainty on the normalization  Probability to obtain this limit given the average expected limit of 1.3x10 -11 is 5% (bad luck!)  hep-ex arXiv:0908.2594  publication soon 20/Feb/2010Satoshi MIHARA KEK-PH1021

22. 20/Feb/2010Satoshi MIHARA KEK-PH1022

23. 23  End-point is fitted to the convolution of “theoretical response function” and “Gaussian”, with three free parameters:  “E edge ”,” p ” and “Normalization”  Problem in 2008 DAQ  Too many HV trip for stable detector operation After 2-3 months of operation, DC system showed frequent HV trips. This is not due to gas aging. Due to the HV trip, e+ detection efficiency was ~1/3 of design value in average. A week point was located on PCB. New design was made to separate HV and ground line to layers. 20/Feb/2010Satoshi MIHARA KEK-PH10

24. GND +HV pcb +HV G10 isolator glue G10 isolator glue carbon frame air He / C 2 H 6 He pcb bottom layer top layer bottom layer 20/Feb/201024

25.  Intensive work on understanding problem on DCs  All DC modules were repaired before start of 2009 beam time 20/Feb/2010Satoshi MIHARA KEK-PH1025 A.M. Baldini PSI February 17° 2010 Hit map 2008 2009

26. 20/Feb/2010Satoshi MIHARA KEK-PH1026

27. 20/Feb/2010Satoshi MIHARA KEK-PH1027

28.  More stable runs than ever  Positron spectrometer  Liquid xenon photon detector  ~2 times better single event sensitivity 20/Feb/2010Satoshi MIHARA KEK-PH1028 Likelihood analysis

29. 20/Feb/2010Satoshi MIHARA KEK-PH1029 Finalize Calibrations /resolutions Final reprocessing BG Estimation Normalization Systematics Feb Final analysis Open box MarAprMayJunJul ICHEP2010 (submission) Reprocessing Next reprocessing(s) Various checks of final result Update

30.  DAQ time/Real time: 133/162 days  35/43 days in 2009 20/Feb/2010Satoshi MIHARA KEK-PH1030

31. 20/Feb/2010Satoshi MIHARA KEK-PH1031 Asymmetric Box analysis

32.  Enter in steady run conditions before proposing upgrades 20/Feb/2010Satoshi MIHARA KEK-PH1032  0.5*SES (e + eff.) and  10 * bkg (2 from Pe +, 2 from timing, 2 from e + angle)

33. -e conversion search experiment at J-PARC 20/Feb/2010Satoshi MIHARA KEK-PH1033

34.  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 20/Feb/2010Satoshi MIHARA KEK-PH1034

35. 20/Feb/2010Satoshi MIHARA KEK-PH10 1s state in a muonic atom Neutrino-less muon nuclear capture (=  -e conversion)    e  nucleus      ( A, Z )    ( A, Z  1) B(   N  e  N)   (   N  e  N)  (   N  N ' )    ( A, Z )  e   ( A, Z ) nuclear muon capture muon decay in orbit lepton flavors changes by one unit 35

36. 20/Feb/2010Satoshi MIHARA KEK-PH10  E e ~ m  -B   B  : binding energy of the 1s muonic atom  Comparison with   e(and   3e) from the view point of experimental technique  Improvement of a muon beam is possible, both in purity (no pions) and in intensity (thanks to muon collider R&D). A higher beam intensity can be taken because of no accidentals.  Potential to discriminate different models through studying the Z dependence R.Kitano, M.Koike, Y.Okada P.R. D66, 096002(2002) BackgroundChallenge   e  and   3e AccidentalDetector performance resolution, high rate  -e conversion BeamBeam background 36

37. 20/Feb/2010Satoshi MIHARA KEK-PH10  Photonic and non-photonic (SUSY) diagrams photonicnon-photonic   e  yes (on-shell)no  -e conversion yes (off-shell)yes 37

38.  V. Cirigliano et al. PRL 93, 231802 (04)  R=B(  e)/B(  e)  RPV-SUSY  R >> 10 -2  LRSM (Left-Right Symmetric Model)  R~O(1)  Important to measure R to extract m 0 from  0 20/Feb/2010Satoshi MIHARA KEK-PH10 RPV-SUSY LRSM 38

39. YearMuon sourceTargetUpper bound 1952Cosmic raysCu, Sn4×10 −2 1955Nevis cycl.Cu5×10 −4 1961Berkeley synchroc.Cu4×10 −6 1961-62CERN synchroc.Cu2.2×10 −7 1972Virginia SREL synchroc. Cu1.6×10 −8 1977SINS7×10 −11 1984TRIUMFPb Ti 4.9×10 −10 4.6×10 −12 1992PSIPb4.6×10 −11 1993-97(only in conference proc.) Ti6.1×10 −13 2006Au7×10 −13 20/Feb/2010Satoshi MIHARA KEK-PH1039

40. 20/Feb/2010Satoshi MIHARA KEK-PH10 SINDRUM-II used a continuous muon beam from the PSI cyclotron. To eliminate beam related background from a beam, a beam veto counter was placed. Published Results 40

41. 20/Feb/2010Satoshi MIHARA KEK-PH10 Fermilab Accelerators  The mu2e Experiment at Fermilab.  Proposal has been submitted.  CD-0  After the Tevatron shut-down  uses the antiproton accumulator ring  the debuncher ring to manipulate proton beam bunches 41

42. 20/Feb/2010Satoshi MIHARA KEK-PH1042

43. 23/Oct/2009ILC Seminar 2009  Backgrounds  Beam Pion Capture   - +(A,Z)  (A,Z-1)*  + (A,Z-1)   e + e -  Prompt timing  good Extinction!   - decay-in-flight, e - scattering, neutron streaming  Requirements from the experiment  Pulsed  High purity  Intense and high repetition rate nuclei  Muon Capture(MC) Muon Decay in Orbit (MDO) SIGNAL

44. 23/Oct/2009ILC Seminar 2009  Proton beam structure for the mu-e conversion search  100nsec bunch width, 1.1sec bunch-bunch spacing  8GeV to suppress anti-proton background  < 10 11 proton/bunch, limited by the detector performance  Repetition rate as high as possible within tolerable CR background  Extinction  Residual protons in between the pulses should be < 10 -9 1.17s (584ns x 2) 0.7 second beam spill 1.5 second accelerator cycle 100ns N bg = NP R ext x Y  /P x A  x P  x A NP x R ext x Y  /P x A  x P  x A NP : total # of protons (~10 21 ) NP : total # of protons (~10 21 ) R ext : Extinction Ratio (10 -9 ) R ext : Extinction Ratio (10 -9 ) Y  /P :  yield per proton (0.015) Y  /P :  yield per proton (0.015) A  :  acceptance (1.5 x 10 -6 ) A  :  acceptance (1.5 x 10 -6 ) P  : Probability of  from  (3.5x10 -5 ) P  : Probability of  from  (3.5x10 -5 ) A : detector acceptance (0.18) A : detector acceptance (0.18) BR=10 -16, N bg < 0.12  Extinction < 10 -9

45. 23/Oct/2009ILC Seminar 2009  RCS: h=2 with one empty bucket  MR:h=8(9) with 4(3) empty buckets  Bunched slow extraction  Slow extraction with RF cavity ON Realization of an empty bucket in RCS by using the chopper in Linac Simple solution No need of hardware modification Heavier heat load in the scraper Possible leakage of chopped beam in empty buckets Simple solution No need of hardware modification Heavier heat load in the scraper Possible leakage of chopped beam in empty buckets

46. 23/Oct/2009ILC Seminar 2009  Single event sensitivity  N  is a number of stopping muons in the muon stopping target. It is 2.0x10 18 muons.  f cap is a fraction of muon capture, which is 0.6 for aluminum.  A e is the detector acceptance, which is 0.031. total protons muon yield per proton muon stopping efficiency 8.5x10 20 0.0035 0.66 # of stopped muons2.0x10 18 Single event sensitivity 2.6 x 10 -17 Single event sensitivity 2.6 x 10 -17 90% C.L. upper limit 6.0 x 10 -17 90% C.L. upper limit 6.0 x 10 -17

47. 23/Oct/2009ILC Seminar 2009  Background rejection is the most important in searches for rare decays.  Types of backgrounds for  - +N  e - +N are, Intrinsic backgrounds originate from muons stopping in the muon stopping target. muon decay in orbit radiative muon capture muon capture with particle emission Beam-related backgrounds caused by beam particles, such as electrons, pions, muons, and anti-protons in a beam radiative pion capture muon decay in flight pion decay in flight beam electrons neutron induced antiproton induced Other backgrounds caused by cosmic rays cosmic-ray induced (pattern recognition error)

48. 23/Oct/2009ILC Seminar 2009  Muon Decay in Orbit  Electron spectrum from muon decay in orbit  Response function of the spectrometer included.  0.05 events in the signal region of 104.0 - 105.2 MeV (uncorrected).  Radiative Muon Capture with Photon Conversion  Max photon energy 102.5 MeV  < 0.001 events  Muon Capture with Neutron Emission  Muon Capture with Charged Particle Emission  <0.001 events for both. Energy spectrum of electrons from decays in orbit in a muonic atom of aluminum, as a function of electron energy. The vertical axis shows the effective branching ratio of -e conversion.

49. 23/Oct/2009ILC Seminar 2009 a number of events for 1.1 x10 18 stopped muons. <0.05 events

50. 23/Oct/2009ILC Seminar 2009 Rejection of beam related (prompt) backgrounds can be done by a combination of the following components. Momentum Selection at the Muon Transport (p  < 75 MeV/c) Timing Cut and Beam Extinction (10 -9 ) Electron Energy Cut (104.0 - 105.2 MeV uncorrected) Electron Transverse Momentum Cut (p T > 52 MeV/c) Beam Channel Length (pion decay)

51. 23/Oct/2009ILC Seminar 2009  Radiative Pion Capture  pion prod. rate : 1x10 -5  pion survival : 2x10 -3  E e >104 MeV with conversion : 6.3x10 -6  beam extinction : 10 -9  0.12 events at 10 -16.  Muon Decay in Flight  p  >77 MeV/c : 2x10 -4 /proton  muon decay prob. : 3x10 -2  E e >104 MeV & p t > 52MeV/c : <10 -8  beam extinction : 10 -9  total is 0.02 events at 10 -16.  Pion Decay in Flight    e branching ratio : 10 -4  p  >60MeV/c to make E e >104MeV:5x10 -6 / proton  E e >104 MeV & p t > 52MeV/c : 5x10 -6  beam extinction : 10 -9  <0.001 events at 10 -16  Beam Electrons  p e >100 MeV/c : 10 -8 /proton  scat. prob. : 10 -5  beam extinction : 10 -9  0.08 events at 10 -16  Neutron induced  neutrons through beamline.  E n >100 MeV : 3x10 -7 /proton  E e >100 MeV : 10 -7  beam extinction : 10 -9  0.024 events at 10 -16.  Antiproton induced  eliminate high-energy antiprotons by curved solenoid.  absorb low-energy antiprotons by 120 m beryllium foil placed in the middle of beamline.  eliminate backgrounds from antiproton annihilation above.  0.007 events at 10 -16.  Cosmic ray Background  eliminate by passive and active shields.  10 -4 veto inefficiency assumed.  0.04 events for 2x10 7 sec (a duty factor 0.2) 8x10 20 protons

52. 23/Oct/2009ILC Seminar 2009 BackgroundEventsComments Radiative Pion Capture0.05 Beam Electrons<0.1MC stat limited Muon Decay in Flight<0.0002 Pion Decay in Flight<0.0001 Neutron Induced0.024For high E n Delayed-Pion Radiative Capture0.002 Anti-proton Induced0.007For 8 GeV p Muon Decay in Orbit0.15 Radiative Muon Capture<0.001 Muon Capture with n Emission<0.001 Muon Capture with Charged Part. Emission<0.001 Cosmic-Ray Muons0.002 Electrons from Cosmic-Ray Muons0.002 Total0.34 Assuming proton beam extinction < 10 -9

53.  R&D work in progress  Detector, SC magnet, Proton extinction 20/Feb/2010Satoshi MIHARA KEK-PH1053 Funding starting 1st year design & order of SC wires 2nd year 3rd year 4th year 5th yearengineering run 6th yearphysics run

54. 20/Feb/2010Satoshi MIHARA KEK-PH1054

55.  Visit M.Aoki’s JPS talk 20/Feb/2010Satoshi MIHARA KEK-PH1055

56.  Not cLFV search, but closely related in physics motivation  g-2 measurement at FNAL using the BNL g-2 ring  Use very cold muons and precisely controlled magnetic field  Smaller size detector for lower muon momentum than the “magic” momentum  Muon EDM measurement? 20/Feb/2010Satoshi MIHARA KEK-PH1056 Proton beam (3 GeV, 1MW ) Laser Muon Linac (300 MeV/c) Surface Muon (~30 MeV, 4x10 8 /s) Ultra Cold Muon Beam (  + 10 6 /sec) Muonium < 70 cm Injection !

57.  cLFV search experiments using muons  MEG  COMET  DeeME and g-2 at J-PARC MLF 20/Feb/2010Satoshi MIHARA KEK-PH1057