1. 17/May/2011Pisa Seminar 2011 mu-e conversion search experiment COMET at J-PARC Satoshi MIHARA Satoshi.mihara@kek.jp KEK, Japan

2. 17/May/2011Pisa Seminar 2011 Outline J-PARC Introduction COMET at J-PARC –Proton/Muon beam at J-PARC –Detector –Sensitivity and Background –(R&D Status) –Schedule and Cost Summary

3. 3 17/May/2011Pisa Seminar 2011 Tohoku Earthquakes and Tsunami Japan has been deformed by the earthquakes of Mar 2011 The earth itself too –daily rotation speed changed and day length has been shortened by 1.8μsec Tsunami was induced by the quakes. Afterquakes continue Pacific Plate North American Plate Eurasia Plate Philippine Plate 11/Mar Quake Afterquakes Previous quakes

4. 17/May/2011Pisa Seminar 2011 J-PARC Introduction What is J-PARC (Japan Proton Acceleration Research Complex)? –Joint project between JAEA and KEK –New and exciting accelerator research facility, using MW-class high power proton beams at both 3 GeV and 30 GeV. – Various secondary particle beams neutrons, muons, kaons, neutrinos, etc. produced in proton-nucleus reactions –Three major scientific goals using these secondary beams Particle and Nuclear physics Materials and life sciences R&D for nuclear transformation (in Phase 2) –The anticipated goal is 1 MW

5. 17/May/2011Pisa Seminar 2011 J-PARC Accelerator Muon Neutron Muon Neutron 3GeV proton Muon Kaon Muon Kaon < 30GeV proton

6. 17/May/2011Pisa Seminar 2011 Status of Accelerator From 2008 four secondary beams have been obtained exactly on schedule; –neutron beams (May, 2008) –muon beams (September, 2008) –kaon beams (February, 2009) –neutrino beams (April, 2009) Linac 181MeV –Upgrade to 400MeV in 2013 –nEDM measurement proposal RCS (booster) 3GeV –120-300 kW operation for Material Life Science Facility –Particle physics experiments using muon MR (Main Ring) 30 GeV –100-150 kW operation with fast extraction for T2K –10kW operation with slow extraction for 2ndary beam expts } } @ 3GeV RCS @ 30GeV MR

7. 17/May/2011Pisa Seminar 2011 An Expected Beam Power Curves defined before the earthquake BEAM POWER [MW] MR CYCLE [sec] 2008 2009 2010 2011 2012 2013 2014 2015 H20 H21 H22 H23 H24 H25 H26 H27 6sec (2.7%) 3.52sec (4.5%) 3.2sec (5.0%) 1.0sec (16%) 2.23sec (7.2%) P MR (8-bunch@30GeV) = 1.6 x P RCS / MR CYCLE RCS POWER FOR MR 2.47 (6.5%) MR POWER AT 30GeV (maximum cycle with existing power supply) ★ 0.72MW JFY ( ): Beam transfer ratio from RSC to MR now Linac energy upgrade

8. 8 17/May/2011Pisa Seminar 2011 J-PARC Damage by Earthquakes No damage by Tsunami All equipments are standing at where they should be but... –Need alignment again LINAC/T2K near detector floors were covered by underground water –quickly removed when the electricity was recovered Many cracks on the wall in tunnels Vacuum inspection is necessary Inspection and recovery are in progress Plan to provide beam for experiments at the end of this JFY Power Receiving Station Booster Tunnel

9. 17/May/2011Pisa Seminar 2011 introduction mu-e conversion physics

10. 17/May/2011Pisa Seminar 2011 Introduction Lepton Flavour Violation of Charged Leptons Neutrino Mixing (confirmed) Charged Lepton Mixing (not observed yet) Sensitive to new Physics beyond the Standard Model Very Small (10 -52 )  e       e ??  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

11. 17/May/2011Pisa Seminar 2011 What is μ-e Conversion ? 1s state in a muonic atom Neutrino-less muon nuclear capture (=μ-e conversion)  −  e −  nucleus  −  ( A, Z )     ( A, Z − 1) B(  − Ne − N)  Γ (  − N e − N) Γ (  − N  N ' )  −  ( A, Z ) e −  ( A, Z ) nuclear muon capture muon decay in orbit lepton flavors changes by one unit      −

12. 17/May/2011Pisa Seminar 2011 μ-e conversion Signal 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 Accidental Detector performance resolution, high rate  -e conversion BeamBeam background

13. 17/May/2011Pisa Seminar 2011 μ  eγ and μ-e conversion If   e  exits,  -e conv must be Even if   e  is not observed,  -e conv may be –Loop vs Tree –Searches at LHC Z’

14. 17/May/2011Pisa Seminar 2011 Comparison between   e  and  -e Conversion (Physics Sensitivity) Photonic and non-photonic (SUSY) diagrams photonicnon-photonic   e  yes (on-shell)no  -e conversion yes (off-shell)yes

15. 17/May/2011Pisa Seminar 2011 What can we learn from cLFV search? Mass matrix information of SUSY sleptons Off-diagonal components –How SUSY is breaking? –What kind of LFV interactions at GUT scale?

16. 17/May/2011Pisa Seminar 2011 SUSY-GUT and Seesaw LFV @ Planck mass scale SUSY-GUT Yukawa interaction SUSY Seesaw Model Neutrino Yukawa interaction CKM matrixNeutrino oscillation L.J.Hall,V.Kostelecky,S.Raby,1986;A.Masiero, F.Borzumati, 1986

17. 17/May/2011Pisa Seminar 2011 cLFV Search and LHC Masiero et al. JHEP03 (2004) 046

18. 17/May/2011Pisa Seminar 2011 cLFV Search and  oscillation, g-2 This Experiment Hep-ph/0607263v2 S.Antusch et al |δ 12 LL | = 10 −4 and |δ 23 LL | = 10 −2 300 GeV ≤ M~ ℓ ≤ 600 GeV 200 GeV ≤ M 2 ≤ 1000 GeV 500 GeV ≤ μ ≤ 1000 GeV 10 ≤ tan β ≤ 50 A U = −1 TeV M˜q = 1.5 TeV. and the GUT relations. B-physics constraints case shown in red hep-ph/0703035v2 G.Isidori et al This Experiment 0.002 Current Bound ~10

19. 17/May/2011Pisa Seminar 2011 0  and  -e conversion 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 Γ 0  RPV-SUSY LRSM

20. 17/May/2011Pisa Seminar 2011 MEG at PSI Status Physics data production started in 2008 Current published limit Br(   e  )<2.8x10 -11 (at 90% C.L.) (MEGA world record 1.2x10 -11 ) –Probability to obtain this limit given the average expected limit of 1.3x10 -11 is 5% Will reach the MEGA limit with 2009 data and go further in 2010-2011 Event Distribution in 90% Box

21. 17/May/2011Pisa Seminar 2011 Status of Muon cLFV MEGASINDRUM IIMEG Los Alamos μ→eγ PSI μ-e conversion PSI μ→eγ Pulsed μ beam (28MeV/c) 4 x 10 7 s -1 (Cont.)  beam ( 52MeV/c) ~10 7 s -1 Cont.  beam (28MeV/c) 3 x 10 7 s -1 DAQ completed in 1995 PRD 65, 112002 UL 1.2 ｘ 10 -11 DAQ completed EPJ C47 337-346 (2006) UL (Au) 7 x 10 -13 DAQ in progress NP B834 (2010) 1-12 UL 2.8 x 10 -11

22. 17/May/2011Pisa Seminar 2011 History of  -e conversion search 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

23. 17/May/2011Pisa Seminar 2011 The SINDRUM-II Experiment (at PSI) 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

24. 17/May/2011Pisa Seminar 2011 The MELC and MECO Proposals The MECO Experiment at BNL Cancelled in 2005  mu2e @ Fermilab MELC (Russia) and then MECO (the US) To eliminate beam related background, beam pulsing was adopted (with delayed measurement) To increase a number of muons available, pion capture with a high solenoidal field was adopted For momentum selection, curved solenoid was adopted

25. 17/May/2011Pisa Seminar 2011 Mu2E @ Fermilab Fermilab Accelerators The mu2e Experiment at Fermilab. –Proposal has been submitted. CD-1 approval –After the Tevatron shut-down uses the antiproton accumulator ring the debuncher ring to manipulate proton beam bunches

26. 17/May/2011Pisa Seminar 2011 C. Bhat and M. Syphers Mu2e Acc WG meeting Mar 9, 2010

27. 17/May/2011Pisa Seminar 2011 cLFV Search Experiment 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 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 if possible)! COMET (COherent Muon Electron Transition) –Submitted a proposal to J-PARC in 2008 and a CDR in 2009, –and obtained Stage-1 approval in July 2009 –TDR in preparation, will be published in 2011

28. 17/May/2011Pisa Seminar 2011 COMET An Experimental Search For Lepton Flavor Violating  - - e - Conversion at Sensitivity of 10 -16 http://comet.phys.sci.osaka-u.ac.jp

29. 17/May/2011Pisa Seminar 2011 Collaboration

30. 17/May/2011Pisa Seminar 2011 Overview of the COMET Experiment Proton BeamProton Beam –p–p–p–p –8GeV, ~7  A The Muon SourceThe Muon Source –Proton Target –Pion Capture –Muon Transport The DetectorThe Detector –Muon Stopping Target –Electron Transport –Electron Detection

31. 17/May/2011Pisa Seminar 2011 Proton BEAM

32. 17/May/2011Pisa Seminar 2011 Requirements for the Beam 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 −−−− 0.88  s  -e conv

33. 17/May/2011Pisa Seminar 2011 Requirements for the Proton Beam Proton beam structure for the mu-e conversion search –100nsec bunch width, 1.3 (or 1.7)  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 1.3 or 1.7  s 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 N bg = NP x R ext x Y  /P x A   x P  x A NP : total # of protons (~10 21 ) R ext : Extinction Ratio (10 -9 ) Y  /P :  yield per proton (0.015) A  :  acceptance (1.5 x 10 -6 ) P  : Probability of  from  (3.5x10 -5 ) A : detector acceptance (0.18) BR=10 -16, N bg ~ 0.1  Extinction < 10 -9 ExtractionAcceleration

34. 17/May/2011Pisa Seminar 2011 Proton Acceleration at J-PARC Proton acceleration in –LINAC –Booster (RCS) –Main Ring Nominal scheme –RCS: h=2 –MR:h=9 8 buckets filled 1 empty bucket, used for kicker excitation MR RF cavities are designed for this scheme –h=18 optional by removing capacitors on cavities –Need long shutdown to change the configuration 8 filled buckets out of 9 buckets 30

35. 17/May/2011Pisa Seminar 2011 J-PARC Proton Acceleration for COMET 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 1.7  s 3 batch injection

36. 17/May/2011Pisa Seminar 2011 RCS, MR Injection Acceleration and extraction in 20msec Bunch configurations –Micro bunch 324 MHz LINAC –Intermediate bunch ~1MHz Chopper –Macro bunch 25Hz RCS 池上雅紀 高エネルギーニュース vol.25 No.4 MLF RCS MR

37. 37 17/May/2011Pisa Seminar 2011 Double Kick Injection to MR Sweeping proton leakage in empty buckets caused by pulse formation inefficiency before LINAC acceleration Kick injected bunches again after a single turn with a delayed phase by a half cycle Sweep out the residual particles in the empty bucket After single turn

38. Double Kick Injection Performance Measurement using an abort-line monitor Installed inside the beam pipe of the MR abort line Diagnose the beam longitudinal (time) structure Wide dynamic range 4 PMTs viewing a single scintillator plate Different light attenuation using ND filters Improving factor < 10 -6 Normal InjectionDouble-kick Injection

39. 17/May/2011Pisa Seminar 2011 LINAC Chopper 池上雅紀 高エネルギーニュース vol.25 No.4 Two Cavities

40. 17/May/2011Pisa Seminar 2011 Muon/pion production

41. 17/May/2011Pisa Seminar 2011 Pion Production Target low-E pions – for low-E muons to stop – Backward extraction pion yield is proportional to T proton – pion yld is proportional to Beam Power Target material – High-Z Metal Rod like tungsten or gold Water cooling – Graphite Helium gas cooling Target radius optimization

42. 17/May/2011Pisa Seminar 2011 Pion Capture > 5 T at the target position – capture p t < 120 MeV/c Radiation Shield < 100 W on SC coil – 3-4 kW @ target – 35 kW @ W Shield – 2x10 -5 W/g @ coil Yields – 0.05(  +  )/8-GeV-proton  -yield vs. B max MARS simulation 0 2 4 6 8 10 12 14 16 18 20

43. 17/May/2011Pisa Seminar 2011  -Capture Solenoid Heat-load density : 2 x 10 -5 W/g behind W shield Utilize Al stabilized SC cable to reduce a heat load to the cold mass. – Cable dimension: 15mm x 4.7mm Al-SC: one of world leading expertise of KEK Length(mm)Thickness (mm)  Current (A/mm2) Coil 1120090 (6 layers)53.0 Coil 2140030 (2 layers)53.0 Coil 360030 (2 layers)53.0 Coil 430060 (4 layers)62.9

44. 17/May/2011Pisa Seminar 2011 Muon transport

45. 17/May/2011Pisa Seminar 2011 Muon Transport Guide  ’s until decay to  ’s Suppress high-p particles  ’s : p  < 75 MeV/c  ’s : p  < 75 MeV/c e’s : p e < 100 MeV/c e’s : p e < 100 MeV/c Beam collimator Beam Blocker

46. 17/May/2011Pisa Seminar 2011 A center of helical trajectory of charged particles in a curved solenoidal field is drifted by –This effect can be used for charge and momentum selection. This drift can be compensated by an auxiliary field parallel to the drift direction High-p Suppression See “Classical Electrodynamics”, J.D.Jackson Ch.12-Sec.4  p/  x = 1 MeV/c/cm

47. 17/May/2011Pisa Seminar 2011 Spectra at the End of the Muon Transport Preliminary beamline design –main magnetic field –compensation field –Inner radius of transport magnet cryostat (175 mm) Transport Efficiency Spectra at the end of the beamline ( top left) total momentum (top right)pt vs pL (bottom left) time of flight (bottom right) beam profile. # of  /proton 0.0071 # of stopped muons/proton 0.0035 # of muons with p>75MeV/c / proton 10 -5 Dispersion on the muon beam just before the collimator. 75 MeV/c

48. 17/May/2011Pisa Seminar 2011 The COMET Detector

49. 17/May/2011Pisa Seminar 2011 The COMET Detector to stop muons in the muon stopping target to eliminate low-energy beam particles and to transport only ~100 MeV electrons. to detect and identify 100 MeV electrons. under a solenoid magnetic field.

50. 17/May/2011Pisa Seminar 2011 Muon Stopping Target Light material for delayed measurement (1 st choice) – Aluminum :   - = 0.88  s Thin disks to minimize electron energy loss in the target – R = 100 mm, 200  m t, 17 disks, 50 mm spacing Graded B field for a good transmission in the downstream curved section. Good  -Stopping efficiency:  =0.66 – Muon rate 1.5x10 11 /sec – stopped-muon yields:~0.0023  ’s/proton

51. 17/May/2011Pisa Seminar 2011 Curved Solenoid Spectrometer Torus drift for rejecting low energy DIO electrons. – rejection ~10 -6 : < 10kHz Good acceptance for signal electrons (w/o including event selection and trigger acceptance) – 20% 60-MeV/c DIO electrons 105-MeV/c  -e electron

52. 17/May/2011Pisa Seminar 2011 Electron Detectors Rate < 800 kHz Straw-tube tracker to measure electron momentum –5 Planes with 48cm distance,  p = 230 keV/c One plane has 2 views (x and y) with 2 layers per view. A straw tube has 25mm thick, 5 mm diameter. –should work in vacuum and under a magnetic field. –<500  m position resolution. Crystal calorimeter for Trigger –GSO, PWO, LYSO, or new crystals …

53. 17/May/2011Pisa Seminar 2011 Tracking Detector Main detector to measure Ee –Thickness should be about 0.01 radiation-length to suppress % backgrounds. –Spatial resolution < 0.5 mm –Hit multiplicity ~ 1 per plane per event Straw tube tracker –5mm&, 208 tubes per sub-layer –four layers per station –anode readout (X, X’, Y, Y’) –five stations, 48 cm apart Amps and Digitizers (DRS ?) are in vacuum Optical-link to the outside of the vacuum vessel

54. 17/May/2011Pisa Seminar 2011 Trigger Calorimeter Trigger Source –Timing for Tracker Energy measurement –Better trigger condition –Redundancy to Ee measurement –E/p cut to cosmic muons Position measurement –Improve track recognition. –f = 92 kHz per crystal –Crystal R&D is in progress at JINR Possible Photon Detectors (operational in vacuum and magnet) –APD –MPPC

55. 17/May/2011Pisa Seminar 2011 Cosmic Ray Shields Both passive and active shields are used Passive shields –2 meter of concrete and 0.5 m thick of steel against skyshine neutron –Need additional passive study to protect CR veto counter from muon capture neutrons. Under investigation. Active shields –layers of scintillator veto counters (~1% inefficiency)

56. 17/May/2011Pisa Seminar 2011 Experimental Space A possible layout Discussion in the task force –Target and beam dump outside the hall –Share the upstream proton transport line with the high p beam line –External extinction device in the switch yard

57. 17/May/2011Pisa Seminar 2011 Signal Sensitivity 2x10 7 sec running 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

58. 17/May/2011Pisa Seminar 2011 Potential Background Events 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)

59. 17/May/2011Pisa Seminar 2011 Intrinsic Background (from muons) 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.

60. 17/May/2011Pisa Seminar 2011 DIO Background a number of events for 1.1 x10 18 stopped muons. <0.05 events

61. 17/May/2011Pisa Seminar 2011 Beam Related Background Rejection 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)

62. 17/May/2011Pisa Seminar 2011 Beam Related Backgrounds (and CR) 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

63. 17/May/2011Pisa Seminar 2011 Background Estimation Summary 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

64. 17/May/2011Pisa Seminar 2011 R&D Status

65. 17/May/2011Pisa Seminar 2011 R&D Status Straw-tube tracker –Done by Osaka group for MECO Crystal calorimeter Transport Solenoid Extinction Measurement –Device R&D Gas Cherenkov + Gated PMT –Extinction measurement at J- PARC MR

66. 17/May/2011Pisa Seminar 2011 Straw-tube Tracker R&D Seamless type tube (I.S.T.) –Thickness : 25  m –Diameter : 5mm –Material : polyimide+carbon –Resistance : 6M /sq ASIC design for readout electronics is going with KEK electronics group Prototype Straw-tube chamber Beam test using 2.0GeV/c pion beam in 2002

67. 17/May/2011Pisa Seminar 2011 Calorimeter R&D GSO crystal for PET use –Stack in 3D –Light loss across the connection Agreement btw data & MC Need further study –Stacking method –Readout –Radiation hardness? 30mm x 32mm x 120mm Stack of 5 x 8 x 4 crystals

68. 68 17/May/2011Pisa Seminar 2011 R&D on Electron Calorimeter Fast crystal for electron energy measurement –GSO(Ce), LYSO, or LaBr3 MPPC or APD readout Crystal R&D in JINR / Performance test in Japan

69. 17/May/2011Pisa Seminar 2011 Transport Solenoid Design

70. 17/May/2011Pisa Seminar 2011 R&D on the Transport Solenoid Transport Solenoid would be easier than the capture solenoid: – field magnitude ~ 2 T –smaller radiation load NbTi copper stabilized conductor, which is widely used in MRI magnets and commercially available, will be used. The solenoid will be constructed by arranging coil “pancakes” electrically and thermally connected in series along the curve. We are studying basic parameters by a prototype comprising of 3 pancakes. –cooling performance –electromagnetic forces between pancakes –quench back system A new high-Tc superconductor, MgB2, will be used for one of the coils for the first time. –MgB2 will be used for the electron-spectrometer and detector solenoids

71. 71 17/May/2011Pisa Seminar 2011 Engineering Design of the Magnet System Technical design studies are going on with Toshiba Co. –optimized magnetic field distribution based on coil designs –cryostat structure and support system – integration scheme

72. 17/May/2011Pisa Seminar 2011 Extinction Measuring Device Monitor extinction level online by using a Gas Cherenkov detector with gating PMTs –Blind to proton beam core, active only in between proton pulses (nsec) Aiming at Repetition ~1MHz On/off ratio <10 -6 Long-term operation 280V, 10kHz, fall t ~100nsec

73. 17/May/2011Pisa Seminar 2011 Extinction Measurement using Secondary Beam Measure secondary particle time structure relative to a reference signal from the MR – MR RF signal in the experimental area – Beam line hodoscope counters at the K1.8BR line Support by E15/E17 group – MR operation with empty buckets – Bunched slow extraction – Count the number of secondary particles as a function of time Particle identification – TOF Integration for ~10 3 seconds supposing 1MHz counting rate Delayed reference signalsCounter signal proton 

74. 17/May/2011Pisa Seminar 2011 Extinction Measurement Utilize beam monitor in the abort line Single bunch operation of the MR – Look at the empty bucket before the filled one – Detector that can count the number of protons Two layers of 2mmt scintillator hodoscopes – Support by thin carbon fiber plates – Read by Multi-anode PMT through optical fibers – Operated in the beam line vacuum

75. 17/May/2011Pisa Seminar 2011 First Shot ! RCS single bunch operation Fast extraction to the abort line, First the empty bucket and then filled bucket Abort line monitor HV 300V Outside counter normal gain Kicker excitation signal Beam intensity monitor

76. 17/May/2011Pisa Seminar 2011 Chopper Phase Optimization Factor of 2.5 improvement  Extinction < 2 x 10 -5 –Estimated only from pulse height –Perhaps better than this because of scintillator saturation The chopper (two cavities) is currently driven by a single power supply. Operation with two independent power supply is planned. This is expected to improve.

77. 77 17/May/2011Pisa Seminar 2011 Slow Extraction R&D Measure the time structure of the primary proton beam –Secondary beam at K1.1BR –800MeV/c, pion dominant, 200k/spill –Primary Beam Condition h=9, 3 filled and 6 empty 30GeV Bunched Slow Extraction –Bunch ID using MR Flat Top and RF signals –Read out Measure secondary beam (~100k sample/spill) for tens of minutes and get 10 8 samples K1.1BR Layout K1.1BR Target Proton Beam 3 K1K2 K3 K4

78. 78 17/May/2011Pisa Seminar 2011 Extinction Measurement Result Normal beam injection to MR Integration over 20 minutes Extinction level at (5.4±0.6)×10 -7

79. 17/May/2011Pisa Seminar 2011 Schedule and Construction Cost Funding starting 1st year design & order of SC wires 2nd year 3rd year 4th year 5th yearengineering run 6th yearphysics run construction 1 Oku JPY ~ 1.15 M Euro

80. 80 17/May/2011Pisa Seminar 2011 Yet Another Mu-e conversion Search at J-PARC DeeMe

81. 81 17/May/2011Pisa Seminar 2011 μ-e electrons may directly coming from a production target An electron analogue of the surface muon. Experiment could be very simple, quick and low-cost. Masa → DeeMe

82. 82 17/May/2011Pisa Seminar 2011 DeeMe Overview Proton beam from RCS Pion production target as a muon stopping target –Replace the current graphite target with a SiC target –Si has larger muonic-nuclear capture rate Beam line as an electron spectrometer –Secondary beam-line kicker to remove prompt BG –Only delayed electrons enter the spectrometer S.E.S. 1.5×10 -14 for 2×10 7 sec DAQ 3GeV Proton

83. 17/May/2011Pisa Seminar 2011 Summary New experiment (COMET) to search for mu-e conversion at J- PARC COMET aims at achieving a sensitivity of 10 -16 –High-intensity, high-purity pulsed proton beam at J-PARC –Curved solenoid muon transport/spectrometer to suppress backgrounds efficiently R&D work in progress –Detector –Magnet –Proton beam Beam structure Extinction

84. 17/May/2011Pisa Seminar 2011 Backup

85. 85 17/May/2011Pisa Seminar 2011 Target Material fc:Fraction of the atomic capture of muon to the atom of interest – single ‐ element material: fc = 1 –composite material:proportional to Z (Fermi-Teller Z law) Silica ‐ carbide Si:C=7:3 f MC :muonic nuclear ‐ capture rate –(1-f MC )=f free ‐ decay ‐‐‐ useless muons: large f MC is better On the other hand, τ μ ‐ >300 nsec (light Z) to avoid the prompt background Engineering point of view: –good thermal shock resistance –high melting point –good radiation resistance

86. 17/May/2011Pisa Seminar 2011 High-frequency Chopper

87. 17/May/2011Pisa Seminar 2011 Additional Extinction Means Bunch Cleaner Bunch Cleaner in MR in MR tested at AGS for MECO tested at AGS for MECO AC-dipole AC-dipole @ primary beamline @ primary beamline f extinction ~ 1/100 f extinction ~ 1/100 collaboration with mu2e collaboration with mu2e

88. 17/May/2011Pisa Seminar 2011 Background Event signature –P e = 105 MeV/c –T e > ~μsec Any particle production 1  sec later than the prompt proton timing? –Only decay product of  Michel electron P e <55MeV/c If any off-timing proton exists, that can be BG –Extinction < 10 -14 mu-e conversion DeeMe