1. 2 pages of DeeMe

2. Forbidden in the Standard Model Discovery will be a significant result: Evidence of the new physics beyond the SM Answer to the light neutrino mass Complementary to the LHC Current Upper Limits (SINDRUM-II@PSI) BR[μ- Ti→ e- Ti] < 4.3 × 10 -12, BR[μ- Au→ e- Au] < 7 × 10 -13 Branching ratios could be different between light/heavy nucleus. Theory Predictions: BR = 10 -12 ~10 -17 photonic: ~ BR(μ→eγ) ×O(α) ~ 10 -14 non-photonic: cannot study with μ→eγ MEG(PSI): BR[μ→eγ] < 2.4 × 10 -12 –on going COMET/Mu2E: BR[μ-e conv.] < 10 -16 – planned(2019~) DeeMe(J-PARC MLF): BR[μ-e conv.] ~ 5×10 -15 Aiming to start from 2015. photonic non-photonic μ - + N → e - + N DeeMe ゴール DeeMe B(μ→e conv) > 10 -14 Little Higgs Extra Dim. SUSY MEG Goal DeeMe Final (5x10 -15 ) DeeMe 1st (2x10 -14 )

3. 3 DeeMe Search for μ-e conversion electron directly emerging out of the primary target. N μ- stopped @ the primary target (graphite@2009): ~10 10 /sec/MW Plan of the experiment Replace the existing Graphite target with SiC. Extract delayed electrons with 105 MeV/c of the beam momentum by H line Precisely measure the electron momentum with a spectrometer. Sensitivity ： S.E.S. = 5 × 10 -15 (8×10 7 sec) 、 MLF runs 2×10 7 sec per year. Can run completely independent of T2K, hadron-hall experiments, neutron experiments, muon experiments with D-, U-, S-lines. H-line with large acceptance: H-line can be used for g-2/EDM experiments. Good for the effective use of J-PARC facility: maximize the outputs from J-PARC. DeeMe g-2/EDM surface-μ H-line @MLF Spectrometer Hodoscope Tracker Focus Solenoid Prompt Kicker Bend Mag. Focus Solenoid Capture Solenoid Pulsed Proton Beam SiC Rotation Target

4. 4 Cost and Schedule ItemCost (kJPY)sub totalNote Detector103,000(73,000) Spectrometer Magnet30,000 Hodoscope10,000gating-grid type WC R&D3,000 WC Construction50,000 Readout Electronics10,000 Target30,000 SiC Target30,000 H-Line ConstructionFacility Prompt Kicker220,000 Magnet60,000 Power Supply160,000 PostDoc (3)15,000/y75,000 Total428,000 Multi-purpose beamline: Can be used for other experiments 20112012201320142015 Design Grant-in-Aid submit H-Line const. Upstream Downstream Kicker Detector Run Analysis

5. Many pages of DeeMe

6. Experimental Search for μ-e Conversion in Nuclear Field at Sensitivity of 10 -14 with Pulsed Proton Beam from RCS --- DeeMe --- M. Aoki, Osaka University on behalf of DeeMe Collaboration MuSAC 2012/2/18

7. 7 DeeMe Collaboration M. Aoki (1), Y. Miyake (2), K. Shimomura (2), N. Kawamura (2), P. Strasser (2), S. Makimura (2), M. Kinsho (3), K. Yamamoto (3), P.K. Saha (3), H. Kobayashi (3), H. Matsumoto (3), C. Ohomori (3), M. Ikegami (3), M. Yoshii (3), S. Mihara (4), H. Nishiguchi (4), K. Yoshimura (4), N. Saito (4), T. Mibe (4), D. Bryman (5), T. Numao (6) (1) Osaka University (2) KEK MUSE (3) KEK Accelerator (4) KEK IPNS (5) UBC (6) TRIUMF

8. 8 Muon in the Standard Model of Particle Physics There are three generations (flavors) of Quarks and Leptons. Muon was found at 1936. – I.I. Rabi said “ Who ordered that? ” Is the muon excited state of electron? – The world-first search for muon rare process:  - > e  @1947 – Null Result → a hint of generation BR theory (  ->e  )~10 -4 @ 1958 – But exp. already gave BR exp. < 2 x 10 -5 – → Two neutrinos model  e ≠   @1962 BNL – Toward the establishment of the concept of “ generation/flavor ”. (g-2) μ @BNL hints physics beyond the Standard Model Muon played very important role in the development of particle physics.

9. 9 flavor of elementally particles Quark Mixing – Cabbibo-Kobayashi-Maskawa (CKM) Matrix – Established --- Novel Prize@2008 Neutrino Mixing – Pontecorvo-Maki-Nakagawa-Sakata (PMNS) Matrix – Homestake, Kamiokande, SNO etc. – Observed and Established. Charged Lepton Flavor Violation (CLFV) – No observation yet at all. – Implemented to the Standard Model of Particle Physics as “ forbidden ”. sbd uct  e ee    ?? Quarks Leptons

10. 10 Charged Lepton Flavor Violation (CLFV) Forbidden in the Standard Model of particle physics. μ - +A→e - +A, μ→eγ, μ→eee, τ→e(μ)γ, τ→e(μ)h... νSM: Neutron Oscillation may induce the effective CLFV, but it is very small due to the combination of GIM-like mechanism and smallness of the neutrino masses. CLFV → Clear evidence of the physics beyond the Standard Model with neutrino-oscillation extension. Charge Lepton Flavor Violation A. de Gouvea

11. 11  Muonic Atom (1S state) – MC:MDO = 1:1000(H), 2:1(Si), 13:1(Cu) – τ(free μ-) = 2.2 μs – τ(μ - ;Si) = 0.76 μs charged Lepton Flavor Violation (CLFV) nuclei −− Muon Decay in Orbit (MDO) μ-e Conversion in Nuclear Field Muon Capture(MC) Clear evidence of the new physics

12. Physics of μ-e Conversion SUSY-GUT, SUSY-seesaw (Gauge Mediated process) BR = 10 -15 = BR(μ→eγ) × O(α) τ→lγ SUSY-seesaw (Higgs Mediated process) BR = 10 -12 ~10 -15 τ→lη Doubly Charged Higgs Boson (LRS etc.) Logarithmic enhancement in a loop diagram for μ - N → e - N, not for μ→e γ M. Raidal and A. Santamaria, PLB 421 (1998) 250 Little Higgs Models Randall-Sundrum Models SUSY with R-parity Violation Leptquarks Heavy Z’ Multi-Higgs Models N N

13. Relations with other observables G. Ishidori et al., PRD 75 (2007) 115019 Recent Upper Limits SINDRUM-II: BR[μ - + Au → e - + Au] < 7 × 10 -13 SINDRUM-II: BR[μ - + Ti → e - + Ti] < 4.3 × 10 -12 TRIUMF: BR[μ - + Ti → e - + Ti] < 4.6 × 10 -12

14. Physics of slepton mass matrix CLFV μ g-2 μ EDM RealImaginary  -LFV slepton mass matrix

15. Physics of slepton mass matrix CLFV μ g-2 μ EDM RealImaginary  -LFV slepton mass matrix

16. 16 DeeMe DeeMe A transparency of J. Hisano at IFMF WS 2010 (DeeMe lines added by M. Aoki)

17. Little Higgs Model Randall & Sundrum DeeMe

18. (Hisano IFMFS2010)

19. μ→eγ vs. μ-e conversion photonic-likenonphotonic-like B(μ→e conv) > 10 -14 Little Higgs Extra Dim. SUSY MEG Goal DeeMe Final (5x10 -15 ) DeeMe 1st (2x10 -14 )

20. 20 Principle of Measurement Signal : μ - +(A,Z) → e - +(A,Z) – A single mono-energetic electron 105 MeV Delayed ： ~1μS No accidental backgrounds Physics backgrounds – Muon Decay in Orbit (MDO) E e > 102.5 MeV (BR:10 -14 ) E e > 103.5 MeV (BR:10 -16 ) – Beam Pion Capture π - +(A,Z) → (A,Z-1)* → γ+(A,Z-1) γ → e + e - Prompt timing SINDRUM II SINDRUM II Results BR[μ - + Au → e - + Au] < 7 × 10 -13 BR[μ - + Ti → e - + Ti] < 4.3 × 10 -12

21. General Idea of μ-e conv. exp. Sensitivity – High  - yield – High Power Proton Background – Pulsed Proton 1 MW pulsed proton from RCS

22. 22 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.

23. 23 DeeMe Process : μ - +(A,Z) → e - +(A,Z) – A single mono-energetic electron 105 MeV Delayed ： ~1μS No accidental backgrounds Physics backgrounds – Muon Decay in Orbit (DIO) E e > 102.5 MeV (BR:10 -14 ) E e > 103.5 MeV (BR:10 -16 ) – Beam Pion Capture π - +(A,Z) → (A,Z-1)* → γ+(A,Z-1) γ → e + e - Prompt timing Low Energy main part: suppressed by the beamline. High Energy tail: Magnet Spectrometer (Δp < 0.3%) Main pulse: Kicker to reduce the detector rate. after-protons: Suppressed owing to the extremely small after-protons from RCS -- R AP <10 -17.

24. mu-e conversion After-Proton (beam related) BG

25. J-PARC MLF Muon Facility 3-GeV Proton Proton Target Proton Beam 1 MW : 3 GeV, 333 μA High statistics Pulse Beam: 25 Hz 50 pulses Low backgrounds H-line

26. 26 Beamline: H-line the 1st concept by Jaap Doornbos (TRIUMF) – multi purpose beamline DeeMe + g-2 + muonium-HFS – large acceptance > 110 msr – straight section for kickers and a separator. – moderate Δp so that the BG ’ s can be monitored simultaneously. DIO backgrounds (p < 102.5 MeV/c) Prompt backgrounds (p > 105.0 MeV/c) Detailed design is ongoing by MUSE/IMSS/J-PARC. Not fully optimized yet DIO BG Signal Prompt BG

27. 27 Target Material f MC : muonic nuclear-capture rate – (1-f MC )=f free-decay --- useless muons: large f MC is better: larger Z. On the other hand, τ μ- > 300 nsec (light Z) to avoid the prompt background f C : Fraction of the atomic capture of muon to the atom of interest – single-element material: f c = 1 – composite material: proportional to Z (Fermi- Teller Z law) Silicon-Carbide --- Si:C = 7:3 Silicon-Carbide: – good thermal shock resistance: ΔT=450°C – high melting point: >1450°C – good radiation resistance 10 dpa @ 1000°C or more target materialf C × f MC Graphite0.08 Silica-carbide (SiC)0.46 SiC Muon Target: 6 times higher physics sensitivity!!! Silicon Carbide CERASIC

28. 28 Sensitivity and Backgrounds Signal Sensitivity – S.E.S.: 2×10 -14 (for 2×10 7 sec of run) Backgrounds – Assuming R AP =10 -19 (based on the recent R&D) – Detector live-time Duty = 1/20000 If we could extend the running-time up to 8×10 7 sec – Standard Cut: S.E.S.= 0.5 × 10 -14 (N BG =0.48) – Tighter Cut: S.E.S.= 0.6 × 10 -14 (N BG <0.02) DIO BG μ-e signal Beam BG or much less Signal Region: 102.0 -- 105.6 MeV/c

29. 29 DIO BG Signal Prompt BG In-situ Monitoring of Backgrounds Moderate Δp of H-line makes it possible to monitor backgrounds in situ. – DIO backgrounds (p < 102.0 MeV/c) – Prompt backgrounds (p > 105.6 MeV/c) Signal Sensitivity Calibration – Calibrated by using number of DIO electrons. – N DIO =300 (2e7 sec) Background Monitoring – DIO electrons shape yield – Prompt Backgrounds p>105.0 MeV/c (direct upper limit) Beam-loss counters in RCS – Cosmic-induced Backgrounds Beam-on: 50μsec/sec Beam-off: >500msec/sec Cosmic BG Signal (Prompt BG)

30. 30 R & D Items H-line – Large Acceptance (> 110 msr) Kicker – Large Aperture (320-mm × 320-mm) – High Field > 385 G – Fast fall < 300 nsec After-protons from RCS SiC Target – Impact on the downstream of the primary. Detector – Drift Wire Chamber: that can be operated after 33k of the prompt burst.

31. 31 Secondary-Beamline Kicker prompt burst: coincide with the primary proton pulse from RCS. – ~100M particles/pulse (test measurement at 2009 && Geant4 MC) detector (counter and wire chamber) will be blind for while. Reduce the prompt burst by kicker <1/20000 ~ 1/150000 – detector rate will be ~20k particles/extraction, and it is acceptable. Mag. Field> 385 Gauss Gap320 mm Width320 mm Length400 mm No.4 Fall Time< 300 nsec Rep. Rate25Hz Electric NoiseMinimum note: amount of the delayed particles in this figure is enlarged for the illustration.

32. Magnet Impedance matching elements Internal inductance INTERNAL INDUCTANCE FALL TIME @ 500 A 100 nH307 nsec 300 nH361 nsec 500 nH430 nsec 500 A 10 kA FALL TIME MAGNET COIL CURRENT [A] 1) MAGNET INDUCTANCE: 600 nH 2) IMOEDABCE MATICHING ELEMENT: 8000 pH, 100 Ohm 3) MAGNET COIL CURRENT: 10 kA 4) PFL IMPEDANCE: 5 Ohm MAY. 06, 2011 hiroshi.matsumoto@kek.jp

33. 33 研究計画概要 ビームライン – 実験感度向上のために大立体角ビームラインが必要である。そのために、 H ラインを新設する。 – H ラインは、ミュオン g-2 やミュオン HFS などの実験にも利用できる multi purpose beamline → 高い費用対効果費 ターゲット改造 – 回転ターゲットのサイズと素材を改造して、ミュオニック原子の収量を 上げる。 – 外径を 20 mm 大きくし、素材をシリコンカーバイドとする。 物理感度 – 2×10 7 秒の物理ランで 2×10 -14 の単一イベント感度に到達する。 – 更に物理ラン時間を延長することによって、 5×10 -15 の感度を目指すこと も可能。 スケジュールとコスト – 2015 年までに最初の物理結果を発表したい。 – 検出器 1.1 億円、 SiC 標的 0.3 億円、キッカー電磁石 2.2 億円 ＋ H ライン

34. 34 実験感度 Single Event Sensitivity: S R μ-stop : ミュオニック原子収量 -- ターゲット形状とサイズ f C : 目的の原子に捕獲される割合 -- ターゲット材料 f MC : muonic nuclear-capture rate -- ターゲット材料 A μ-e : ミュオン電子転換 - 電子に対するアクセプタンス -- ビームライン T: 測定時間 – 2 × 10 7 sec ( およそ 8 ヶ月 ) の物理データ収集期間とする。

35. 35 R μ-stop : ミュオニック原子収量 – プロダクションターゲットの形状できまる。 – Monte Carlo 計算の不定性は ~30% 以下 2009 のテスト実験で実証済 ターゲット形状 回転ターゲット外径 Rμ-stop 固定標的 5 × 10 9 /sec/MW 標準外径 10 × 10 9 /sec/MW 拡大外径 15 × 10 9 /sec/MW 遅延粒子タイミング

36. 36 Detector prompt burst = 33k per pulse even after suppressed by the kicker. BH1,2: hodoscope – gating PMT – Designed by T. Taniguchi, but he passed away. – Development is suspended. WC1-4: wire chamber – micro-cell or asymmetric-cell – Doable, but may need further R&D Amp. and readout FADC system. σ < 0.3 MeV/c gating PMT

37. 37 Detector Calibration Momentum Scale and Resolution – place a calibration target in HB2 – prompt positron burst --> g-2 branch – beam π+, μ+ stop in the target --> π e2, Michel positrons Acceptance Curve of H-line – exactly the same H-line settings: momentum@105 MeV/c, slits – reduce the primary proton by 10 -8 LINAC chopper: 10 -7 Length of macro-pulse: <10 -1 calibration target to g-2 branch DeeMe Spectrometer

38. 38 After-Protons from RCS Excellent design of RCS transverse acceptance – RCS ring aperture = 486π mm.mrad ring collimator aperture = 350π mm.mrad – Extraction Beamline aperture = 324π mm.mrad – Total kick angle = 17 mrad --- > 2000π mm.mrad Fast Extraction Scheme (not a slow extraction) Preliminary measurement of a beam-loss monitor showed promising result: R AP could be < 10 -19. Improved measurement will be performed in next February, 2012. RCS STR+BPM To MLF/MR STR+BPM QFLQDL Pulse KM 1~3 Pulse KM 4~8

39. 39 Preliminary Measurement after-protons are scattered protons. beam-loss counters can observe it. 258 hours of measurement. by Kazami Yamamoto No evidence of the after-protons so far. Measurement is limited by the electrical noise from the RCS kickers. The above snapshot gives R AP could be ~ 10 -19 It is required to be < 10 -17 The detectors will be improved for much better measurement in future.

40. MR MLF J-PARC Complex RCS の 2 RF バケツに LINAC から入 射 RCS 加速 20 msec RCS から早い取りだしで MLF へ 70 パルス /MR-cycle MR へ 4 パルス /MR-cycle ブランク 2 パルス /MR-cycle RCS ランプダウン 20 msec

42. 42 RCS から 3NBT への取出し 余裕のある RCS デザイン RCS リングアパーチャ = 486π mm.mrad コリメータアパーチャ = 350π mm.mrad 3NBT アパーチャ = 324π mm.mrad キック角 = 17 mrad --- > 2000π mm.mrad – キッカー off で 3NBT に取出されてしまう様なエミッタン スのビームは RCS リングを周回しない。 早い取りだし：取出し後にリング中にビームは存在しない。 – 理論値 : 0 – ビームカレントモニター実測値 : <1/500 RCS STR+BPM To MLF/MR STR+BPM QFLQDL Pulse KM 1~3 Pulse KM 4~8

43. 43 AP の発生メカニズムとモニター方法 リング中を周回している陽子はそのま までは AP とはならない。 取出し部の近傍で大エミッタンスに散 乱された粒子は AP となりうる。 – 残留ガスでの散乱 – ビームダクト内壁での散乱 そのような散乱粒子はむしろ取出しセ プタム電磁石の分岐部分にヒットしや すい。 取出し部分でのビームロスモニターで 観測できるはずである。

44. 44 G4Beamline による散乱陽子 MC 真空ダクト、セプタム 1,2,3 磁極、 コイル、リング Q 磁石 セプタム 3 出口下流、ビームダク ト左外側にカウンターを置いた場 合 : – N[ カウンターヒット ]/N[3NBT 通り抜け ] = ε=0.03 – 既存のロスカウンターでは、 ε=0.008

45. 45 ビームロスモニターによる測定 BLM: プラスチックシ ンチ + PMT 読み出し shingle hit sensitive 258 時間積算 by 山本風海 @ JAEA 総陽子数 4×10 20 Trigger efficiency = 100% BLM に見える大きな ノイズはキッカーか らの電磁ノイズ 取出し前：各バケツに高々 1 ヒット、 R AP < 10 -21 取出し後：キッカー電磁ノイズで見にくいがあっても僅か、 R AP <10 -18 DeeMe 要求レベル： R AP < 10 -17 BPM カレントモニター BLM 1 BLM 2

46. 46 Cost and Schedule ItemCost (kJPY)sub totalNote Detector103,000(73,000) Spectrometer Magnet30,000 Hodoscope10,000gating-grid type WC R&D3,000 WC Construction50,000 Readout Electronics10,000 Target30,000 SiC Target30,000 H-Line ConstructionFacility Prompt Kicker220,000 Magnet60,000 Power Supply160,000 PostDoc (3)15,000/y75,000 Total428,000 Multi-purpose beamline: Can be used for other experiments 20112012201320142015 Design Grant-in-Aid submit H-Line const. Upstream Downstream Kicker Detector Run Analysis

47. 47 Cost ItemCost (kJPY)sub totalnote detector73,000(103,000) Magnet(30,000) Hodoscope10,000gating-grid type WC development3,000 WC construction50,000 Readout10,000 Target30,000 SiC Target30,000 H-line1,480,000 HS1400,000 HS2-5300,000 HB150,000 HB2-490,000 Quads50,000 Kicker Mag.60,000 Kicker PS160,000 Vacuum30,000 Mag. PS300,000 Installation40,000 D-line Mod.70,000 Kicker PS PFN Mod.50,000 DSEPTUM Mod.20,000 Multi-purpose beamline: can be used for many other experiments. within: Grant-in-Aid for Scientific Research in Japan

48. 48 研究体制 extinction 測定器開発 extinction 測定 extinction 悪化メカニズムの解析 全体設計 トラッキングチェンバー開発 カウンター開発 物理解析 H ライン設計 建設 中古電磁石調達 バックアップ D ライン案検討 H ラインキッカー開発 バックアップ D ラインキッカー改造 国内外の大学にも参加を呼びかけてゆく 博士課程のテーマとしても最適

49. 49 研究体制 Osaka U. M. Aoki KEK MUSE: Y. Miyake, K. Shimomura, N. Kawamura, P. Strasser Accelerator: M. Kinsho, K. Yamamoto, P.K. Saha, H. Kobayashi, H. Matsumoto, C. Ohomori, M. Ikegami, M. Yoshii IPNS: S. Mihara, H. Nishiguchi, K. Yoshimura, N. Saito, T. Mibe UBC D. Bryman TRIUMF T. Numao 若手研究者の育成 科研費雇用研究員 大学院生

50. 50 Status KEK/IMSS Muon PAC: Stage-1 approved. J-PARC PAC: pre Stage-1, aiming to get Stage-1. The lab already started the procurement of magnets in the tunnel of H-Line. Kicker design: talking with Nippon-Koshuha for the detailed cost estimate. We also are communicating with BNL C-AD department. Gas wire chamber development is on-going. The 2nd stage of the after-proton measurement is ongoing. KAKENHI (Kiban S) application was submitted.

51. 51 Summary There is a competitive merit of physics in searching for μ-e conversion at sensitivity of 10 -14 in timely manner. Needless to say that the result should be obtained before the result from COMET and/or Mu2e. It will maximize the potential of major discovery at J-PARC. The experimental idea with which the physics result can be obtained within 5 years was proposed. It fits the research period of Grant-in-Aid for Scientific Research of Japan. It is necessary to build a large-acceptance beamline (H-line) for the best result. The H-line can be time-shared with other experiments, such as g-2. After protons are much smaller than that required from the experiment. The size of cost (except for the multi-purpose H-line) is within the range of the Grant-in-Aid for Scientific Research of Japan. R&D activities are on-going.

52. End of Slides

53. Ring aperture ( w/ magnets only) Begin Ext. Ins 1 st Foil Secondary Collimators Varying x or x’ at the starting x: ±32mm (~315  ) ~ ±92mm(~2600  ) x’:±6.5mrad (~320  ) ~ ±16mrad(~2000  ) 315  320  (~350 

54. 54 キッカーの役割 RCS からの陽子パルスに同期した prompt burst – 50M particles/pulse (2009 年テスト実験実測 ) 検出器が飽和してしまう。 – キッカーで prompt タイミングのみ <1/1000 に減らす。 検出器レート 33k particles/pulse 磁場 > 385 Gauss Gap320 mm Width320 mm Length400 mm 台数 4台4台 Fall Time< 300 nsec 繰り返し 25Hz 注 : 遅延粒子の量は大げさに図示してある。

55. 55 キッカーデザイン案 磁場 > 385 Gauss Gap320 mm Width320 mm Length400 mm 台数 4台4台 Fall Time< 300 nsec 繰り返し 25Hz KEK 加速器グループ 小林仁、松本浩

56. 56 Transmission Efficiency Internal Inductance = 100 nH Magenta: kicker current Green: mu-e signal strength @ birth Blue: mu-e signal @ detector Internal Inductance = 500 nH -10% --- acceptable

57. Magnet Impedance matching elements Internal inductance INTERNAL INDUCTANCE FALL TIME @ 500 A 100 nH307 nsec 300 nH361 nsec 500 nH430 nsec 500 A 10 kA FALL TIME MAGNET COIL CURRENT [A] 1) MAGNET INDUCTANCE: 600 nH 2) IMOEDABCE MATICHING ELEMENT: 8000 pH, 100 Ohm 3) MAGNET COIL CURRENT: 10 kA 4) PFL IMPEDANCE: 5 Ohm MAY. 06, 2011 hiroshi.matsumoto@kek.jp キッカーコンセプト Update By H. Matsumoto (KEK) 日本高周波とコンタクト

58. Test Measurement How many μ - are actually stopping in the production target?

59. J-PARC MLF Muon Facility 3-GeV Proton

60. Counters at the exit of D-Line D2 Exit Pb (4mm t ) Plastic Scintillator μ-μ- e-e- B1B2B3 B1: gating-PMT readout B2: gating-PMT readout B3: ND filter (1/1000), normal PMT readout Count only after the prompt beam-burst (>10 4 /pulse). Can’t close a beam slit to reduce the beam rate. Otherwise, it takes forever to accumulate the enough number of events. ➡ use gating-PMTs that can be turned-off during the prompt beam-burst. Beam μ - will produce delayed hits if they stop in the plastic scintillator. ➡ Pb plate to absorb μ - ➡ Electron detection efficiency ~ 50% @ 40 MeV/c

61. Signals taken by gating-PMT B1 Plas. Scinti. gating B2 Plas. Scinti. gating B3 Plas. Scinti. normal PMT ND filtered The baseline of the signal is not flat owing to the delayed fluorescence background, but individual hits are clearly observed as spikes on the baseline.

62. Analysis Record PMT signals by using500MHz FADC like E787/949. Subtract a baseline template from the recorded waveform. Maximum hight of the pulse tagged by the other counter shows clear valley between pedestal and signal. – The detection efficiency is sufficient. Real hits by the beam particles = B1*B2 – τ = 2.10±0.02 μs – Combination of τ μ +(2.2μs) and τ μ - -C (2.0μs). There is a contamination coming from e - produced by e + scattering where the e + is from Michel decay of μ + in the target. The number of stopped μ + is 450 times more than that of μ -. e - ~ e + /450 e - from e + scattering B1 pulse height (B2 tagged) B2 pulse height (B1 tagged)

63. P Spectrum 検出器の detection efficiency は鉛板の影響により、低エネルギ ーで落ち込むはず。 p e > 40 MeV/c では μ - 崩壊からの e - が支配的 p e ~ 50 MeV/c の Michel Edge は確かに Michel Edge p e < 30 MeV/c では μ + 崩壊からの e + の散乱 e - が支配的 この効果を補正すると → μ - stopping rate = 5 × 10 9 /sec/MW in the current Target. G4 では 7 × 10 9 /sec/MW e-e- e - from e + 散乱

64. gating PMT No. of particles in a prompt pulse ~1e4 Standard PMT is saturated. Used a gating PMT system – off/on gain ratio = 1e6 Designed by Taniguchi

65. Snapshot of PMT signal B1 Plas. Scinti. gating B2 Plas. Scinti. gating B3 Plas. Scinti. normal PMT ND filtered Baseline distortion due to delayed fluorescence from plastic scintillator. Individual hits by real particles can be seen on the baseline.

66. 66 G4Beamline Estimation 28 MeV/c μ - G4Beamline model of D2 beam line Geometrical Acceptance:40 msr （ point source ） Yield: 4.4 counts/pulse/100-kW @ detector → 5 × 10 9 /sec/MW in the Muon Production Target. Geant4 MC: 7 × 10 9 /sec/MW for SiC Rotation target: 10 10 /sec/MW

67. 67 Jaap ’ s H-line Design muonium branchg-2 branch

69. 69 kicker no hits / 10 9 total protons -> extinction < 10 -9 Statistics Limited extinction < 6 x 10 -7 limited by BG from muon decay outside delayed fluorescence from the plastic scintillator Some Experimental Observations

70. DeeMe @ J-PARC MLF mu-e conversion SensitivitySchedule DeeMe~10 -14 ~2015 COMET<10 -16 2017~ DeeMe does not replace COMET. DeeMe will gain momentum of muon-CLFV research field. Sound scenario to secure the world-first discovery.