An Expression of Interest for Phase-I of the COMET Experiment at J-PARC

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An Expression of Interest for Phase-I of the COMET Experiment at J-PARC We hereby express our interest to stage the construction of the COherent Muon to Electron Transition (COMET) experiment that

4 An Expression of Interest for Phase-I of the COMET Experiment at J-PARC We hereby express our interest to stage the construction of the COherent Muon to Electron Transition (COMET) experiment that will search for neutrinoless µ e conversions with a single-event sensitivity of This sensitivity is a factor of 1, better than achieved by the SINDRUM-2 experiment which has set the world s best limit for µ e conversions. The COMET experiment was given stage-1 approval by the J-PARC Program Advisory Committee in 29 and is now J-PARC E21. The proposed J-PARC mid-term plan includes the construction of the COMET beamline. This will provide the proton beamline for COMET and part of the muon beamline in the south area of the J-PARC Hadron Experimental Hall. We consider a staged approach for COMET as described below. To realise this staged approach we would like to construct the muon beamline up to the end of the first 9 bend in the muon beamline so that a muon beam can be extracted to the experimental area. We call this COMET Phase-I. In COMET Phase-I, we will 1. make a direct measurement of the proton beam extinction and other potential background sources for the full COMET experiment, using the actual COMET beamline; and 2. carry out a search for µ e conversion with a sensitivity better than achieved by SINDRUM-2.

6 COMET Phase-I LoI MUON TRANSPORT Pion production target Radiation shield Proton beam Capture solenoid Matching solenoid μ-e conversion Beam Study COMET Solenoids and Detector for the CDR version Muon beam transport solenoid Late-arriving particle tagger Beam collimator Muon stopping target Beam blocker DIO blocker search Muon target solenoid Calorimeter Tracker Curved sepctrometer solenoi Detector solenoid Figure 5.14: Present design of the solenoid channel used in the tracking studies Dipole fields for drift compensation

9 Momentum (Me 8 6 am optics of curved solenoids 4 Momentum (Me It is known that in a Y (cm) momentum selection 2 of beam particles can be 2performed using curved enoids, -2-1which introduce dispersion into 1 2the beam Y (cm) Y (cm) Y (cm) Y (cm) Y (cm) Momentum (Mev/c) 8 Entries Y = (cm) Y (cm) qb.135t,.225t xis, and s [m] and R [m] are the path length andall the particles radius of curvature Entries all particles pion- pionmuon- solenoid, respectively. Here, s/r(= θ 5 1 electron- pion+ muon+ ersion of negative muons (momentum bend )isthebendingangleθ muon- vs. vertical (y) bend and position) at electron+ electron- pion+ and transverse the neutrons protons ional kaon+ 5 kaonhelium-3 triton to θ bend,andp L and p T [GeV/c] are the longitudinal bend. muon+ 4 deuteron gamma spectively. 1 other particles The pitch angle of the helical trajectory electron+ is represented by θ id, the center of the -2 helical -1 trajectory 1 of2 Y (cm) Y (cm) a charged -2 particle -1 drifts 1in Y (cm) a 2 di- Momentum vs Y for muon- at blt Momentum Momentum vs Y for vs muon+ Y for muon- at blt at blt Momentum Momentum vs Y for vs muon+ Y for muon- at blt at blt Momentum vs Y for muon+ at blt s perpendicular 1 to plane 1 1 containing the curved 1 solenoid. 1 The magnitude 1 of is, given.225t by Momentum (.135T,.225T T,.275T Momentum (Mev/c) Entries Entries D = 1 6 ( s ) p 2 L p2 6 6 T 4, (4.1) 2 qb 2R p of negative muons 2 L 2 )(momentum ( p cos θ + 1 ) vs. vertical (Y )position)atth Y (cm), Y (cm) (4.2) d. Momentum (M Momentum (Mev/c) ( s R.165T,.275T cos θ 3 1 omentum selection if a suitable collimator is placed after kaonhelium-3 the curved solenoid. onal vertical dipole field can be applied in ordertriton to maintain 2 along the Momentum (Me Momentum (Mev/c) Entries Entries T,.3T.165T,.18T,.275T.3T e electric charge of the particle (including its sign), B [T] is the magnetic icles with opposite signs drift in opposite directions. protons This can be used for entum distribution 1 4 deuteron gamma is the centers of the helical trajectories of the muons other particles that have a specific. The magnitude of this compensating dipole field is given by Momentum (M Momentum (Mev/c) Momentum ( 6 4 Ben Krikler 9 Imperial College Lo Entries neutrons kaon+ Y (cm) Momentum (M Momentum (Mev/c) Entries Y (cm).18t,.3t Momentum, p (MeV/c)

10 An:proton' stopper Cryo8cooler Detector' Vacuum' Vessel Sensor'feedthru Signal'readout'& Voltage'supply' feedthru'port Muon%Transport%Solenoid Spectrometer%Solenoid Vacuum'port Strawtube' Tracker Crystal' Calorimeter' Array

12 µ

14 µ +(A,Z) e +(A,Z) à µ µ à e ν ν µ + ( A, Z) à ν µ + (A,Z 1) B(µ N e N) = Γ (µ N à e N) à Γ ( µ N à νn ' )

Λ (TeV) B(µ e conv in 48 Ti)>1-18 1 4 B(µ e conv in 48

15 Λ (TeV) B(µ e conv in 48 Ti)> B(µ e conv in 48 Ti)>1-16 B(µ eγ)>1-14 B(µ eγ)> EXCLUDED κ

µe2ν simulation µe simulation at B=1-11 Figure 3.

16 capture in the moderator (see also Fig.3.1 and the discussion in the text). events / 1 kev SINDRUM II run2 on gold ETOT (MeV) SINDRUM II measurement µe2ν simulation µe simulation at B=1-11 Figure 3.3: The measured energy distribution is compared with simulated distributions for muon decay in orbit and µe conversion. No events are found above 1 MeV L

18 An:proton' stopper Cryo8cooler Detector' Vacuum' Vessel collimator Sensor'feedthru Signal'readout'& Voltage'supply' feedthru'port Muon)Transport)Solenoid Vacuum'port Spectrometer)Solenoid Strawtube' Tracker Crystal' Calorimeter' Array

20 LoI_monitor45-mu_n-p.pdf pµ- (MeV/c) pµ- (MeV/c) LoI_monitor45-mu_n-dispersion.pdf LoI_monitor45-mu_n-t.pdf Timeµ- (µ s) 1 Beam Simulation 年月 2 4 日土曜日 LoI_monitor45-mu_n-p.pdf pµ- (MeV/c) pµ- (MeV/c) LoI_monitor45-mu_n-dispersion.pdf LoI_monitor45-mu_n-t.pdf CHAPTER 4. MUON BEAM Timeµ- (µ s) AMFigure 4.6: Profile of negative muons before and after the 35 beam collimator. (production) & g4beamline (simulation) AMFigureMars : Profile of negative muons before and after the beam collimator. monitor21: before the collimator collimator Tosca (B ﬁeld) 日土曜日 collimatormonitor21: before the collimator 7 14 (MeV/c) (count) μ pπ- (MeV/c) pµ- (MeV/c) LoI_monitor21-pi_n-p.pdf LoI_monitor21-mu_n-dispersion.pdf π pπ- (MeV/c) - (µ s) Time µ LoI_monitor21-pi_n-dispersion.pdf LoI_monitor21-mu_n-t.pdf Time 12- (µ s) 14 µ p (MeV/c) (MeV/c) p (MeV/c) p (MeV/c) ollimator (before the stopping target) monitor45: after the collimator (before the stopping target) LoI_monitor21-mu_n-dispersion.pdf LoI_monitor21-mu_n-t.pdf LoI_monitor21-pi_n-p.pdf LoI_monitor21-pi_n-dispersion.pdf µ- π - π after collimation Total momentum for at monitor45 Total momentum vs Y for µ atπ-monitor45 - Total momentum Y for π- at monitor45 Arrival time for µ - atvs monitor (MeV/c) 14 (MeV/c) Total momentum vs Y for µ at monitor Total momentum for π at monitor (count) y (mm) 日土曜日 8 6 y(count) (mm) LoI_monitor45-mu_n-dispersion.pdfp (MeV/c) Number of all muons = 7744 Number of stopped muons = 2653 Stopping efficiency =.344 (count) LoI_monitor21-pi_n-t.pdf 1 Timeπ- (µ s) LoI_monitor21-pi_n-t.pdf 2 Timeπ- (µ s) Arrival time for π- at monitor pµ- (MeV/c) pµ- (MeV/c) 16 of particles / proton (x1-3) 1 # 14 8 all 12 6 Figure 4.8: Momentum distribution of muons.23% comingstop to the muo stop μμ/ spectrum in red is a fraction of muons stopped in the muon stop proton high-p μ Time (µ s) -1 p (MeV/c) 4 Time (µ s) negative π LoI_monitor45-mu_n-t.pdf LoI_monitor45-pi_n-dispersion.pdf LoI_monitor45-pi_n-t.pdf Time 12 (µ s) Arrival time for µ at monitor45 π pµ- (MeV/c) 5 pπ- (MeV/c) LoI_monitor45-mu_n-dispersion.pdf LoI_monitor45-pi_n-p.pdf 5 2 年月 7 1 Total momentum vs Y for π at monitor (count) y (mm) (count) y (mm) μ - - Arrival time for π- at monitor45 llimator 15(before the stopping monitor45: after the target) collimator (before the stopping target) 25 stopped 5 All µtime momentum just before stopping targets Arrival for π at monitor21 7 Arrival timemomentum for µ - at monitor21 Total vs Y for π- at monitor21 μ- on the target 6 (count) (µ- / protons / MeV/c) (count) 8 (count) y (mm) 6 Arrival time for π- at monitor21 2 (count) y (mm) (count) y (mm) 2 Total momentum vs Y for π- at monitor21 Arrival time for µ - at monitor21 Total momentum vs Y for µfor atπmonitor21 Total momentum at monitor21 y (mm) before collimation Total momentum for π- at monitor21 Total momentum vs Y for µ - at monitor π- 1 (count) 年月 µ- 2 π LoI_monitor45-mu_n-t.pdf µ- p (MeV/c) Time - (µ s)

3 2 1 1 Proton Emission after Muon Capture All Events (Entries 1) Hitting

Entries 54187 Mean 13.6 RMS.976 11 11.5 12 12.5 13 13.5 14 14.5 15 15.

21 Proton Emission after Muon Capture All Events (Entries 1) Hitting Innermost Layer (Entries 95) MeV/c Fitted Momentum Entries Mean 13.6 RMS MeV/c Fitted Momentum Entries Mean 11.7 RMS MeV/c

B(µ + Al e + Al) = 1 Nµ stop f cap A µ-e Integral over Eth 1.2 1.8.6.4.2 99 1 11 12 13 14 15 Eth (kev) Event selection Value Comments Geometrical acceptance.

22 B(µ + Al e + Al) = 1 Nµ stop f cap A µ-e Integral over Eth Eth (kev) Event selection Value Comments Geometrical acceptance.4 tracking efficiency included Momentum selection.66 P e >11.9 MeV/c Timing selection.39 same as COMET Trigger and DAQ.9 same as COMET Total.9 Signal Acceptance DIO Contamination 5% Contamination 66% Acceptance 11.9keV Energy threshold Background estimated events Muon decay in orbit.5 Radiative muon capture <.1 Neutron emission after muon capture <.1 Charged particle emission after muon capture <.1 Radiative pion capture.24 Beam electrons < 1 Muon decay in flight.4 Pion decay in flight <.1 Neutron induced background.24 Delayed radiative pion capture.2 Anti-proton induced backgrounds.7 Cosmic ray muons.1 Electrons from cosmic ray muons.1 Total.11

23 Signal'readout'& Voltage'supply' feedthru'port Vacuum'port Sensor'feedthru Cryo8cooler An:proton' stopper Spectrometer)Solenoid Crystal' Calorimeter' Array Strawtube' Tracker Detector' Vacuum' Vessel Muon)Transport)Solenoid collimator

24 Beam,Switch,Yard A&line&!&3&GeV& B&line&!&8~3&GeV& T1&target&to&provide&secondary&beam B2line&branch&from&A&line COMET&&&High2p&line&switch COMET&pion&producOon&target Secondary& Beam&lines& COMET& Experiment Experimental,Hall High2p&Beam&line& COMET, Experimental,Hall High2p& Beam&Dump 75kW& Beam&Dump &COMET& Beam&dump

26 Budget KEK External Optional Future Comments request internal funding funding Building 8. Beam 1..5 dump SC 8. to first 9 o bend magnet 2. remaining beam line Wshield 2. for higher power Power 2. if purchased supply.5 installation 2.5 for upgrade refrig- 2. if constructed erator.5 installation Beam magnet.5 installation line 5. for higher power piping.3.3 cabling.6.6 vacuum.6.6 Radiation NP-hall 1.5 for 3 kw operation shielding 6.5 for high power Safety.5 π target.8 experimental group Detector magnet.5.5 for Phase-I µ target.1 experimental group µ monitor 1.5 experimental group tracker 1.1 experimental group ECAL 1.6 experimental group CR veto 5.7 experimental group DAQ.5 experimental group Total

27 R. Akhmetshin, A. Bondar, L. Epshteyn, G. Fedotovich, D. Grigoriev, V. Kazanin, A. Ryzhenenkov, D. Shemyakin, Yu. Yudin Budker Institute of Nuclear Physics (BINP), Novosibirsk, Russia Y.G. Cui, R. Palmer Department of Physics, Brookhaven National Laboratory, USA Y. Arimoto, K. Hasegawa, Y. Igarashi, M. Ikeno, S. Ishimoto, Y. Makida, S. Mihara, T. Nakamoto, H. Nishiguchi, T. Ogitsu, C. Omori, N. Saito, K. Sasaki, M. Sugano, Y. Takubo, M. Tanaka, M. Tomizawa, T. Uchida, A. Yamamoto, M. Yamanaka, M. Yoshida, Y. Yoshii, K. Yoshimura High Energy Accelerator Research Organization (KEK), Tsukuba, Japan Yu. Bagaturia Ilia State University (ISU), Tbilisi, Georgia P. Dauncey, P. Dornan, B. Krikler, A. Kurup, J. Nash, J. Pasternak, Y. Uchida Imperial College London, UK P. Sarin, S. Umasankar Indian Institute of Technology Bonbay, India Y. Iwashita Institute for Chemical Research, Kyoto University, Kyoto, Japan V.V. Thuan Institute for Nuclear Science and Technology, Vietnam H.-B. Li, C. Wu, Y. Yuan Institute of High Energy Physics (IHEP), China A. Liparteliani, N. Mosulishvili, Yu. Tevzadze, I. Trekov, N. Tsverava Institute of High Energy Physics of I.Javakhishvili State University (HEPI TSU), Tbilisi, Georgia S. Dymov, P. Evtoukhovich, V. Kalinnikov, A. Khvedelidze, A. Kulikov, G. Macharashvili, A. Moiseenko, B. Sabirov, V. Shmakova, Z. Tsmalaidze Joint Institute for Nuclear Research (JINR), Dubna, Russia M. Danilov, A. Drutskoy, V. Rusinov, E. Tarkovsky Institute for Theoretical and Experimental Physics (ITEP), Russia T. Ota Max-Planck-Institute for Physics (Werner-Heisenberg-Institute), Munchen, Germany Y. Mori, Y. Kuriyama, J.B. Lagrange Kyoto University Research Reactor Institute, Kyoto, Japan C.V. Tao College of Natural Science, National Vietnam University, Vietnam M. Aoki, T. Hiasa, I.H. Hasim T. Hayashi, Y. Hino, S. Hikida, T. Itahashi, S. Ito, Y. Kuno, T.H. Nam, H. Nakai, H. Sakamoto, A. Sato, N.D. Thong, N.M. Truong Osaka University, Osaka, Japan M. Koike, J. Sato Saitama University, Japan D. Bryman University of British Columbia, Vancouver, Canada S. Cook, R. D Arcy, A. Edmonds, M. Lancaster, M. Wing University College London, UK E. Hungerford University of Houston, USA W.A. Tajuddin University of Malaya, Malaysia R.B. Appleby, W. Bertsche, M. Gersabeck, H. Owen, C. Parkes University of Manchester, UK F. Azfar University of Oxford, UK Md. Imam Hossain University Technology Malaysia 3 T. Numao TRIUMF, Canada

COMET Satoshi MIHARA IPNS, KEK

COMET Satoshi MIHARA IPNS, KEK Outline clfv search experiment COMET at J-PARC Physics Goal Requirement Summary clfv Search Experiments muon g-2 Neutrino Oscillation Higgs boson New Physics BSM clfv Search