U H M E P PRISM/ PRIME COMET Muon - Electron Conversion at J-PARC COMET-PRISM/PRIME Ed Hungerford University of Houston for the COMET Collaboration 5/30/09 Ed Hungerford for the COMET collaboration 1

U H M E P PRISM/ PRIME COMET Imperial College London, UK A. Kurup, J. Pasternak, Y. Uchida, P. Dauncey, U. Egede, P. Dornan, P. Dauncey, U. Egede, P. Dornan, and L. Jenner and L. Jenner University College London, UK M. Wing, M. Lancaster, M. Wing, M. Lancaster, and R. D’Arcy* and R. D’Arcy* Imperial College London, UK A. Kurup, J. Pasternak, Y. Uchida, P. Dauncey, U. Egede, P. Dornan, P. Dauncey, U. Egede, P. Dornan, and L. Jenner and L. Jenner University College London, UK M. Wing, M. Lancaster, M. Wing, M. Lancaster, and R. D’Arcy* and R. D’Arcy* The COMET-PRISM Collaboration 2 Department of physics and astronomy, University of British Columbia, Vancouver, Canada D. Bryman TRIUMF, Canada T. Numao Department of physics and astronomy, University of British Columbia, Vancouver, Canada D. Bryman TRIUMF, Canada T. Numao 43 people from 13 institutes ( 25th May 2009 ) Department of Physics, Brookhaven National Laboratory, USA R. Palmer Y. Cui Department of Physics, University of Houston, USA E. Hungerford K. Lau Department of Physics, Brookhaven National Laboratory, USA R. Palmer Y. Cui Department of Physics, University of Houston, USA E. Hungerford K. Lau 5/30/09 Ed Hungerford for the COMET collaboration 2 Institute for Chemical Research, Kyoto University, Kyoto, Japan Y. Iwashita, Department of Physics, Osaka University, Japan M. Aoki, Md.I. Hossain, T. Itahashi, Y. Kuno, N. Nakadozono*, A. Sato, T. Tachimoto* and M. Yoshida A. Sato, T. Tachimoto* and M. Yoshida Department of Physics, Saitama University, Japan M. Koike and J. Sato Department of Physics, Tohoku University, Japan Y. Takubo, High Energy Accelerator Research Organization (KEK), Japan Y. Arimoto, Y. Igarashi, S. Ishimoto, S. Mihara, H. Nishiguchi, T. Ogitsu, M. Tomizawa, A. Yamamoto, and K. Yoshimura T. Ogitsu, M. Tomizawa, A. Yamamoto, and K. Yoshimura Institute for Cosmic Ray Research, Japan M. Yamanaka M. Yamanaka Institute for Chemical Research, Kyoto University, Kyoto, Japan Y. Iwashita, Department of Physics, Osaka University, Japan M. Aoki, Md.I. Hossain, T. Itahashi, Y. Kuno, N. Nakadozono*, A. Sato, T. Tachimoto* and M. Yoshida A. Sato, T. Tachimoto* and M. Yoshida Department of Physics, Saitama University, Japan M. Koike and J. Sato Department of Physics, Tohoku University, Japan Y. Takubo, High Energy Accelerator Research Organization (KEK), Japan Y. Arimoto, Y. Igarashi, S. Ishimoto, S. Mihara, H. Nishiguchi, T. Ogitsu, M. Tomizawa, A. Yamamoto, and K. Yoshimura T. Ogitsu, M. Tomizawa, A. Yamamoto, and K. Yoshimura Institute for Cosmic Ray Research, Japan M. Yamanaka M. Yamanaka JINR, Dubna, Russia V. Kalinnikov, A. Moiseenko, D. Mzhavia, J. Pontecorvo, D. Mzhavia, J. Pontecorvo, B. Sabirov, Z. Tsamaiaidze, B. Sabirov, Z. Tsamaiaidze, and P. Evtukhouvich and P. Evtukhouvich JINR, Dubna, Russia V. Kalinnikov, A. Moiseenko, D. Mzhavia, J. Pontecorvo, D. Mzhavia, J. Pontecorvo, B. Sabirov, Z. Tsamaiaidze, B. Sabirov, Z. Tsamaiaidze, and P. Evtukhouvich and P. Evtukhouvich

U H M E P PRISM/ PRIME COMET Muon-to-Electron (μ-e) Conversion Lepton Flavor Violation Muonic Atom 5/30/09 Ed Hungerford for the COMET collaboration 3 μ Decay in Orbit (DIO) μ - → e - ν ν Lepton Flavor Changes by one unit Coherent Conversion μ - + A →e - + A Nuclear Capture μ - + A →ν+ [N +(A-1)]

U H M E P PRISM/ PRIME COMET Introduction to COMET-PRISM/PRIME COMET (Phase I)  PRISIM/PRIME (Phase II) is a search for coherent, neutrino-less conversion of muons to electron ( μ-e conversion) at a single sensitivity of 0f 0.5x  The experiment offers a powerful probe for new physics beyond the Standard Model. It will be undertaken at J-PARC. Phase I (COMET) uses a slow-extracted, bunched 8 GeV proton beam from the J-PARC main ring. A proposal was submit to J-PARC Dec. 2007, and a Conceptual Design Report submitted June COMET now has Stage-1 approval from the J-PARC PAC (July 2009). The Collaboration is completing R&D for a TDR. 5/30/09 Ed Hungerford for the COMET collaboration 4

U H M E P PRISM/ PRIME COMET The SINDRUM-II Experiment (at PSI) Published Results 5/30/09 Ed Hungerford for the COMET collaboration 5 SINDRUM-II used a continuous muon beam from the PSI cyclotron. To eliminate beam related background from the beam, a beam-veto counter was used. This technology cannot be used with higher beam rates in modern beamlines. COMET Al Target SINDRUM Signal at `muon mass DIO

U H M E P PRISM/ PRIME COMET Sensitivities SUSY-Seesaw Model ( SUSY-GUT SO(10) ) A.Masiero et al., J. High Energy Phys. B.JHEP03, (2004) /30/09 Ed Hungerford for the COMET collaboration 6 Present Sindrum Limit B(μ → e +  ) B(μ + Al → e + Al) < COMET PRISM

U H M E P PRISM/ PRIME COMET Prediction from SUSY-SU(5) 5/30/09 Ed Hungerford for the COMET collaboration 7 Tan(  ) = ( h2/ h1) ;  = higgsino mass J. Hisano, T. Moroi, K. Tobe and M. Yamaguchi, Phys. Lett. B 391, 341 (1997)

U H M E P COMET Ed Hungerford for the COMET collaboration 8 Electron Resolution Minimal Detector Material – Thin, Low Z Vacuum Environment REDUNDENT measurements of the electron track Rates Up to 500 kHZ single rates Large channel count R/O timing (~1-2ns) and analog information Dynamic Range Protons times Eloss for MIP Pileup and saturation Maintain MIP track efficiency Low-Power, Low-foot print electronics Heat Signal Transmission, inside-to -outside the vacuum Noise REDUNDANCY Redundancy (Redundancy, Redundancy, Redundancy) Ambiguous hits, dead channels, accidentals Reconstruction of ghost tracks Robust measurements Design Considerations for COMET (and generally all) μ to e Experiments

U H M E P PRISM/ PRIME COMET COMET  PRISM at J-PARC 5/30/09 Ed Hungerford for the COMET collaboration 9 COMET Modification of MECO/MELC Requires a slow-extracted, pulsed -beam Proposed for the J-PARC NP Hall. Regarded as phase I - Early realization Early Realization Phase II PRISM Needs a muon storage ring. Requires a fast-extracted, pulsed-beam. Requires a new beamline and hall. Experience and components of Phase I Extends the reach by 100

U H M E P PRISM/ PRIME COMET J-PARC Japan Proton Accelerator Research Complex 3 GeV Rapid-Cycling Synchrotron, RCS (25 Hz, 1MW ） Hadron Beam Facility NP-Hall Neutrino to Kamiokande 50 GeV Main Ring Synchrotron (0.75 MW) 500 m Linac (330m) PRISM-Phase2 PRISM-Phase1 5/30/09 Ed Hungerford for the COMET collaboration 10

U H M E P PRISM/ PRIME COMET μ→eγ and μ-e Conversion BackgroundChallengebeam intensity μ→eγaccidentalsdetector resolutionlimited μ-e conversion beambeam backgroundLess limited μ→eγ : Accidental background is given by (rate) 2. To push sensitivity the detector resolutions and timing must be improved. However, (in particular for the photon) it would be hard to better MEG with present technology. The ultimate sensitivity is about (with a run of 10 8 /sec). μ-e conversion : 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 used with present timing because no coincidence is required. 5/30/09 Ed Hungerford for the COMET collaboration 11

U H M E P PRISM/ PRIME COMET Overview of COMET 5/30/09 Ed Hungerford for the COMET collaboration 12 Proton Beam The Muon Source Proton Target Pion Capture Muon Transport The Detector Muon Stopping Target Electron Transport Electron Detection

U H M E P PRISM/ PRIME COMET Comparison to MECO Proton Target – tungsten (MECO) – graphite (J-PARC) Muon Transport – Magnetic field distributions are different. – Efficiency of the muon transport is almost the same. Spectrometer – For stopping muons/sec – Straight Solenoid (MECO) ~500 kHz/wire – Curved Solenoid (J-PARC) ~ 300 DIO Hz /detector Detector Wire Planes rather than straws MECO COMET 5/30/09 Ed Hungerford for the COMET collaboration 13

U H M E P PRISM/ PRIME COMET Target and Detector Solenoids a muon stopping target, curved solenoid,tracking chambers, and a calorimeter/trigger and cosmic- ray shields. 5/30/09 Ed Hungerford for the COMET collaboration 14

U H M E P PRISM/ PRIME COMET Background Rejection (preliminary) 5/30/09 Ed Hungerford for the COMET collaboration 15 BackgroundsEventsComments (1) Muon decay in orbit Radiative muon capture Muon capture with neutron emission Muon capture with charged particle emission 0.05 < keV resolution (2) Radiative pion capture* Radiative pion capture Muon decay in flight* Pion decay in flight* Beam electrons* Neutron induced* Antiproton induced <0.02 < prompt late arriving pions for high energy neutrons for 8 GeV protons (3) Cosmic-ray induced Pattern recognition errors 0.10 < veto efficiency Total0.4

U H M E P PRISM/ PRIME COMET Signal Sensitivity S ingle event sensitivity N μ is a number of stopping muons in the muon stopping target which is 6x10 17 muons. – f cap is a fraction of muon capture, which is 0.6 for aluminum. – A e is the detector acceptance, which is total protons muon transport efficiency muon stopping efficiency 8x # of stopped muons1.5x /30/09 Ed Hungerford for the COMET collaboration 16

U H M E P PRISM/ PRIME COMET Summary COMET is a Phase I search for coherent, neutrino-less conversion of muons to electron (μ-e conversion) at a single event sensitivity of The experiment offers a powerful probe for new physics beyond the Standard Model. The experiment will be undertaken at the J-PARC NP Hall using a slowly- extracted, bunched proton beam from the J-PARC main ring. More Advanced design, attempting to reduce backgrounds and miss- constructed electron trajectories The Experiment is developing a TDR and refining design details. The experiment has completed a CDR and has Stage-1 approval of the J-PARC PAC. As a follow-on to COMET, PRISM/PRIME (Phase II) would reach a sensitivity of It requires a new beam line, new hall, and a muon storage ring 5/30/09 Ed Hungerford for the COMET collaboration 17

U H M E P COMET 10/14/ Supplementary Slides

U H M E P PRISM/ PRIME COMET Backgrounds Background rejection is crucial in single-event/few–event searches Avoids statistical separation of events from background Conspiring events can mimic a signal It’s always the background that you don’t predict which imposes the limits - ( Redundancy, Redundancy, Redundancy, ) 5/30/09 Ed Hungerford for the COMET collaboration 19 Intrinsic backgrounds Beam induced on the Stopping Target, Slits and Solenoid Walls muon decay in orbit (DIO) 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 background cosmic rays cosmic-ray pattern recognition errors

U H M E P PRISM/ PRIME COMET The MELC/MECO Proposals Cancelled in 2005 MELC (Russia) MECO (BNL) To eliminate beam related background, beam pulsing was adopted (with delayed measurement). To increase number of muons pion capture in a high-field solenoidal. Curved solenoid used for momentum pre- selection 5/30/09 Ed Hungerford for the COMET collaboration 20 The MECO Experiment at BNL

U H M E P PRISM/ PRIME COMET Pion Capture Solenoid A large muon yield can be achieved by a large solid angle, pion-capture, high- field solenoid surrounding the proton target. B=5T,R=0.2m, P T =150MeV/c. Superconducting Solenoid Magnet for pion capture 15 cm radius bore a 5 tesla solenoidal field 30 cm thick tungsten radiation shield heat load from radiation a large stored energy 5/30/09 Ed Hungerford for the COMET collaboration 21

U H M E P PRISM/ PRIME COMET Electron Detection (preliminary) Wire Plane Trackers for electron momentum Vacuum in constant 1T magnetic field. Straw tube 25μm walls, 5 mm diameter. One plane has 4 views (x,y) + (x’,y’) Five planes are placed 48 cm apart 250μm position resolution. σ = 230 keV/c (multiple scattering dominated.) Electron calorimeter Triggers R/O Redundant Energy Measurement Candidates are GSO or LSO(LYSO). APD readout. 5/30/09 Ed Hungerford for the COMET collaboration Wire Units 5 mm Wire spacing 208 wires/array 832 wires/plane 4160 wires/detector Trigger Calorimeter Wire Plane Tracker ~1.2m

U H M E P PRISM/ PRIME COMET Cosmic Ray Shields Both passive and active shields are used. Passive shields – 2 meter of concrete and 0.5 m of steel Active shields – layers of scintillator veto counters (~1% inefficiency) 5/30/09 Ed Hungerford for the COMET collaboration 23

U H M E P COMET Schematic of System Readout FE ASIC Analog Buffer ADC Local Readout Control (in CPLD) W Section Section Readout Control (FPGA) Plane Readout Control Off-line Database Each plane will have its own data link to send data from the detector. In each plane, the readout sequence is organized in sections. Each section is controlled by a FPGA. Locally, there is a CPLD to control the A-to-D conversion.

U H M E P PRISM/ PRIME COMET Muon Transport Solenoids Muons are transported from the capture section to the detector by the muon transport beamline. Requirements : – long enough for pions to decay to muons (> 20 meters ≈ 2x10 -3 ). – high transport efficiency – negative charge selection – low momentum cut (P μ> 75 MeV/c) Straight + curved solenoid transport system to select momentum and charge 5/30/09 Ed Hungerford for the COMET collaboration 25