Muon - Electron Conversion at J-PARC COMET-PRISM/PRIME
description
Transcript of Muon - Electron Conversion at J-PARC COMET-PRISM/PRIME
U H M E P
PRISM/PRIME
COMET
Muon - Electron Conversion at J-PARC
COMET-PRISM/PRIME
Ed HungerfordUniversity 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, UKImperial College London, UK A. Kurup, J. Pasternak, Y. Uchida,A. Kurup, J. Pasternak, Y. Uchida, P. Dauncey, U. Egede, P. P. Dauncey, U. Egede, P. Dornan,Dornan, and L. Jennerand L. JennerUniversity College London, University College London, UKUK 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, Department of physics and astronomy, University of British Columbia, Vancouver, University of British Columbia, Vancouver, CanadaCanada D. Bryman D. Bryman TRIUMF, CanadaTRIUMF, Canada T. NumaoT. Numao
43 people from 13 institutes ( 25th May 2009 )
Department of Physics, Department of Physics, Brookhaven National Laboratory, USABrookhaven National Laboratory, USA R. PalmerR. PalmerY. Cui Y. Cui Department of Physics, University of Department of Physics, University of Houston, USAHouston, USA E. Hungerford E. HungerfordK. LauK. Lau
5/30/09 Ed Hungerford for the COMET collaboration 2
Institute for Chemical Research, Kyoto University, Institute for Chemical Research, Kyoto University, Kyoto, JapanKyoto, Japan Y. Iwashita,Y. Iwashita,Department of Physics, Osaka University, JapanDepartment of Physics, Osaka University, Japan M. Aoki, Md.I. Hossain, T. Itahashi, Y. Kuno, N. Nakadozono*, M. Aoki, Md.I. Hossain, T. Itahashi, Y. Kuno, N. Nakadozono*, A. Sato, T. Tachimoto* and M. YoshidaA. Sato, T. Tachimoto* and M. YoshidaDepartment of Physics, Saitama University, JapanDepartment of Physics, Saitama University, Japan M. Koike and J. SatoM. Koike and J. SatoDepartment of Physics, Tohoku University, JapanDepartment of Physics, Tohoku University, Japan Y. Takubo,Y. Takubo,High Energy Accelerator Research Organization (KEK), High Energy Accelerator Research Organization (KEK), JapanJapan Y. Arimoto, Y. Igarashi, S. Ishimoto, S. Mihara, H. Y. Arimoto, Y. Igarashi, S. Ishimoto, S. Mihara, H. Nishiguchi, Nishiguchi, T. Ogitsu, M. Tomizawa, A. Yamamoto, and K. YoshimuraT. Ogitsu, M. Tomizawa, A. Yamamoto, and K. YoshimuraInstitute for Cosmic Ray Research, JapanInstitute for Cosmic Ray Research, Japan M. YamanakaM. Yamanaka
JINR, Dubna, RussiaJINR, Dubna, Russia V. Kalinnikov, A. Moiseenko, V. Kalinnikov, A. Moiseenko, D. Mzhavia, J. Pontecorvo, D. Mzhavia, J. Pontecorvo, B. Sabirov, Z. Tsamaiaidze, B. Sabirov, Z. Tsamaiaidze, and P. Evtukhouvichand P. Evtukhouvich
U H M E P
PRISM/PRIME
COMET Muon-to-Electron (μ-e) Conversion Lepton Flavor Violation
Muonic Atom
nucleus
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 Conversionμ- + A →e-+ A
Nuclear Capture μ- + A →ν+ [N +(A-1)]
U H M E P
PRISM/PRIME
COMET Introductionto
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 0.5x10-1610-18
• 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 2009. 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.
COMETAl Target
SINDRUM
Signal at`muon mass
DIO
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) 046.
5/30/09 Ed Hungerford for the COMET collaboration 6
Present Sindrum Limit
B(μ → e + )10-13
B(μ + Al → e + Al) < 10-16COMET
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
05-30-09 Ed Hungerford
for the COMET collaboration
8
• Electron ResolutionMinimal Detector Material – Thin, Low Z Vacuum EnvironmentREDUNDENT measurements of the electron track
• RatesUp to 500 kHZ single ratesLarge channel countR/O timing (~1-2ns) and analog information
• Dynamic Range Protons 30-40 times Eloss for MIP Pileup and saturation Maintain MIP track efficiency
• Low-Power, Low-foot print electronicsHeatSignal Transmission, inside-to -outside the vacuumNoise
• REDUNDANCY Redundancy (Redundancy, Redundancy, Redundancy) Ambiguous hits, dead channels, accidentalsReconstruction 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
Early Realization Phase II
U H M E P
PRISM/PRIME
COMET J-PARCJapan 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-Phase2PRISM-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
Background Challenge beam intensity
• μ→eγ accidentals detector resolution limited
• μ-e conversion beam beam
background Less 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 10-14 (with a run of 108/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 1011 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
Backgrounds Events Comments
(1)
Muon decay in orbitRadiative muon captureMuon capture with neutron emissionMuon capture with charged particle emission
0.05<0.001<0.001<0.001
230 keV resolution
(2)
Radiative pion capture*Radiative pion captureMuon decay in flight*Pion decay in flight*Beam electrons*Neutron induced*Antiproton induced
0.120.002<0.02
<0.0010.08
0.0240.007
promptlate arriving pions
for high energy neutronsfor 8 GeV protons
(3) Cosmic-ray inducedPattern recognition errors
0.10<0.001
10-4 veto efficiency
Total 0.4
U H M E P
PRISM/PRIME
COMET
Signal Sensitivity
• Single event sensitivity Nμ is a number of stopping
muons in the muon stopping target which is 6x1017 muons.
– fcap is a fraction of muon capture, which is 0.6 for aluminum.
– Ae is the detector acceptance, which is 0.07.
total protonsmuon transport efficiencymuon stopping efficiency
8x1020
0.00710.26
# of stopped muons 1.5x1018
5/30/09 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 10-16
• 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 10-18. 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
04/24/23 18
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, PT=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 22
16 Wire Units 5 mm Wire spacing 208 wires/array832 wires/plane4160 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
FE ASIC
AnalogBuffer
ADC
LocalReadoutControl
(in CPLD)
W Section SectionReadoutControl(FPGA)
PlaneReadoutControl
Off-lineDatabase
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 (Pμ>75 MeV/c)
• Straight + curved solenoid transport system to select momentum and charge
5/30/09 Ed Hungerford for the COMET collaboration 25