PSI でのミューオン実験 Muon Experiment at the PSI 西口 創 , KEK 素核研 RCNP 研究会「ミューオン科学と加速器研究」 , 23-24.Feb.2010, 大阪大学 RCNP
2 Contents ✤ PSI ? ✤ Muon Beam Line in PSI ✤ Muon Experiment in PSI ✤ past / present (MEG) ✤ Future Prospects in PSI Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
PSI ?
4 PSI : Paul Scherrer Institut ✤ Largest Swiss Federal Institute for a lot of Scientific research activities. ✤ Mainly based on “ proton cyclotron ” and “ nuclear reactor ” because this institute was merged by two institutes in 1988: ✤ SIN : Swiss Institute for Nuclear Research PSI ✤ EIR : Federal Institute for Reactor Research ✤ something similar with combination of KEK and JAEA in Japan ✤ PSI is a member of ETH domain (ETHZ, EPFL); for not only Particle- Nuclear but also Structure of Matter, Energy & Environment, and Health. ✤ However, according to its prestigious history of powerful cyclotron, PSI is still referred as “ Mecca of Meson Factory ” like TRIUMF, LAMPF, RAL. Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
5 PSI and its Cyclotron Facility Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
6 PSI Proton Cyclotron ✤ The cyclotron facility contains a cascade of three accelerators that deliver a proton beam of 590 MeV energy at a current up to 2 mA (1.2 MW) . ✤ Pre-accelerated in a C-W column to an energy of 870 keV, secondary- accelerated in the 4-sector Injector 2 cyclotron up to 72 MeV. ✤ Final acceleration of the main beam to 590 MeV occurs in the large 8- sector Ring Cyclotron, from which the beam is transported through the experimental hall in a shielded tunnel. Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
7 Experimental Facility with 2nd-beamlines ✤ The main beam passes through two pion production targets isotope prod. whereby the proton energy is reduced to 570 MeV. π M1 μ E4 ✤ Target-M (5mm C) π E1 ✤ Target-E (40mm C) ✤ After passing through the targets the beam can either be dumped in a beam stopper or can be μ E1 recaptured and bent downwards π M3 π E5 through a sloping drift tube for onward transport to the SINQ- π E3 facility. proton therapy Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
Muon Beamline
9 As a “ Meson Factory ” ✤ PSI provides beam time for particle physics and other experiments. Its unique specialty is very high intensity pion and muon beams of momenta up to a few hundred MeV/ c . ✤ Each beam line is designed for “surface”, “subsurface”, “cloud”, and “low-E μ SR” muons, except for π M1. ✤ The world most intense DC muon beam (~10 8 muon/sec) is available. ✤ Two target station, M (thin, 5 mm C) and E (thick, 40/60 mm C), are equipped; Two beam lines are attached with Target-M and Five beam lines are attached with Target-E. ✤ One beam line is used for test beam purpose, Three beam lines are exclusively used for μ SR, and Three beam lines are used for Particle/ Nuclear Physics experiments. Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
10 Target-M; π M1 and π M3 ✤ π M1 beam line ✤ π M3 beam line ✤ High resolution pion beam line ✤ Currently the only beam line with a momentum range dedicated exclusively to μ SR between 100 and 500 MeV/c. experiments with "surface" muons ✤ The beam line contains an ✤ A 3 m long crossed-field electrostatic separator built at CERN, which can reduce the separator can be used either as proton contamination in a π + an electron/muon separator or beam from 400% to about 5% at as a muon spin rotator. 300 MeV/c momentum. ✤ After the separator the beam ✤ No "surface" muons available. can be steered into one of two experimental areas; Low ✤ Mainly used for the test-beam temperature facility LTF and a purposes. general purpose system GPS for μ SR studies is installed. Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
11 Target-E; π E1, π E3, π E5, μ E1 and μ E4 Seco Secondary Beam lines with Thick Targ Target Station “E” Was used by PiBeta. High intensity pi/mu with momentum ranging π E1 10-500 MeV/c. Surface muon is available. Is being used by PEN. Was used by Many muon programs. High intensity pi/mu with momentum ranging π E3 Is being used by MuSun, and being 10-250 MeV/c. Surface and Cloud muons. modified for high-B muSR. High intensity low momenta pi/mu ranging 10-120 Was used by SINDRUM. π E5 MeV/c. The most intense surface muon. Is being used by MEG/LambShift For an intense medium energy polarized muon μ E1 Dedicated for μ SR beam, very low pion/electron contamination. Large acceptance beam line for low momenta muon μ E4 Dedicated for μ SR (<40MeV/c), specially designed for Low-E μ SR Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
μ Experiments
13 Past Pion/Muon Experiments in PSI ✤ PSI has born the burden of fundamental physics for many decades; in particular precise measurement of pion and muon properties. ✤ Recently completed programs: ✤ Muonium-AntiMuonium conversion (MM) ✤ Search for Heavy Neutral Particle (KARMEN) ✤ Muon-Electron Conversion (SINDRUM-II) ✤ Improved Measurement of Charged Pion Mass ✤ T-violation in Muon decay ✤ Pion Beta-decay (PiBeta) ✤ Pionic Hydrogen ✤ (developments) Large Acceptance Detector System (LADS) ✤ (developments) F/B muon spectrometer at L3 ✤ (developments) Central Silicon Tracker at H1 Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
14 Active Particle Physics Experiments in PSI ✤ MEG and nEDM : Flagship Projects in Particle Physics Division ✤ MuCap : Singlet Muon Capture on the Proton ✤ nTRV : Decay of Free Polarized Neutron ✤ LambShift in Muonic Hydrogen : to eliminate the contribution of the proton charge radius ✤ MuLan : τ μ measurement (Improving the precision of G F ) ✤ FAST : τ μ measurement (Improving the precision of G F ) ✤ PEN : Improving the accuracy of the π → e ν branching ratio. ✤ MuSun : Muon Capture on the Deuterium ✤ Detector Developments : Pixel barrel and ECAL for CMS Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
15 MEG Experiment ✤ Search Experiment for “ μ → e γ ” ✤ μ → e νν ～ 100% (normal muon decay in SM) ✤ μ → e γ violates Lepton Flavour Conservation ✤ Even assuming “SM” + “Neutrino-Oscillation” B ( μ → e γ ) is assumed < 10 -50 ✤ Many models of beyond SM, however, predicts large B ( μ → e γ ) ～ 10 -15 ～ -11 ✤ New experiment with a Sensitivity of B ~ 10 -13 was proposed at PSI ✤ Two orders of magnitude better than current best limit (1.2 × 10 -11 ) ✤ Cover the most of theoretically predicted region ✤ Physics data-taking started 2008 and is currently running. Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
16 Hunting for μ → e γ ✤ Signal and Backgrounds Accidental BG. Prompt BG. Signal ✤ Clear 2-body kinematics ( E e = E γ =52.8MeV, θ e γ =180°, Time Coincidence) ✤ Sensitivity is Limited by “Accidental Overlap” How about in MUSIC ??? ✤ DC muon is the Best Solution ✤ Good Resolution (Energy, Spacial and Timing) under Very High Rate Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
17 Features of MEG ✤ The world most intense DC muon beam ✤ ~ 10 8 muon/sec at π E5 ✤ Liquid-Xenon photon detector σ γ -ray from ✤ Excellent Resolutions (E: 2%, T: ~70ps, X: ~5mm) muon decay ✤ Fast Response (Good for pile-ups) σ ✤ Uniform, Segment is not necessary σ 1m ✤ Specially Degraded Magnetic Spectrometer ✤ Possible in 10 8 /sec intensity ✤ Very Light Tracker (0.002 X 0 in total) ✤ Very Fast Hodoscope array (~120ps) Hajime NISHIGUCHI ( KEK ) “ Muon Experiment at PSI” 「 RCNP 研究会 : ミューオン科学と加速器研究」 , 23-24.Feb.2010, RCNP
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