124731761
The status of the Superomega muon beamline
The Superomega muon beamline is currently under construction at Experimental hall No. 2 of the Materials and Life Science Facility at J‐PARC in Tokai, Japan. The beamline has a large solid angle acceptance, and will produce the highest intensity pulsed muon beam in the world. The beamline is designed to capture both surface positive and cloud negative muons for simultaneous use in a variety of experiments. The expected rate of surface muons for this beamline is 4×108 μ+/s, and that for cloud muons is 107μ−/s. The beamline consists of the normal‐conducting capture solenoid, the superconducting curved transport solenoid and axial focusing solenoid. The construction of the capture solenoid has been completed and installed in March 2009, and the transport solenoid is now fabricated, and will be installed in the summer of 2011. The calculation of the beamline optics of the axial focusing solenoid is underway.
162176254
Development on Electromagnetic Calorimeter for COMET / PRISM
18393881
Intense Muon Physics Working Group Summary
The intense muon beams which will be available at a neutrino factory provide a unique opportunity for searching for physics beyond the standard model, both in lepton flavor violation and in the search for a permanent electric dipole moment for the muon. Other experiments which can use intense muon beams will also be possible.
122497415
R&D on Proton Extinction Monitor for COMET Project
The COMET experiment searches for a muon to electron conversion process that is one of the lepton flavor violation processes. We use an 8‐GeV pulsed proton beam. The proton extinction ratio is an important parameter. In order to measure this ratio pulse‐by‐pulse, we are developing a monitoring device. This device is called Proton Extinction Monitor and is a gas Cerenkov detector with gating photomultiplier tubes(PMT). The result of the investigation is that ethane is a promising gas for the Cerenkov radiator gas. A gating PMT is under development. We fabricated a divider circuit which switches at 10‐kHz and has a cutoff ratio of 10−6.
121688519
Symmetries and the mass ratio of the electron and muon
A model of symmetries and gauge interactions relating the electron and muon is considered. The model is based on the UL(1)⊗UR(1)⊗RL⊗RR group where UL(1)⊗UR(1) denotes the chiral e-μ rotation and RL⊗RR the chiral reflection of the electron field. The invariance under this group is spontaneously broken by the vacuum expectation values of scalar fields. A zeroth-order vacuum is found for which the zeroth-order electron mass vanishes, while one-loop corrections lead to a finite memμ ratio. The decay process μ → e + γ is strictly forbidden in this model.
119500971
Possible existence of new medium interactions and 3.1- and 3.7-GeV particles
126008905
An Asymmetric collider with the TRISTAN Main Ring