163156843
LATTICE DESIGN OF LARGE ACCEPTANCE FFAGS FOR THE PRISM PROJECT
On the design on the PRISM-FFAG, dynamics studies and parameters search was performed by using quasirealistic magnetic fields. This method makes quicker and more accurate dynamics studies possible. INTRODUCTION In order to realize a super muon beam that combines high-intensity, low-energy, narrow energy spread and high purity, the PRISM project has been proposed [1]. In this project, a Fixed Field Alternating Gradient (FFAG) ring is used as a phase rotator. A scaling FFAG that consists of radial sector magnets will be adopted. The PRISM-FFAG has to have both of large transverse acceptance and large momentum acceptance to achieve a high intensity muon beam. Furthermore, long straight sections to install RF cavities are required to obtain a high surviving ratio of the muon. Therefore, the PRISM-FFAG requires its magnets to have large aperture and small opening angle. In such magnets, not only non-linear effects but also magnetic fringing field are important to study the beam dynamics of FFAGs. Although 3D tracking using realistic 3D magnetic field maps made with programs such as TOSCA is the best solution to study the dynamics of FFAGs, it takes long time to make such field maps. On the other hand, the synchrotron optics code such as SAD was used to search initial parameters. It is very useful for rough studies and enable rapid studies, but it is very difficult to estimate tune correctly. On a design process of the PRISM-FFAG, quasi-realistic 3D magnetic field maps were used to study the beam dynamics. A method of designing the PRISM-FFAG lattice and beam optics parameters will be described in the following sections. QUASI-REALISTIC 3D MAGNETIC FIELD A quasi-realistic 3D magnetic field is calculated applying spline interpolation to POISSON 2D fields. Let me illustrate a procedure to make the field map by a case of triplet radial sector magnet as shown in Fig.1. The triplet magnet consists of a focusing magnet, two defocusing magnets, and two field clumps. The axis of coordinates is defined as in Fig.1. An x-axis is considered as a θ-axis in this method. This approximation can work only for thin magnets. As the first step, Bz and Bθ are calculated in several x-z cross sections using POISSON. Figure 1 has five cross sections (r1~r5) for example. Current settings of each cross section are decided by a field index (k value). Figure 2 show a model of the magnet used in POISSON for one cross section. Lines of magnetic force are also plotted. Figure 1. Top view of a triplet magnet. Figure 2. A magnet model used in POISSON calculation. Then, using the Maxwell equations, Br can be derived by: Br(r,θ,zi) = dBz dr       (r,θ ,zi ) (zi − zi−1) + Br(r,θ,zi−1) , where zi is the ith position of z. Thus, we have a rough 3D field map. In particular R direction has very large mesh size. In order to make a fine mesh field map, 2D spline interpolations are applied to the rough field map. A 3D quasi-realistic magnetic field map shows good agreement with TOSCA field (see Fig. 3). Only several minutes is required to make a quasi-realistic field map. Proceedings of EPAC 2004, Lucerne, Switzerland
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.
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.
162176254
Development on Electromagnetic Calorimeter for COMET / PRISM
119500971
Possible existence of new medium interactions and 3.1- and 3.7-GeV particles
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.
126008905
An Asymmetric collider with the TRISTAN Main Ring