Yasuo Fukui

An R&D program for targetry and capture at a neutrino factory and muon collider source

The need for intense muon beams for muon colliders and for neutrino factories based on muon storage rings leads to a concept of 1-4 MW proton beams incident on a moving target that is inside a 20-T solenoid magnet, with a mercury jet as a preferred example. Novel technical issues for such a system include disruption of the mercury jet by the proton beam and distortion of the jet on entering the solenoid, as well as more conventional issues of materials lifetime and handling of activated materials in an intense radiation environment. As part of the R&D program of the Neutrino Factory and Muon Collider Collaboration, an R&D eort related to

Progress in designing a muon cooling ring with lithium lenses

We discuss particle tracking simulations in a storage ring with lithium lens inserts designed for the six-dimensional phase space cooling of muons by the ionization cooling. The ring design contains one or more lithium lens absorbers for transverse cooling that transmit the beam with very small beta-function values, in addition to liquid- hydrogen wedge-shaped absorbers in dispersive locations for longitudinal cooling. Such a ring could comprise the final component of a cooling system for use in a muon collider. The beam matching between dipole-quadrupole lattices and the lithium lenses is of particular interest.

Muon storage rings for 6D phase-space cooling

We describe several storage ring designs for reducing the 6-dimensional phase space of circulating muon beams. These rings utilize quadrupole and dipole magnets as well as wedge-shaped, liquid-hydrogen, energy-loss absorbers and energy compensating rf cavities. We obtain evaluations of their cooling performance by particle tracking simulation. Such rings are potentially useful for future Neutrino Factories or Muon Colliders as well as for existing facilities in which cooled, intense muon beams could enhance their physics programs.

Phase rotation at the front end of a neutrino factory

The muon collection scheme for a muon-storage-ring-based neutrino factory consists of a target irradiated with a 1 MW proton beam followed by a 30-m decay channel and then a 300-m long induction linac phase rotation. The purpose of the induction-linac section is to reduce the /spl delta/E/E spread of the collected muons to a value which is manageable for the subsequent buncher and cooling sections. We describe in this paper the overall design concept of the phase-rotation system and give key parameters for the induction linacs.

Design of an optical diffraction radiation beam size monitor at SLAC FFTB

We design a single bunch transverse beam size monitor which will be tested to measure the 28.5 GeV electron/positron beam at the SLAC FFTB beam line. The beam size monitor uses the CCD images of the interference pattern of the optical diffraction radiation from two slit edges which are placed close to the beam path. In this method, destruction of the accelerated electron/positron beam bunches due to the beam size monitoring is negligible, which is vital to the operation of the Linear Collider project.

Polarization effects in the front end of the neutrino factory

The authors summarize the methods used for simulation of polarization effects in the front end of a possible neutrino factory. They first discuss the helicity of muons in the pion decay process. They find that, neglecting acceptance considerations, the average helicity asymptotically approaches a magnitude of 0.185 at large pion momenta. Next they describe the methods used for tracking the spin through the complicated electromagnetic field configurations in the front end of the neutrino factory, including rf phase rotation and ionization cooling channels. Various depolarizing effects in matter are then considered, including multiple Coulomb scattering and elastic scattering from atomic electrons. Finally, they include all these effects in a simulation of a 480 m long, double phase rotation front end scenario.

Comparison of 6D ring cooler schemes and dipole cooler for μ+ μ- collider development

We discuss the various schemes to use ring coolers for 6D cooling for mu+mu- colliders. The earliest successful cooler used dipoles and quadrupoles and a high dispersion low beta region. This was also proposed in the form of solenoids. Recently there have been many new ideas. The simplest is to use a simple dipole ring with high-pressure gas absorber or Li hydride. We show the results of simulations and compare with the results for other cooler schemes.

A Muon Cooling Ring with Curved Lithium Lenses

We design a muon cooling ring with curved Lithium lenses for the 6 dimensional muon phase space cooling. The cooling ring can be the final muon phase space cooling ring for a Higgs Factory, a low energy muon collider. Tracking simulation shows promising muon cooling with simplified magneti element models.

A Muon Ring Cooler with Lithium Lenses

We designed a muon cooling ring with straight inserts with Lithium lenses and injection and extraction which can be used for the final transverse muon cooling for a Higgs Factory, a low energy version of a μ+μ− collider. We demonstrated the transverse phase space cooling of muon beam with the normalized transverse emittance at 0.3 mm*rad with a tracking simulation of the cooling ring with hard‐edged magnetic elements. Work is in progress in using realistic magnetic field for the magnetic elements of the cooling ring.

A neutrino-factory muon storage ring to provide beams for multiple detectors around the world

We briefly discuss the physics motivation for a neutrino factory with varying baseline distances of about 1000 to 9000 km. We describe the amount of non planarity of the storage ring required to service three or four detectors at once. A novel bowtie storage ring is described that could in part provide these beams; a preliminary lattice design is given. We give the space angles between the various detector locations and possible sites for neutrino factories. Finally we describe detectors at the Gran Sasso Laboratory and at a new laboratory near Carlsbad, NM to observe the neutrino interactions with wrong sign leptons.