Alan Bross

MUCOOL/MICE RF Cavity R&D Programs

We report recent progress on normal conducting RF cavity R&D for the US MUCOOL program and international Muon Ionization Cooling Experiment (MICE).

Muon Collider Task Force Report

Muon Colliders offer a possible long term path to lepton-lepton collisions at center-of-mass energies {radical}s {ge} 1 TeV. In October 2006 the Muon Collider Task Force (MCTF) proposed a program of advanced accelerator R&D aimed at developing the Muon Collider concept. The proposed R&D program was motivated by progress on Muon Collider design in general, and in particular, by new ideas that have emerged on muon cooling channel design. The scope of the proposed MCTF R&D program includes muon collider design studies, helical cooling channel design and simulation, high temperature superconducting solenoid studies, an experimental program using beams to test cooling channel RF cavities and a 6D cooling demonstration channel. The first year of MCTF activities are summarized in this report together with a brief description of the anticipated FY08 R&D activities. In its first year the MCTF has made progress on (1) Muon Collider ring studies, (2) 6D cooling channel design and simulation studies with an emphasis on the HCC scheme, (3) beam preparations for the first HPRF cavity beam test, (4) preparations for an HCC four-coil test, (5) further development of the MANX experiment ideas and studies of the muon beam possibilities at Fermilab, (6) studies of howmorexa0» to integrate RF into an HCC in preparation for a component development program, and (7) HTS conductor and magnet studies to prepare for an evaluation of the prospects for of an HTS high-field solenoid build for a muon cooling channel.«xa0less

Status of the nuSTORM Facility and a Possible Extension for Long-Baseline

Neutrino beams produced from the decay of muons in a racetrack-like decay ring (the so called Neutrino Factory) provide a powerful way to study neutrino oscillation physics and, in addition, provide unique beams for neutrino interaction studies. The Neutrinos from STORed Muons (nuSTORM) facility uses a neutrino factory-like design. Due to the particular nature of nuSTORM, it can also provide an intense, very pure, muon neutrino beam from pion decay. This so-called “Neo-conventional muon neutrino beam from nuSTORM makes nuSTORM a hybrid neutrino factory. In this paper we describe the facility and give a detailed description of the neutrino beam fluxes that are available and the precision to which these fluxes can be determined. We then present sensitivity plots that indicated how well the facility can perform for short-baseline oscillation searches and show its potential for a neutrino interaction physics program. Finally, we comment on the performance potential of the Neo-conventional muon neutrino beam optimized for long- baseline neutrino-oscillation physics.

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The stochastic injection scenario used by nuSTORM features the pion decay and secondary muon acceptance in the storage ring’s long decay straight [1,2]. The designed momentum acceptance of the nuSTORM decay ring is centered at 3.8 GeV/c, based on neutrino detector performance, with a

Oscillation Experiments

pm,

Determining the Pion Reference Momentum for nuSTORM Injection Design

10% bin. In order to design the injection section, and to obtain as many useful muons from pion decay as possible, the center momentum of the pion beam being injected needs to be carefully chosen. This paper describes in detail the determination of the center momentum of the pion beam, with simulation from G4Beamline [3].

DESIGN OF THE BEAM COMBINATION SECTION FOR STOCHASTIC INJECTION

The stochastic injection scenario proposed by D. Neuffer in early 1980’s [1] features the injection and acceptance of pions into the muon storage ring, and is used in the design and simulation of nuSTORM injection and ring [2,3]. The pions decay to muons in the long decay straight section of the ring, then the secondary muons are accepted by the straight FODO structure. The critical design element in this scenario is the Beam Combination Section (BCS), which serially includes a defocusing quadrupole, a bending dipole, and a focusing quadrupole. This paper describes in detail the the design of such a BCS and the matching from this BCS to the downstream side of magnetic horn used to collect the pions after target.

Study of low-energy neutrino factory at the Fermilab to DUSEL baseline

This note constitutes a Letter of Interest to study the physics capabilities of, and to develop an implementation plan for, a neutrino physics program based on a Low-Energy Neutrino Factory at Fermilab providing a {nu} beam to a detector at the Deep Underground Science and Engineering Laboratory. It has been over ten years since the discovery of neutrino oscillations [1] established the existence of neutrino masses and leptonic mixing. Neutrino oscillations thus provide the first evidence of particle physics beyond the Standard Model. Most of the present neutrino oscillation data are well described by the 3{nu} mixing model. While a number of the parameters in this model have already been measured, there are several key parameters that are still unknown, namely, the absolute neutrino mass scale, the precise value of the mixing angles, the CP phase {delta} and hence the presence or absence of observable CP-violation in the neutrino sector. Future measurements of these parameters are crucial to advance our understanding of the origin of neutrino masses and of the nature of flavor in the lepton sector. The ultimate goal of a program to study neutrino oscillations goes beyond a first measurement of parameters, and includes a systematic search formorexa0» clues about the underlying physics responsible for the tiny neutrino masses, and, hopefully, the origin of the observed flavor structure in the Standard Model, as well as the possible source of the observed matter-antimatter asymmetry in the Universe. To achieve this goal will almost certainly require precision measurements that go well beyond the presently foreseen program. One of the most promising experimental approaches to achieve some of the goals mentioned above is to build a Neutrino Factory and its corresponding detector. The Neutrino Factory produces neutrino beams from muons which have been accelerated to an energy of, for example, 25 GeV. The muons are stored in a race-track shaped decay ring and then decay along the straight sections of the ring. Since the decay of the muon is well understood, the systematic uncertainties associated with a neutrino beam produced in this manner are very small. Beam diagnostics in the decay ring and a specially designed near detector further reduce the systematic uncertainties of the neutrino beam produced at the Neutrino Factory. In addition since the muon (anti-muon) decays produce both muon and anti-electron neutrinos (anti-muon and electron neutrinos), many oscillation channels are accessible from a Neutrino Factory, further extending the reach in the oscillation parameter space. Over the last decade there have been a number of studies [2-5] that have explored the discovery reach of Neutrino Factories in the small mixing angle, {theta}{sub 13}, and its capability to determine the mass hierarchy and determine if CP is violated in leptons through observation of phase parameter, {delta}. The most recent study to be completed [6], the International scoping study of a future Neutrino Factory and super-beam facility (the ISS), studied the physics capabilities of various future neutrino facilities: super-beam, {beta}-Beam and Neutrino Factory and has determined that the Neutrino Factory with an energy of {approx}25 GeV has the best discovery reach for small values of sin{sup 2}2{theta}{sub 13}, reaching an ultimate sensitivity of between 10{sup -5} and 10{sup -4}. However, for larger values of sin{sup 2}2{theta}{sub 13} (> 10{sup -3}), the sensitivity of other experimental approaches is competitive to that of the 25 GeV Neutrino Factory. The wide-band neutrino beam (WBB) produced at Fermilab and directed towards DUSEL [7] is one such competitor. For the case where sin{sup 2}2{theta}{sub 13} (> 10{sup -3}) is large, initial studies have shown that a Low-Energy Neutrino Factory [8-10] with an energy of, for example, 4 GeV, may be both cost-effective and offers exquisite sensitivity. The required baseline for a Low-Energy Neutrino Factory matches Fermilab to DUSEL and, therefore, its physics potential and implementation should be studied in the context of DUSEL along with those for the WBB.«xa0less

The Muon Cooling RF R&D Program

Cooling muon beams in flight requires absorbers to reduce the muon momentum, accelerating fields to replace the lost momentum in the longitudinal direction, and static solenoidal magnetic fields to focus the muon beams. The process is most efficient if both the magnetic fields and accelerating fields are high and the rf frequency is low. We have conducted tests to determine the operating envelope of high‐gradient accelerating cavities in strong static magnetic fields. These studies have already produced useful information on dark currents, magnetic fields and breakdown in cavities. In addition to continuing our program at 805 MHz, we are starting to test a 201 MHz cavity and are planning to look at a variety of appropriate geometries and materials. In parallel with these activities, we are supporting R&D on models and surface structure.