S. Geer

Physics at a future Neutrino Factory and super-beam facility

The conclusions of the Physics Working Group of the International Scoping Study of a future Neutrino Factory and super-beam facility (the ISS) are presented. The ISS was carried out by the international community between NuFact05, (the 7th International Workshop on Neutrino Factories and Super-beams, Laboratori Nazionali di Frascati, Rome, 21–26 June 2005) and NuFact06 (Ivine, CA, 24–30 August 2006). The physics case for an extensive experimental programme to understand the properties of the neutrino is presented and the role of high-precision measurements of neutrino oscillations within this programme is discussed in detail. The performance of second-generation super-beam experiments, beta-beam facilities and the Neutrino Factory are evaluated and a quantitative comparison of the discovery potential of the three classes of facility is presented. High-precision studies of the properties of the muon are complementary to the study of neutrino oscillations. The Neutrino Factory has the potential to provide extremely intense muon beams and the physics potential of such beams is discussed in the final section of the report.The conclusions of the Physics Working Group of the International Scoping Study of a future Neutrino Factory and super-beam facility (the ISS) are presented. The ISS was carried out by the international community between NuFact05, (the 7th International Workshop on Neutrino Factories and Superbeams, Laboratori Nazionali di Frascati, Rome, June 21-26, 2005) and NuFact06 (Irvine, California, 2430 August 2006). The physics case for an extensive experimental programme to understand the properties of the neutrino is presented and the role of high-precision measurements of neutrino oscillations within this programme is discussed in detail. The performance of second generation super-beam experiments, beta-beam facilities, and the Neutrino Factory are evaluated and a quantitative comparison of the discovery potential of the three classes of facility is presented. High-precision studies of the properties of the muon are complementary to the study of neutrino oscillations. The Neutrino Factory has the potential to provide extremely intense muon beams and the physics potential of such beams is discussed in the final section of the report. The ISS Physics Working Group Editors: S.F. King1, K. Long2, Y. Nagashima3, B.L. Roberts4, and O. Yasuda5.

Long baseline neutrino physics with a muon storage ring neutrino source

We examine the physics capabilities of known flavor neutrino beams from intense muon sources. We find that long-baseline neutrino experiments based on such beams can provide precise measurements of neutrino oscillation mass and mixing parameters. Furthermore, they can test whether the dominant atmospheric neutrino oscillations are {nu}{sub {mu}}{yields}{nu}{sub {tau}} and/or {nu}{sub {mu}}{yields}{nu}{sub s}, determine the {nu}{sub {mu}}{yields}{nu}{sub e} content of atmospheric neutrino oscillations, and measure {nu}{sub e}{yields}{nu}{sub {tau}} appearance. Depending on the oscillation parameters, they may be able to detect Earth matter and CP violation effects and to determine the ordering of some of the mass eigenstates. (c) 2000 The American Physical Society.

Long baseline study of the leading neutrino oscillation at a neutrino factory

Within the framework of three-flavor neutrino oscillations, we consider the physics potential of {nu}{sub e}{yields}{nu}{sub {mu}} appearance and {nu}{sub {mu}}{yields}{nu}{sub {mu}} survival measurements at a neutrino factory for a leading oscillation scale {delta}m{sup 2}{approx}3.5x10{sup -3} eV{sup 2}. Event rates are evaluated versus baseline and stored muon energy, and optimal values discussed. Over a sizable region of oscillation parameter space, matter effects would enable the sign of {delta}m{sup 2} to be determined from a comparison of {nu}{sub e}{yields}{nu}{sub {mu}} with {nu}(bar sign){sub e}{yields}{nu}(bar sign){sub {mu}} event rates and energy distributions. It is important, therefore, that both positive and negative muons can be stored in the ring. Measurements of the {nu}{sub {mu}}{yields}{nu}{sub {mu}} survival spectrum could determine the magnitude of {delta}m{sup 2} and the leading oscillation amplitude with a precision of O (1%-2%). (c) 2000 The American Physical Society.

NEUTRINO FACTORY AND BETA BEAM EXPERIMENTS AND DEVELOPMENT.

The long-term prospects for fully exploring three-flavor mixing in the neutrino sector depend upon an ongoing and increased investment in the appropriate accelerator R&D. Two new concepts have been proposed that would revolutionize neutrino experiments, namely the Neutrino Factory and the Beta Beam facility. These new facilities would dramatically improve our ability to test the three-flavor mixing framework, measure CP violation in the lepton sector, and perhaps determine the neutrino mass hierarchy, and, if necessary, probe extremely small values of the mixing angle {theta}{sub 13}. The stunning sensitivity that could be achieved with a Neutrino Factory is described, together with our present understanding of the corresponding sensitivity that might be achieved with a Beta Beam facility. In the Beta Beam case, additional study is required to better understand the optimum Beta Beam energy, and the achievable sensitivity. Neither a Neutrino Factory nor a Beta Beam facility could be built without significant R&D. An impressive Neutrino Factory R&D effort has been ongoing in the U.S. and elsewhere over the last few years and significant progress has been made towards optimizing the design, developing and testing the required accelerator components, and significantly reducing the cost. The recent progress is described here.

A Low energy neutrino factory for large theta(13)

If the value of {theta}{sub 13} is within the reach of the upcoming generation of long-baseline experiments, T2K and NOvA, they show that a low-energy neutrino factory, with peak energy in the few GeV range, would provide a sensitive tool to explore CP-violation and the neutrino mass hierarchy. They consider baselines with typical length 1000-1500 km. The unique performance of the low energy neutrino factory is due to the rich neutrino oscillation pattern at energies between 1 and 4 GeV at baselines {Omicron}(1000) km. They perform both a semi-analytical study of the sensitivities and a numerical analysis to explore how well this setup can measure {theta}{sub 13}, CP-violation, and determine the type of mass hierarchy and the {theta}{sub 23} quadrant. A low energy neutrino factory provides a powerful tool to resolve ambiguities and make precise parameter determinations, for both large and fairly small values of the mixing parameter {theta}{sub 13}.

Neutrino oscillations at an entry-level neutrino factory and beyond

We consider the parameters of an entry-level neutrino factory designed to make the first observation of {nu}{sub e}{yields}{nu}{sub {mu}} oscillations, measure the corresponding amplitude sin{sup 2}2{theta}{sub 13}, and determine the sign of the atmospheric-scale {delta}m{sub 32}{sup 2} via matter effects. A 50 kt detector, a stored muon energy E{sub {mu}}{>=}20 GeV and 10{sup 19} muon decays would enable these goals to be met provided sin{sup 2}2{theta}{sub 13}>0.01. The determination of the sign of {delta}m{sub 32}{sup 2} also requires a baseline L{>=}2000 km. An upgraded neutrino factory with O(10{sup 20}) decays would enable the first observation of {nu}{sub e}{yields}{nu}{sub {tau}} oscillations. With O(10{sup 21}) decays the effects of a large CP phase could be measured in the case of the large angle matter oscillation solution to the solar neutrino anomaly. Our analysis includes a family of three-neutrino models that can account for the atmospheric and solar neutrino oscillation indications. (c) 2000 The American Physical Society.

Neutrino factory for both large and small θ 13

An analysis of the neutrino oscillation physics capability of a low energy Neutrino Factory is presented, including a first simulation of the detector efficiency and event energy threshold. The sensitivity of the physics reach to the presence of backgrounds is also studied. We consider a representative baseline of 1480 km, we use muons with 4.12 GeV energy and we exploit a very conservative estimate of the energy resolution of the detector. Our analysis suggests an impressive physics reach for this setup, which can eliminate degenerate solutions, for both large and small values of the mixing angle theta_13, and can determine leptonic CP violation and the neutrino mass hierarchy with extraordinary sensitivity.

Physics at a Fermilab proton driver

Author(s): Albrow, MG; Antusch, S; Babu, KS; Barnes, T; Bazarko, AO; Bernstein, RH; Bowles, TJ; Brice, SJ; Ceccucci, A; Cei, F; KCheung, HW; Christian, DC; Collar, JI; Cooper, J; Cooper, PS; Curioni, A; deGouvea, A; DeJongh, F; Derwent, PF; Diwan, MV; Dobrescu, BA; Feldman, GJ; Finley, DA; Fleming, BT; Geer, S; Greene, GL; Grossman, Y; Harris, DA; Horowitz, CJ; Hertzog, DW; Huber, P; Imazato, J; Jansson, A; Jungmann, KP; Kasper, PA; Kersten, J; Kettell, SH; Kuno, Y; Lindner, M; Mandelkern, M; Marciano, WJ; Melnitchouk, W; Mena, O; Michael, DG; Miller, JP; Mills, GB; Morfin, JG; Nguyen, H | Abstract: This report documents the physics case for building a 2 MW, 8 GeV superconducting linac proton driver at Fermilab.This report documents the physics case for building a 2 MW, 8 GeV superconducting linac proton driver at Fermilab.

Neutral currents and tests of three-neutrino unitarity in long-baseline experiments

We examine a strategy for using neutral current measurements in long-baseline neutrino oscillation experiments to put limits on the existence of more than three light, active neutrinos. We determine the relative contributions of statistics, cross-section uncertainties, event misidentification and other systematic errors to the overall uncertainty of these measurements. As specific case studies, we make simulations of beams and detectors that are like the K2K, T2K and MINOS experiments. We find that the neutral current cross-section uncertainty and contamination of the neutral current signal by charge current events allow a sensitivity for determining the presence of sterile neutinos at the 0.10–0.15 level in probablility.

Short-baseline neutrino oscillations at a neutrino factory

Within the framework of three-neutrino and four-neutrino scenarios that can describe the results of the LSND experiment, we consider the capabilities of short-baseline neutrino oscillation experiments at a neutrino factory. We find that, when short-baseline (L{approx}<100 km) neutrino factory measurements are used together with other accelerator-based oscillation results, the complete three-neutrino parameter space can best be determined by measuring the rate of {nu}{sub e}{yields}{nu}{sub {tau}} oscillations, and measuring CP violation with either {nu}{sub e}{yields}{nu}{sub {mu}} or {nu}{sub {mu}}{yields}{nu}{sub {tau}} oscillations (including the corresponding antineutrino channels). With measurements of CP violation in both {nu}{sub e}{yields}{nu}{sub {mu}} and {nu}{sub {mu}}{yields}{nu}{sub {tau}} it may be possible to distinguish between the three- and four-neutrino cases.