Muon Storage Research Articles

Erratum: “Neutrinoless double beta decay” at a neutrino factory [Phys. Rev. D63, 054031 (2001)

We examine the prospects of detecting an analogous process of neutrinoless double beta decay at a neutrino factory from a high energy muon storage ring. Limits from LEP experiments, neutrinoless double beta decay as well as from global fits have to be incorporated and severely restrict the results. We investigate what limits on light and heavy effective Majorana neutrino masses can be obtained and compare them with existing ones. Discussed are also contributions from right-handed neutrinos and purely right-handed interactions. Other ``new physics'' contributions to the same final state might produce large event numbers.

Signals ofR-parity violating supersymmetry in neutrino scattering at muon storage rings

Neutrino oscillation signals at muon storage rings can be faked by supersymmetric (SUSY) interactions in an R-parity violating scenario. We investigate the \ensuremath{\tau}-appearance signals for both long-baseline and near-site experiments, and conclude that the latter is of great use in distinguishing between oscillation and SUSY effects. On the other hand, for a wide and phenomenologically consistent choice of parameters, SUSY can cause a manifold increase in the event rate for wrong-sign muons at a long-baseline setting, thereby providing us with signatures of new physics.

Neutrino oscillation physics at a ν factory

The potential of a neutrino factory based on muon storage rings at determining the neutrino mass matrix is summarized.

Experiments at fermilab after minos

The recent Superkamiokande [1] results for the ν μ deficit in the atmospheric neutrino flux have opened an exciting era in neutrino physics. Fermilab has started to investigate the physics potential of a new generation of neutrino experiments based either on muon storage ring neutrino factories or on conventional neutrino beams which use a “super” intense proton source (superbeams). A summary of the status and results from these studies are presented in this note.

Design and simulation of muon ionization cooling channels for the Fermilab Neutrino Factory feasibility study

In the past few years, the concept of a high intensity muon storage ring has been pursued as an option for the next generation neutrino source. To produce the high intensity muon beam needed for the successful operation of a neutrino source, on the order of 1020 muon decays per year, the phase space occupied by the muon beam must be significantly reduced before the beam is accelerated. The initial transverse emittance of the muon beam before acceleration is assumed to be 9p mm rad. Because of the time limitation imposed by the muon lifetime, the technique employed to accomplish the desired emittance reduction is ionization cooling. In this paper we present two ionization cooling lattice designs, which use solenoidal focusing elements and liquid hydrogen absorbers to reduce the muon beam phase space. We discuss the design concepts and engineering constraints for these lattices and present simulation results obtained using a detailed tracing code with a complete model of muon-matter interactions. The reduction in transverse emittance is approximately a factor of 5. This result is within a factor of 2 of the total cooling requirements for a successful neutrino factory design and within a factor of 1.4 of the requirements for the main cooling section specified in the conceptual design of this machine.

Have We Glimpsed ‘New Physics’ in the Muon’s Anomalous Magnetic Moment?

A g-2 measurement at Brook-haven’s muon storage ring shows a small but tantalizing disagreement with the standard model.

Probing the violation of equivalence principle at a muon storage ring via neutrino oscillation

We examine the possible tests of violation of the gravitational equivalence principle (VEP) at a muon storage ring via neutrino oscillation experiments. If the gravitational interactions of the neutrinos are not diagonal in the flavour basis and the gravitational interaction eigenstates have different couplings to the gravitational field, this leads to the neutrino oscillation. If one starts with μ + beam then appearance of τ ±, e + and μ − in the final state are the signals for neutrino oscillation. We have estimated the number of μ − events in this scenario in ν μ – N deep inelastic scattering. Final state lepton energy distribution can be used to distinguish the VEP scenario from the others. A large area of VEP parameter space can be explored at a future muon storage ring facility with moderate beam energy.

“Neutrinoless double beta decay” at a neutrino factory

We examine the prospects of detecting an analogous process of neutrinoless double beta decay at a neutrino factory from a high energy muon storage ring. Limits from LEP experiments, neutrinoless double beta decay as well as from global fits have to be incorporated and severely restrict the results. We investigate what limits on light and heavy effective Majorana neutrino masses can be obtained and compare them with existing ones. Discussed are also contributions from right-handed neutrinos and purely right-handed interactions. Other ``new physics'' contributions to the same final state might produce large event numbers.

Muon storage rings as neutrino factories

I will present some results of recent studies of neutrino factories from muon storage rings. These facilities are intended to produce high neutrino rates even at long baselines and allow precision studies of the neutrino mixing matrix similar to those being done for the quark mixing matrix.

Neutrino factories: Accelerator facilities

This paper describes the accelerator facilities needed for a neutrino factory. Such facilities consist of several modules: A proton source, a proton target, followed by muon capture, muon cooling, muon acceleration and muon storage. The status of these modules is presented. The conclusions contain a discussion of the status of neutrino factory studies, and a programme for future research and development.

Stability of Muon Beams to Langmuir Waves during Ionization Cooling

Fast cooling of muon beams will be needed for building either TeV muon colliders that might explore the electroweak gauge symmetry breaking or muon storage rings that could become ultrabright neutrino sources. Stochastic and electron cooling take longer than the muon lifetime, so attention has been focused on the potentially faster but less explored ionization cooling. Addressing recent concerns that excitation of Langmuir waves might be deleterious for ionization cooling techniques, we show that, while the hydrodynamic instability indeed might be dangerous, the waves are, in fact, stabilized through a combination of resistive and kinetic effects at a very modest emittance of the beam.

Searches for the appearance of $\nu_\tau$ using neutrino beams from muon storage rings

We study the possibilities offered by muon storage rings for tau-neutrino appearance experiments due to nu_mu to nu_tau and nu_e to nu_tau oscillations. Tau event rates for such experiments are first discussed with a view to examining their variation prior to the inclusion of experimental cuts, in order to better understand how baselines, beam energies, forward peaking of decay neutrinos with increasing energies and average fluxes intercepted by detectors of various sizes can affect their optimization. Subsequently, event rates implementing cuts are computed for hadronic and wrong-sign lepton decay modes and used to plot 90% C.L. contours for the parameters that can be explored in such experiments. The expected scaling of the contours with energy and baseline is discussed. The results show that even for modest muon beam energies, convincing coverage of the Super Kamiokande parameters is possible. In addition, very significant enlargement of present-day bounds on the mass and mixing parameters of all types of neutrino oscillations is guaranteed by such searches.

Electromagnetic calorimeters for the BNL muon ( g−2) experiment

A set of 24 lead/scintillating fiber electromagnetic calorimeters has been constructed for the new muon ( g−2) experiment at the Brookhaven AGS. These calorimeters were designed to provide very good energy resolution for electrons up to 3 GeV while also yielding excellent timing information. Special requirements in the experiment related to the uniformity of response, the short-term gain and timing stability, and the neutron background led to several unusual design features. The calorimeters were tested and calibrated with electrons in the energy range 0.5–4.0 GeV and have been installed and used in the muon storage ring. The design criteria, construction, and performance of the system are described.

Erratum:CPandTviolation in long baseline experiments with low energy neutrinos from a muon storage ring [Phys. Rev. D61, 073012 (2000)

Stimulated by the idea of PRISM, a very high intensity muon ring with rather low energy, we consider possibilities of observing CP-violation effects in neutrino oscillation experiments. More than 10% of CP-violation effect can be seen within the experimentally allowed region. Destructive sum of matter effect and CP-violation effect can be avoided with use of initial nu_e beam. We finally show that the experiment with (a few) x 100 MeV of neutrino energy and (a few) x 100 km of baseline length, which is considered in this paper, is particularly suitable for a search of CP violation in view of statistical error.

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 ${\ensuremath{\nu}}_{e}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ oscillations, measure the corresponding amplitude ${\mathrm{sin}}^{2}2{\ensuremath{\theta}}_{13},$ and determine the sign of the atmospheric-scale $\ensuremath{\delta}{m}_{32}^{2}$ via matter effects. A 50 kt detector, a stored muon energy ${E}_{\ensuremath{\mu}}>~20 \mathrm{GeV}$ and ${10}^{19}$ muon decays would enable these goals to be met provided ${\mathrm{sin}}^{2}2{\ensuremath{\theta}}_{13}>0.01.$ The determination of the sign of $\ensuremath{\delta}{m}_{32}^{2}$ also requires a baseline $L>~2000 \mathrm{km}.$ An upgraded neutrino factory with $\mathrm{O}{(10}^{20})$ decays would enable the first observation of ${\ensuremath{\nu}}_{e}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ oscillations. With $\mathrm{O}{(10}^{21})$ decays the effects of a large $\mathrm{CP}$ 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.

Neutrino physics at the muon collider

The neutrino beams originating from a muon storage ring can be used to study interactions of neutrinos with matter with unpreceding accuracy. Future high-statistics and high-precision measurements of neutrino interactions can improve our current knowledge of electroweak and strong interactions. For example, new experiments could determine the CKM matrix element V cd to a precision comparable to that of V us and the electroweak mixing angle to a precision equivalent to that of the W mass. Neutrino scattering from polarised targets would be within reach.

RF capture variations for the muon storage ring neutrino source

We present possible scenarios for capturing the long bunches of a muon source into a string of high-frequency bunches for cooling and acceleration into a muon storage ring for neutrinos. A matched solution using double-harmonic RF appears appropriate to the Palmer neutrino source scenario (R. Palmer, Muon Collider Note 46, 9/3/99, Proceedings of Lyon Workshop on Neutrino Factories); however, different scenarios (i.e., with single stage RF rotation) may prefer an adiabatic solution to minimize phase-space dilution.

Questions of identity

As an introduction to νFact ’99, the ICFA/ECFA Workshop on Neutrino Factories Based on Muon Storage Rings, I place the issues of neutrino properties and neutrino oscillations in the broader context of fermion flavor.

Design concepts for a muon storage ring neutrino source

We described a preliminary design study for a muon storage ring neutrino source that could be built as a step towards the first muon collider. In our design the neutrino beam is produced by 3×10 20 muon decays per year occurring within the straight section of a muon storage ring, and that intensity could be increased by upgrading the proton source intensity. The resulting neutrino flux is sufficient to produce hundreds of charged current interactions per year in a reasonable sized detector on the other side of the Earth.

Large acceptance 30 GeV muon storage rings for neutrino production: lattice design

Two competing goals control the lattice design of a muon storage ring for a neutrino factory [1]. One goal is achieving large transverse and longitudinal acceptances in order to minimize the degree of muon-beam cooling required. (This condition presumes large-emittance muon beams can be effectively accelerated.) The second is provision of a long insertion in which a significant fraction of the stored muons decay and produce a relatively colinear beam of neutrinos. In this work, a 30 GeV muon storage ring is presented which is optimized for acceptance and maximal neutrino-beam production.