Neutrino Factory Research Articles

MICE and nuSTORM

A Neutrino Factory (NF) could deliver precision measurements of the CP-violating phase, δCP, to rival measurements in the quark sector. Current NF designs require muon beam cooling, which the Muon Ionisation Cooling Experiment (MICE) will demonstrate. A lower energy approach to the NF concept, using neutrinos from stored muons (nuSTORM), does not require muon cooling and can contribute significantly to neutrino physics, specifically in the area of cross-section measurements and sterile neutrino searches.

High intensity muon beam source for neutrino beam experiments

High intensity muon beams are essential for Muon accelerators like Neutrino Factories and Muon Colliders. In this study we report on a global optimization of the muon beam production and capture based on end-to-end simulations of the Muon Front End. The study includes the pion beam production target geometry, capture field profile, and forming muon beam into microbunches for further acceleration. The interplay between the transverse and longitudinal beam dynamics during the capture and transport of muon beam is evaluated and discussed. The goal of the optimization is to provide a set of design parameters that delivers high intensity muon beam that could be fit within the acceptance of a muon beam accelerator.

The discovery reach of CP violation in neutrino oscillation with non-standard interaction effects

We have studied the CP violation discovery reach in a neutrino oscillation experiment with superbeam, neutrino factory and monoenergetic neutrino beam from the electron capture process. For NSI satisfying model-dependent bound for shorter baselines (like CERN-Fréjus set-up) there is insignificant effect of NSI on the the discovery reach of CP violation due to δ. Particularly, for the superbeam and neutrino factory we have also considered relatively longer baselines for which there could be significant NSI effects on CP violation discovery reach for higher allowed values of NSI. For the monoenergetic beam only shorter baselines are considered to study CP violation with different nuclei as neutrino sources. Interestingly for non-standard interactions— and of neutrinos with matter during propagation in longer baselines in the superbeam, there is the possibility of better discovery reach of CP violation than that with only Standard Model interactions of neutrinos with matter. For complex NSI we have shown the CP violation discovery reach in the plane of Dirac phase δ and NSI phase . The CP violation due to some values of δ remain unobservable with present and near future experimental facilities in the superbeam and neutrino factory. However, in the presence of some ranges of off-diagonal NSI phase values there are some possibilities of discovering total CP violation for any value even at confidence level for neutrino factory. Our analysis indicates that for some values of NSI phases total CP violation may not be at all observable for any values of δ. Combination of shorter and longer baselines could indicate in some cases the presence of NSI. However, in general for NSIs the CP violation discovery reach is better in neutrino factory set-ups. Using a neutrino beam from the electron capture process for nuclei Sn and 152Yb, we have shown the discovery reach of CP violation in a neutrino oscillation experiment. Particularly for Sn nuclei CP violation could be found for about 51% of the possible δ values for a baseline of 130 km with boost factor . Although the nuclei 152Yb is technically more feasible for the production of a mono-energetic beam, it is found to be unsuitable in obtaining good discovery reach of CP violation.

Influence of space-charge fields on the cooling process of muon beams

In this study, obtaining muon beams with high-density in 6D phase-space is essential for realization of muon colliders, neutrino factories based on accelerated muons beams and other experiments involving muons. While several schemes to compress the beam phase-space by means of muon cooling having been proposed, very little is known about the impact of particle-particle interactions in the whole design. In this paper, we examine the influence of space-change fields on the cooling process of muon beams. We show that the cooling efficiency decreases with the degree of intensity, leading to emittance growth and particle loss for beams with large intensities. We further show that the emittance growth is only longitudinal and present a space-charge compensation solution by means of increasing the rf gradient. With the aid of numerical simulations, we obtain a quantitative relationship between the required compensation gradient and bunch charge and compare our results to earlier theoretical findings.

Probing Lorentz invariance violation with neutrino factories

In this article we show the modification of the number of neutrino events () caused by Lorentz invariant violation (LIV), and 10−23, in neutrino oscillations for a neutrino factory at a distance of 7500 km. The momentum of the muons can vary from 10–50 GeV and we consider decays per year. The modifications in the number of events caused by this LIV parameter could be a strong signal of new physics in a future neutrino factory.

Extrinsic and intrinsic CPT asymmetries in neutrino oscillations

We reconsider the extrinsic and possible intrinsic CPT violation in neutrino oscillations, and point out an identity, i.e., AαβCP=AβαCPT+AαβT, among the CP, T, and CPT asymmetries in oscillations. For three-flavor oscillations in matter of constant density, the extrinsic CPT asymmetries AeeCPT, AeμCPT, AμeCPT, and AμμCPT caused by Earth matter effects have been calculated in the plane of different neutrino energies and baseline lengths. It is found that two analytical conditions can be implemented to describe the main structure of the contours of vanishing extrinsic CPT asymmetries. Finally, without assuming intrinsic CPT symmetry in the neutrino sector, we investigate the possibility to constrain the difference of the neutrino CP-violating phase δ and the antineutrino one δ¯ using a low-energy neutrino factory and the super-beam experiment ESSνSB. We find that |δ−δ¯|≲0.35π in the former case and |δ−δ¯|≲0.7π in the latter case can be achieved at the 3σ confidence level if δ=δ¯=π/2 is assumed.

Estimating matter-inducedCPTviolation in long-baseline neutrino experiments

We examine matter-induced $CPT$ violation effects in long-baseline electron neutrino appearance experiments in a low energy neutrino factory setup. Assuming $CPT$ invariance in vacuum, the magnitude of $CPT$ violating asymmetry in matter has been estimated using the exact expressions for the transition probabilities. The dependence of the asymmetry on the oscillation parameters like mixing angles, mass squared differences, as well as on the Dirac $CP$ violating phase has been investigated.

Muon colliders and neutrino factories

Muon colliders and neutrino factories are attractive options for future facilities aimed at achieving the highest lepton-antilepton collision energies and precision measurements of Higgs boson and neutrino mixing matrix parameters. The facility performance and cost depend on how well a beam of muons can be cooled. Recent progress in muon cooling design studies and prototype tests nourishes the hope that such facilities could be built starting in the coming decade. The status of the key technologies and their various demonstration experiments is summarized. Prospects post-P5 are also discussed.

Muon colliders and neutrino factories

Muon colliders and neutrino factories are attractive options for future facilities aimed at achieving the highest lepton-antilepton collision energies and precision measurements of Higgs boson and neutrino mixing matrix parameters. The facility performance and cost depend on how well a beam of muons can be cooled. Recent progress in muon cooling design studies and prototype tests nourishes the hope that such facilities could be built starting in the coming decade. The status of the key technologies and their various demonstration experiments is summarized. Prospects “post-P5” are also discussed.

Fixed-target hadron production experiments

Results from fixed-target hadroproduction experiments (HARP, MIPP, NA49 and NA61/SHINE) as well as their implications for cosmic ray and neutrino physics are reviewed. HARP measurements have been used for predictions of neutrino beams in K2K and MiniBooNE/SciBooNE experiments and are also being used to improve predictions of the muon yields in EAS and of the atmospheric neutrino fluxes as well as to help in the optimization of neutrino factory and super-beam designs. Recent measurements released by the NA61/SHINE experiment are of significant importance for a precise prediction of the J-PARC neutrino beam used for the T2K experiment and for interpretation of EAS data. These hadroproduction experiments provide also a large amount of input for validation and tuning of hadron production models in Monte-Carlo generators.

Leptophobic dark matter at neutrino factories

High-luminosity fixed-target neutrino experiments present a new opportunity to search for light sub-GeV dark matter and associated new forces. We analyze the physics reach of these experiments to light leptophobic dark states coupled to the Standard Model via gauging the $U(1)_B$ baryon current. When the baryonic vector is light, and can decay to dark matter, we find that the MiniBooNE experiment in its current beam-dump configuration can extend sensitivity to the baryonic fine structure constant down to $\alpha_B\sim 10^{-6}$. This is significantly below the existing limits over much of the sub-GeV mass range currently inaccessible to direct detection experiments.

Beam dump problem and neutrino factory based on an [formula omitted] linear collider

After a collision at the main interaction point the beam of an e+e− Linear Collider can be utilized to construct a neutrino factory with exceptional parameters. We also briefly discuss possible applications of some elements of the proposed scheme to standard fixed target experiments and new experiments with νμN interactions.

Muon-decay medium-baseline neutrino beam facility

Neutrino beam with about 300 MeV in energy, high-flux and medium baseline is considered a rational choice for measuring CP violation before the more powerful Neutrino Factory will be built. Following this concept, a unique neutrino beam facility based on muon-decayed neutrinos is proposed. The facility adopts a continuous-wave proton linac of 1.5 GeV and 10 mA as the proton driver, which can deliver an extremely high beam power of 15 MW. Instead of pion-decayed neutrinos, unprecedentedly intense muon-decayed neutrinos are used for better background discrimination. The schematic design for the facility is presented here, including the proton driver, the assembly of a mercury-jet target and capture superconducting solenoids, a pion/muon beam transport line, a long muon decay channel of about 600 m and the detector concept. The physics prospects and the technical challenges are also discussed.

Optimized capture section for a muon accelerator front end

An optimized design of the solenoidal capture system for a high-power neutrino factory leads to an increase of the useful pions, while minimizing the transverse and longitudinal emittances.

The MICE Run Control System

The Muon Ionization Cooling Experiment (MICE) is a demonstration experiment to prove the feasibility of cooling a beam of muons for use in a Neutrino Factory and/or Muon Collider. The MICE cooling channel is a section of a modified Study II cooling channel which will provide a 10% reduction in beam emittance. In order to ensure a reliable measurement, MICE will measure the beam emittance before and after the cooling channel at the level of 1%, or a relative measurement of 0.001. This renders MICE a precision experiment which requires strict controls and monitoring of all experimental parameters in order to control systematic errors. The MICE Controls and Monitoring system is based on EPICS and integrates with the DAQ, Data monitoring systems, and a configuration database. The new MICE Run Control has been developed to ensure proper sequencing of equipment and use of system resources to protect data quality. A description of this system, its implementation, and performance during recent muon beam data collection will be discussed.

State Machine Operation of the MICE Cooling Channel

The Muon Ionization Cooling Experiment (MICE) is a demonstration experiment to prove the feasibility of cooling a beam of muons for use in a Neutrino Factory and/or Muon Collider. The MICE cooling channel is a section of a modified Study II cooling channel which will provide a 10% reduction in beam emittance. In order to ensure a reliable measurement, MICE will measure the beam emittance before and after the cooling channel at the level of 1%, a relative measurement of 0.001. This renders MICE a precision experiment which requires strict controls and monitoring of all experimental parameters in order to control systematic errors. The MICE Controls and Monitoring system is based on EPICS and integrates with the DAQ, Data monitoring systems, and a configuration database. The cooling channel for MICE has between 12 and 18 superconductnig solenoid coils in 3 to 7 magnets, depending on the staged development of the experiment. The magnets are coaxial and in close proximity which requires coordinated operation of the magnets when ramping, responding to quench conditions, and quench recovery. To reliably manage the operation of the magnets, MICE is implementing state machines for each magnet and an over-arching state machine for the magnets integrated in the cooling channel. The state machine transitions and operating parameters are stored/restored to/from the configuration database and coupled with MICE Run Control. Proper implementation of the state machines will not only ensure safe operation of the magnets, but will help ensure reliable data quality. A description of MICE, details of the state machines, and lessons learned from use of the state machines in recent magnet training tests will be discussed.

MICE data handling on the Grid

The international Muon Ionisation Cooling Experiment (MICE) is designed to demonstrate the principle of muon ionisation cooling for the first time, for application to a future Neutrino factory or Muon Collider. The experiment is currently under construction at the ISIS synchrotron at the Rutherford Appleton Laboratory (RAL), UK. In this paper we present a system – the Raw Data Mover, which allows us to store and distribute MICE raw data – and a framework for offline reconstruction and data management. The aim of the Raw Data Mover is to upload raw data files onto a safe tape storage as soon as the data have been written out by the DAQ system and marked as ready to be uploaded. Internal integrity of the files is verified and they are uploaded to the RAL Tier-1 Castor Storage Element (SE) and placed on two tapes for redundancy. We also make another copy at a separate disk-based SE at this stage to make it easier for users to access data quickly. Both copies are check-summed and the replicas are registered with an instance of the LCG File Catalog (LFC). On success a record with basic file properties is added to the MICE Metadata DB. The reconstruction process is triggered by new raw data records filled in by the mover system described above. Off-line reconstruction jobs for new raw files are submitted to RAL Tier-1 and the output is stored on tape. Batch reprocessing is done at multiple MICE enabled Grid sites and output files are shipped to central tape or disk storage at RAL using a custom File Transfer Controller.

The Reconstruction Software for the Muon Ionization Cooling Experiment Trackers

The international Muon Ionisation Cooling Experiment (MICE) is designed to demonstrate the principle of muon ionization cooling, for application to a future Neutrino Factory or Muon Collider. In order to measure the change in emittance, MICE is equipped with a pair of high precision scintillating fibre trackers. The trackers are required to measure a 10% change in emittance to 1% accuracy (giving an overall precision of 0.1%).This paper describes the tracker reconstruction software, as a part of the overall MICE software framework, MAUS. Channel clustering is described, proceeding to the formation of space-points, which are then associated with particle tracks using pattern recognition algorithms. Finally a full custom Kalman track fit is performed, to account for energy loss and multiple scattering. Exemplar results are shown for Monte Carlo data.

Determining neutrino mass hierarchy from electron disappearance at a low energy neutrino factory

Recent measurements of large ${\ensuremath{\theta}}_{13}$ by the reactor experiments have opened up the possibility of determining the neutrino mass hierarchy, i.e., the sign of the mass squared splitting $\mathrm{\ensuremath{\Delta}}{m}_{31}^{2}$, the $CP$-violating phase ${\ensuremath{\delta}}_{CP}$, and the octant of ${\ensuremath{\theta}}_{23}$. In light of this result, we study the performance of a low energy neutrino factory (LENF) for determination of the mass hierarchy. In particular, we explore the potential of the ${\ensuremath{\nu}}_{e}$ and ${\overline{\ensuremath{\nu}}}_{e}$ disappearance channels at LENF to determine the neutrino mass hierarchy, that is free from the uncertainties arising from the unknown ${\ensuremath{\delta}}_{CP}$ phase and the ${\ensuremath{\theta}}_{23}$ octant. We find that using these electron neutrino (antineutrino) disappearance channels with a standard LENF, it is possible to exclude the wrong hierarchy at $5\ensuremath{\sigma}$ with only 2 years of running, with a muon beam energy above $\ensuremath{\sim}3.5(5.0--10.0)\text{ }\text{ }\mathrm{GeV}$ and baseline longer than $\ensuremath{\sim}1400(1900--2400)\text{ }\text{ }\mathrm{km}$ for an optimistic (conservative) systematic error of 2% (5%).

Testing atmospheric mixing sum rules at precision neutrino facilities

We study the prospects for testing classes of atmospheric mixing sum rules at precision neutrino facilities. Such sum rules, which correlate the atmospheric mixing angle theta23 with the recently measured reactor angle theta13 and the cosine of the oscillation phase delta, are predicted by a variety of semi-direct models based on discrete family symmetry, classified in terms of finite von Dyck groups. We perform a detailed simulation of the performance of the next generation of oscillation experiments, including the wide band superbeam and low-energy neutrino factory proposals, and compare their discriminating power for testing atmospheric mixing sum rules.