We have experimentally demonstrated the first non-intrusive 1-GeV proton beam extraction for the generation of muons with a temporal structure optimized for Muon Spin Relaxation/Rotation/Resonance (MuSR) applications. The proton pulses are extracted based on the laser neutralization of 1 GeV hydrogen ion (H-) beam in the high energy beam transport of the Spallation Neutron Source (SNS) accelerator. The maximum flux of the extracted proton beam accounts for only 0.2% of the total proton beam used for neutron production, a marked difference from the 20% reduction at other co-located muon and neutron facilities, and thus the proposed method will result in negligible impact on the SNS operation. This paper describes the development of a fiber/solid-state hybrid laser system that has high flexibility of pulse structure and output power, initial experiments on laser neutralization of H- beam and separation of H0 beam from the existing SNS accelerator beam line, conversion of H0 to proton at the SNS linac dump, and measurement results of 30 ns/50 kHz proton pulses. This system conclusively demonstrates the feasibility of laser-based proton beam extraction to power a world-leading MuSR facility at the SNS.
We discuss the technical feasibility, key machine parameters and major challenges of a 14 TeV c.m.e. muon-muon collider in the LHC tunnel. The luminosity of the collider is evaluated for three alternative muon sources - the PS synchrotron, one of a type developed by the US Muon Accelerator Program (MAP) and a low-emittance option based on resonant muon pair production. Project affordability is also discussed.
We have investigated the feasibility of using compound materials as target for muon production by virtue of simulations using a GEANT4 toolkit. A graphite and two thermostable compound materials, beryllium oxide (BeO) and boron carbide (B4C) were considered as muon production targets and their muon production rates for 600-MeV proton beam were calculated and compared. For thermal analysis, total heat deposited on the targets by the proton beams and the secondary particles was calculated with a MCNPX code, and then the temperature distribution of target was derived from the calculated heat by u…
Ionization cooling is the preferred method for producing bright muon beams. This cooling technique requires the operation of normal conducting, radio-frequency (RF) accelerating cavities within the multi-tesla fields of DC solenoid magnets. Under these conditions, cavities exhibit increased susceptibility to RF breakdown, which can damage channel components and imposes limits on channel length and transmission efficiency. We present a solution to the problem of breakdown in strong magnetic fields. We report, for the first time, stable high-vacuum, copper cavity operation at gradients above 50 …
Feasibility demonstration of a high-momentum, high-purity muon beamline at the J-PARC Hadron Experimental Facility
Research Center for Nuclear Physics (RCNP), The University of Osaka（大阪大学核物理研究中心）；Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)（高能加速器研究机构粒子与核研究研究所）；Institute of Physics, Academia Sinica（中央研究院物理学研究所）；Department of Physics, Graduate school of Science, Kyoto University（京都大学理学研究科物理学系）；Department of Physics, Graduate School of Science, The University of Osaka（大阪大学理学研究科物理学系）；Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate school of Science, Kyoto University（京都大学理学研究科科学冒险与协同研究推进中心）
A focal point for the HEMC'99 workshop was the evaluation of straw-man parameter sets for the acceleration and collider rings of muon colliders at center of mass energies of 10 TeV and 100 TeV. These self-consistent parameter sets are presented and discussed. The methods and assumptions used in their generation are described and motivations are given for the specific choices of parameter values. The assessment of the parameter sets during the workshop is then reviewed and the implications for the feasibility of many-TeV muon colliders are evaluated. Finally, a preview is given of plans for ite…
Besides continued work on the parameters of a 3-4 and 0.5 TeV CoM collider, many studies are now concentrating on a machine near 100 GeV that could be a factory for the s-channel production of Higgs particles. We mention the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay channel, muon cooling, acceleration, storage in a ring and the collider detector. We also mention theoretical and experimental R&D plans for the next several years that should lead…
The international Muon Ionization Cooling Experiment (MICE) is being built, at the Rutherford Appleton Laboratory (RAL), to demonstrate the feasibility of ionization cooling of muon beams. This is one of the major technological steps needed in the development of a muon collider and a neutrino factory based on muon decays in a storage ring. MICE will use particle detectors to measure the cooling effect with high precision, achieving a precision on the measurement of emittance of 0.1% or better. The particle i.d. detectors and trackers must work in harsh environmental conditions due to high magn…
Development of energy-efficient fast cycling accelerator magnets is critical for the next generation of proton rapid cycling synchrotrons (RCS) for neutrino research and booster accelerators of future muon colliders. We see a unique opportunity for having such magnets to be built on base of High Temperature Superconductors (HTS). Besides being superconducting at relatively high temperatures, rare-earth HTS tapes have shown very small AC losses compared to low-temperature NbTi superconductor cables. Recent tests of the HTS-based 0.5 m long two-bore superconducting accelerator magnet have shown …
Over the last decade there has been significant progress in developing the concepts and technologies needed to produce, capture, accelerate and collide high intensity beams of muons. At present, a high-luminosity multi-TeV muon collider presents a viable option for the next generation lepton-lepton collider, which is believed to be needed to fully explore high energy physics in the era following the LHC discoveries. This article briefly reviews the status of the accelerator R&D, addresses the question of the feasibility of a Muon Collider, what needs to be done to prove it and presents project…
The Muon Accelerator Program (MAP) has completed a four-year study on the feasibility of muon colliders and on using stored muon beams for neutrinos. That study was broadly successful in its goals, establishing the feasibility of heavy lepton colliders (HLCs) from the 125 GeV Higgs Factory to more than 10 TeV, as well as exploring using a μ storage ring (MSR) for neutrinos, and establishing that MSRs could provide factory-level intensities of $ν_e (\barν_e)$ and $\barν_μ$ $(ν_μ)$ beams. The key components of the collider and neutrino factory systems were identified. Feasible designs and detail…
Experimental and theoretical activities are underway at CERN with the aim of examining the feasibility of a very-high-flux neutrino source. In the present scheme, a high-power proton beam (some 4 MW) bombards a target where pions are produced. The pions are collected and decay to muons under controlled optical condition. The muons are cooled and accelerated to a final energy of 50 GeV before being injected into a decay ring where they decay under well-defined conditions of energy and emittance. We present the most challenging parts of the whole scenario, the muon capture, the ionisation-coolin…
This paper investigates the feasibility of re-purposing the MuCool Test Area (MTA) beamline and experimental hall to support a Muon Spin Resonance (MuSR) facility, which would make it the only such facility in the US. This report reviews the basic muon production concepts studied and operationally implemented at TRIUMF, PSI, and RAL and their application in the context of the MTA facility. Two scenarios were determined feasible. One, an initial minimal-shielding and capital-cost investment stage with a single secondary muon beamline that utilizes an existing high-intensity beam absorber and, a…
The international Muon Ionization Cooling Experiment (MICE), which is under construction at the Rutherford Appleton Laboratory (RAL), will demonstrate the principle of ionization cooling as a technique for the reduction of the phase-space volume occupied by a muon beam. Ionization cooling channels are required for the Neutrino Factory and the Muon Collider. MICE will evaluate in detail the performance of a single lattice cell of the Feasibility Study 2 cooling channel. The MICE Muon Beam has been constructed at the ISIS synchrotron at RAL, and in MICE Step I, it has been characterized using th…
A Neutrino Factory, sending $>10^{20}$ decay neutrinos per year from a high-energy stored muon beam towards remote detectors, has been suggested as the ultimate tool for precision measurement of the neutrino mixing matrix. Following two rounds of design studies that focused primarily on feasibility, the latest such study has begun the process of cost optimization. New ideas include muon `phase rotation' using high-frequency rf cavities and rapid muon acceleration in non-scaling FFAG rings. The world-wide Neutrino Factory R&D effort is aimed at demonstrating the feasibility of the required tech…
The Muon Ionization Cooling Experiment (MICE) will demonstrate the feasibility of ionization cooling, the technique by which it is proposed to cool the muon beam at a future neutrino factory or muon collider. The position and momentum reconstruction of individual muons in the MICE trackers allows for the development of alternative figures of merit in addition to beam emittance. Contraction of the phase space volume occupied by a fraction of the sample, or equivalently the increase in phase space density at its core, is an unequivocal cooling signature. Single-particle amplitude and non-paramet…
The $μ$E4-LEM beamline at Paul Scherrer Institute (PSI, Switzerland) is a special muon beamline combining the hyprid type surface muon beamline $μ$E4 with the low energy muon facility (LEM) and delivers $μ^{+}$ with tunable energy up to 30 keV for low-energy muon spin rotation experiments (LE-$μ$SR). We investigate a possible upgrade scenario for the surface muon beamline $μ$E4 by replacing the last set of quadrupole triplet with a special solenoid to obtain 1.4 times original beam intensity on the LEM muon moderator target. In order to avoid the muon beam intensity loss at the LEM spectromete…
We are exploring the feasibility of a neutrino factory based on a muon storage ring. In this, beams of nu_mu and nubar_e arise from the decay of mu- particles (or alternatively, nubar_mu and nu_e from mu+). The muons come from the decay of low-energy pions produced by a megawatt proton beam incident on a nuclear target. The muons are captured into a magnetic channel, "cooled" by ionization in liquid hydrogen, accelerated to energy of order 50 GeV, and injected into a storage ring. A nonhorizontal ring can deliver neutrino beams to an on-site detector, as well as to two off-site detectors separ…
The Muon Ionization Cooling Experiment (MICE) collaboration seeks to demonstrate the feasibility of ionization cooling, the technique by which it is proposed to cool the muon beam at a future neutrino factory or muon collider. The emittance is measured from an ensemble of muons assembled from those that pass through the experiment. A pure muon ensemble is selected using a particle-identification system that can reject efficiently both pions and electrons. The position and momentum of each muon are measured using a high-precision scintillating-fibre tracker in a 4\,T solenoidal magnetic field. …
Since 1960's, particle colliders have been in the forefront of particle physics, 29 total have been built and operated, 7 are in operation now. At present the near term US, European and international strategies of the particle physics community are centered on full exploitation of the physics potential of the Large Hadron Collider (LHC) through its high-luminosity upgrade (HL-LHC). The future of the world-wide HEP community critically depends on the feasibility of possible post-LHC colliders. The concept of the feasibility is complex and includes at least three factors: feasibility of energy, …
A portion of the remnant Tevatron program infrastructure at Fermilab is being reconfigured to be used for the generation and delivery of proton and muon beams for new high-precision particle physics experiments. With the 8 GeV Booster as its primary source, the Mu2e experiment will receive 8.9 GeV/c bunched beam on target, after being stored and slow spilled from the Delivery Ring (DR) -- a refurbished debuncher ring from Tevatron antiproton production. For the Muon g-2 experiment, the DR will be tuned for 3.1 GeV/c to capture muons off of a target before sending them to this experiment's Stor…
There have been active efforts in the U.S., Europe, and Japan on the design of a Neutrino Factory. This type of facility produces intense beams of neutrinos from the decay of muons in a high energy storage ring. In the U.S., a second detailed Feasibility Study (FS2) for a Neutrino Factory was completed in 2001. Since that report was published, new ideas in bunching, cooling and acceleration of muon beams have been developed. We have incorporated these ideas into a new facility design, which we designate as Study 2B (ST2B), that should lead to significant cost savings over the FS2 design.
The High Intensity Proton Accelerator (HIPA) cyclotron at the Paul Scherrer Institut (PSI) delivers 590 MeV CW proton beam with a maximum power of 1.42 MW. After extraction, the beam is transferred in a 120 m long channel towards two target stations (TgM and TgE) for surface muon production before depositing its remaining power at the spallation target SINQ for neutron production. As part of the High Intensity Muon Beamline (HIMB) feasibility study, the first of these targets will be replaced with a thicker one thereby increasing the rate of surface muon production. However, a key challenge fo…
In this White Paper for the Snowmass 2021 Process, we propose the establishment of a magnet Leading-Edge technology And Feasibility-directed Program (LEAF Program) to achieve readiness for a future collider decision on the timescale of the next decade. The LEAF Program would rely on, and be synergetic with, generic R&D efforts presently covered - in the US - by the Magnet Development Program (MDP), the Conductor Procurement and R&D (CPRD) Program and other activities in the Office of HEP supported by Early Career Awards (ECA) or Lab Directed R&D (LDRD) funds. Where possible, ties to synergetic…
Stored-muon-beam neutrino factories have been recognized as the best option to measure precisely the elements of the MNSP matrix and sensitively test the consistency of the three-neutrino mixing picture. Now that all three mixing angles have been shown to be nonzero, the motivation for neutrino factory construction is strong. A small number of feasibility issues remain open and are the subject of ongoing R&D. Progress on these R&D efforts is described.
A Neutrino Factory requires an intense and well-cooled (in transverse phase space) muon beam. We discuss a hybrid approach for a linear 4D cooling channel consisting of high-pressure gas-filled RF cavities- potentially allowing high gradients without breakdown- and discrete LiH absorbers to provide the necessary energy loss that results in the required muon beam cooling. We report simulations of the channel performance and its comparison with the vacuum case; we also briefly discuss technical and safety issues associated with cavities filled with high-pressure hydrogen gas. Even with additiona…
