First demonstration of ionization cooling by the muon ionization cooling experiment

High-brightness muon beams of energy comparable to those produced by state-of-the-art electron, proton and ion accelerators have yet to be realised. Such beams have the potential to carry the search for new phenomena in lepton-antilepton collisions to extremely high energy and also to provide uniquely well-characterised neutrino beams. A muon beam may be created through the decay of pions produced in the interaction of a proton beam with a target. To produce a high-brightness beam from such a source requires that the phase space volume occupied by the muons be reduced (cooled). Ionization cooling is the novel technique by which it is proposed to cool the beam. The Muon Ionization Cooling Experiment collaboration has constructed a section of an ionization cooling cell and used it to provide the first demonstration of ionization cooling. We present these ground-breaking measurements

Multiple Coulomb scattering of muons in lithium hydride

Copyright © 2022 the author(s). Multiple Coulomb scattering (MCS) is a well-known phenomenon occurring when charged particles traverse materials. Measurements of muons traversing low Z materials made in the MuScat experiment showed that theoretical models and simulation codes, such as GEANT4 (v7.0), over-estimated the scattering. The Muon Ionization Cooling Experiment (MICE) measured the cooling of a muon beam traversing a liquid hydrogen or lithium hydride (LiH) energy absorber as part of a programme to develop muon accelerator facilities, such as a neutrino factory or a muon collider. The energy loss and MCS that occur in the absorber material are competing effects that alter the performance of the cooling channel. Therefore measurements of MCS are required in order to validate the simulations used to predict the cooling performance in future accelerator facilities. We report measurements made in the MICE apparatus of MCS using a LiH absorber and muons within the momentum range 160 to 245 MeV=c. The measured RMS scattering width is about 9% smaller than that predicted by the approximate formula proposed by the Particle Data Group, but within the latter’s stated uncertainty. Data at 172, 200 and 240 MeV=c are compared to the GEANT4 (v9.6) default scattering model. These measurements show agreement with this more recent GEANT4 (v9.6) version over the range of incident muon momenta.SCOAP

Performance of the MICE diagnostic system

A preprint version of the article is available online at https://arxiv.org/abs/2106.05813v2. It may not have been certified by peer review.Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams of a neutrino factory and for multi-TeV lepton-antilepton collisions at a muon collider. The international Muon Ionization Cooling Experiment (MICE) has demonstrated the principle of ionization cooling, the technique by which it is proposed to reduce the phase-space volume occupied by the muon beam at such facilities. This paper documents the performance of the detectors used in MICE to measure the muon-beam parameters, and the physical properties of the liquid hydrogen energy absorber during running.The work described here was made possible by grants from the Department of Energy and National Science Foundation (U.S.A.), the Istituto Nazionale di Fisica Nucleare (Italy), the Science and Technology Facilities Council (U.K.), the European Community under the European Commission Framework Programme 7, the Japan Society for the Promotion of Science and the Swiss National Science Foundation, in the framework of the SCOPES programme

Transverse emittance reduction in muon beams by ionization cooling

Data availability The unprocessed and reconstructed data that support the findings of this study are publicly available on the GridPP computing grid53,54. Source data are provided with this paper. Publications using MICE data must contain the following statement: ‘We gratefully acknowledge the MICE collaboration for allowing us access to their data. Third-party results are not endorsed by the MICE collaboration’.Code availability: The MAUS software that was used to reconstruct and analyse the MICE data is available at ref. 55. The analysis presented here used MAUS version 3.3.2.Change history: 30 July 2024A Correction to this paper has been published: https://doi.org/10.1038/s41567-024-02616-8 .A preprint version of the article is available at arXiv:2310.05669v2 [physics.acc-ph], https://arxiv.org/abs/2310.05669 [v2] Fri, 13 Oct 2023 10:40:14 UTC (963 KB). Report number: STFC-P-2023-004. It has not been certified by peer review.Accelerated muon beams have been considered for the next-generation studies of high-energy lepton–antilepton collisions and neutrino oscillations. However, high-brightness muon beams have not yet been produced. The main challenge for muon acceleration and storage stems from the large phase-space volume occupied by the beam, derived from the production mechanism of muons through the decay of pions. The phase-space volume of the muon beam can be decreased through ionization cooling. Here we show that ionization cooling leads to a reduction in the transverse emittance of muon beams that traverse lithium hydride or liquid hydrogen absorbers in the Muon Ionization Cooling Experiment. Our results represent a substantial advance towards the realization of muon-based facilities that could operate at the energy and intensity frontiers.The work described here was made possible by grants from the Science and Technology Facilities Council (UK); the Department of Energy and the National Science Foundation (USA); the Istituto Nazionale di Fisica Nucleare (Italy); the European Union under the European Union’s Framework Programme 7 (AIDA project, grant agreement no. 262025; TIARA project, grant agreement no. 261905; and EuCARD); the Japan Society for the Promotion of Science; the National Research Foundation of Korea (no. NRF2016R1A5A1013277); the Ministry of Education, Science and Technological Development of the Republic of Serbia; the Institute of High Energy Physics/Chinese Academy of Sciences fund for collaboration between the People’s Republic of China and the USA; and the Swiss National Science Foundation in the framework of the SCOPES programme

First particle-by-particle measurement of emittance in the Muon Ionization Cooling Experiment

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. This paper presents the techniques used to reconstruct the phase-space distributions in the upstream tracking detector and reports the first particle-by-particle measurement of the emittance of the MICE Muon Beam as a function of muon-beam momentum