Muon Ionization Cooling Experiment

Muon Ionization Cooling Experiment
Name	Muon Ionization Cooling Experiment
Location	Rutherford Appleton Laboratory
Date	2007–2017
Participants	Rutherford Appleton Laboratory; Rutherford Appleton Laboratory; Imperial College London; STFC; Fermi National Accelerator Laboratory; CERN; University of Oxford; University of California, Los Angeles; Lawrence Berkeley National Laboratory
Outcome	Demonstration of ionization cooling principles

Muon Ionization Cooling Experiment

The Muon Ionization Cooling Experiment was an international collaboration to demonstrate ionization cooling of muon beams for proposed facilities such as a Neutrino Factory and a Muon Collider. Located at the Rutherford Appleton Laboratory near Oxford, the project involved partners from CERN, Fermilab, Imperial College London, University of Oxford, University of California, Los Angeles, Lawrence Berkeley National Laboratory, and other institutions. The experiment tested technologies relevant to accelerator projects advocated by bodies like the European Strategy for Particle Physics and the Particle Physics Project Prioritization Panel.

Introduction

MICE aimed to provide a proof of principle for ionization cooling, a technique proposed to reduce transverse emittance of muon beams for next-generation facilities such as a Neutrino Factory and a Muon Collider. The collaboration brought together accelerator physicists, detector experts, and cryogenics groups from institutions including CERN, Fermilab, Rutherford Appleton Laboratory, Imperial College London, and Lawrence Berkeley National Laboratory. The program interfaced with global initiatives like the International Muon Ionization Cooling Experiment concept and engaged advisory bodies such as the Particle Physics and Astronomy Research Council and the European Organization for Nuclear Research.

Background and Motivation

Ionization cooling was proposed to address beam phase-space challenges identified in studies at facilities such as Fermilab and CERN and in reports produced by panels including the European Strategy Group and the US Particle Physics Community Planning Exercise. Muons originate from decay chains beginning with proton collisions on targets studied at laboratories like CERN and Brookhaven National Laboratory, generating secondary beams that were characterized at test stands in facilities such as Rutherford Appleton Laboratory and ISIS Neutron and Muon Source. The short muon lifetime, noted in measurements related to experiments at TRIUMF and Paul Scherrer Institute, creates stringent demands on rapid cooling techniques relevant to designs proposed in white papers from Fermilab and design studies undertaken at Cornell University and Stanford Linear Accelerator Center.

Experimental Design and Components

MICE used a channel composed of absorbers, radio-frequency cavities, and superconducting solenoids based on engineering from groups at Imperial College London, University of Oxford, Lawrence Berkeley National Laboratory, and Brookhaven National Laboratory. The absorber modules employed liquid hydrogen systems developed with cryogenic expertise from Rutherford Appleton Laboratory and CERN collaborators. RF cavities were designed drawing on technology heritage from SLAC National Accelerator Laboratory and DESY, and superconducting coil design incorporated contributions from Tesla Technology Collaboration-style efforts and ITER cryogenics teams. The mechanical and safety engineering interfaces referenced standards used by UKAEA and STFC.

Beamline and Detector Systems

MICE’s beamline transported muons from an upstream target and collection system modeled on concepts developed at Fermilab and CERN facilities, with momentum selection and particle identification borrowing techniques from beamlines at ISIS Neutron and Muon Source and Paul Scherrer Institute. Particle identification detectors included time-of-flight systems, Cherenkov counters, and calorimetry informed by designs from KEK and DESY test beams. Tracking detectors relied on scintillating-fibre modules and silicon photomultiplier readout developed in collaboration with groups at University of Geneva, University of Manchester, and University of California, Berkeley. Data acquisition and control systems integrated expertise from CERN control frameworks, Fermilab accelerator operations, and software contributions from GridPP and Open Science Grid communities.

Results and Performance

MICE delivered single-particle measurements demonstrating a measurable reduction in transverse emittance consistent with ionization cooling theory developed in analytic work associated with Brookhaven National Laboratory and simulation studies from CERN and Fermilab. The collaboration published results benchmarking cooling performance against predictions from codes originating at Lawrence Berkeley National Laboratory and SLAC National Accelerator Laboratory beam dynamics groups. Key performance metrics were compared to target parameters discussed in reports by the Particle Data Group and accelerator studies conducted at Cornell University and Stanford Linear Accelerator Center, influencing design assumptions for Neutrino Factory and Muon Collider feasibility studies at Fermilab and CERN.

Impact and Future Developments

MICE established technological and experimental foundations adopted by subsequent accelerator R&D programs at Fermilab, CERN, KEK, and national laboratories such as Brookhaven National Laboratory and TRIUMF. The experiment’s outcomes informed conceptual designs in international roadmap documents from the European Strategy for Particle Physics and contributed to proposals submitted to funding agencies including STFC and DOE. Future developments envisaged leverage of MICE-derived technologies in facility designs promoted by consortia involving CERN, Fermilab, Rutherford Appleton Laboratory, Imperial College London, and University of Oxford, and influence studies in high-energy physics initiatives like the Future Circular Collider and advanced acceleration programs at DESY.

Category:Particle physics experiments