The liquid-hydrogen absorber for MICE

TL;DR

This paper details the design, construction, and performance of a liquid-hydrogen absorber system used in the MICE experiment to demonstrate muon beam cooling via ionization, crucial for future muon accelerators.

Contribution

It introduces the complete liquid-hydrogen absorber system for MICE, including cryogenic, safety, and control systems, and reports on its operational performance.

Findings

Successful cool-down and liquefaction achieved

Stable operation during experiments demonstrated

Effective safety measures implemented

Abstract

The Muon Ionization Cooling Experiment (MICE) has been built at the STFC Rutherford Appleton Laboratory to demonstrate the principle of muon beam phase-space reduction via ionization cooling. Muon beam cooling will be required at a future proton-derived neutrino factory or muon collider. Ionization cooling is achieved by passing the beam through an energy-absorbing material, such as liquid hydrogen, and then re-accelerating the beam using RF cavities. This paper describes the hydrogen system constructed for MICE including: the liquid-hydrogen absorber, its associated cryogenic and gas systems, the control and monitoring system, and the necessary safety engineering. The performance of the system in cool-down, liquefaction, and stable operation is also presented.