Muon Ionisation Cooling Experiment

The Muon Ionisation Cooling Experiment (MICE) is trying to demonstrate ionisation cooling, that is a reduction in the emittance of a charged particle beam. The emittance is the volume occupied by a beam in position and momentum phase space. During ionisation cooling the charged particle beam is passed through a series of absorbers and radio-frequency (RF) cavities. The absorbers, such as liquid Hydrogen or Lithium Hydride, reduce the overall momentum of the particles, while the RF cavities reaccelerate the particles along the axis of the direction of motion of the beam. This process replenishes the longitudinal momentum of the beam but reduces the transverse momentum. Thus, the emittance of the beam has been reduced.
One of the main motivations behind ionisation cooling is the possibility of future neutrino experiments to analyse neutrino oscillations, neutrino masses and the mass hierarchy and whether the neutrino is a Majorana particle.
To create a muon beam of sufficient intensity for neutrino factory detectors requires a muon beam of sufficient density. However, the muon beam has an incredibly short lifetime (2.2s). The muon beam is created from the decay of a highly dispersed pion beam. The pion beam is highly dispersed as it has been created from the bombardment of a proton beam against a target. Current confinement techniques are not able to create muon beams of sufficient density within the lifetime of the muon; however, ionisation cooling would allow for this.MICE uses a number of detectors to identify the particles travelling in the experiment (pions, muons, electrons) such as Time-of-Flight systems, Cherenkov counters, Kloe Light and an electron Muon Ranger. The effectiveness of the Particle Identification system will be looked at in this project.
MICE also uses two solenoidal spectrometers, each having five scintillating fibre stations which contain the particle beam and track the motion of the particles travelling through it. The results from the various experiments carried out need to be extensively analysed to determine the effectiveness of ionisation cooling and to what accuracy. For example, the emittance
growth due to optical aberrations (e.g spherical, chromatic) in the magnets will be explored during this project.