Measurement of energy loss by muons in Lithium Hydride on MICE

Abstract

The Muon Ionisation Cooling Experiment (MICE) has been commissioned to provide the first demonstration of ionisation cooling. MICE will aim to demonstrate that ionisation cooling can be used to reduce of the emittance of a beam of muons to meet the requirements of future particle physics experiments such as the Neutrino Factory, or Muon Collider. As of October 2016, commissioning of Step IV of MICE has been completed which provides an opportune time to make material physics studies on the absorber material. The cooling formula that MICE will use to measure the emittance reduction was reviewed. It is shown that the energy loss term is important when measuring cooling, and an accurate measurement of the energy loss will hence improve the accuracy of the cooling formula. The physics of ionisation cooling is also reviewed. The primary absorber used in the early data taking of MICE Step IV will be a 65mm disk of Lithium Hydride. The energy loss of Lithium Hydride was estimated using the equations of energy loss developed by Bethe. Methods were developed in this thesis to make measurements of the energy loss using data from the MICE trackers, and the timeof- flight data through the cooling channel. The energy loss of muons in monte-carlo simulations measured with the two alternative methods was found to be in agreement, with a measurement by the trackers of 9.02 ± 0.07, and from simulated time-of-flight of 9.32 ± 0.15. The first measurement of energy loss by 200 MeV/c muons was made using time-of-flight data using real muons in the MICE channel of ∆E = 9.23 ± 0.13 MeV, corresponding to a stopping power of Lithium Hydride of dE/dx = 1.42 ± 0.02 MeV g−1 cm2.