A new Monte-Carlo based simulation for the CryoEDM experiment

This thesis presents a new Monte-Carlo based simulation of the physics of ultra-cold neutrons (UCN) in complex geometries and its application to the CryoEDM experiment. It includes a detailed description of the design and performance of this simulation along with its use in a project to study the magnetic depolarisation time of UCN within the apparatus due to magnetic impurities in the measurement cell, which is a crucial parameter in the sensitivity of a neutron electricdipole-moment (nEDM) experiment. This project involved experimental measurements taken at the Institut Laue Langevin (ILL) of the magnetic environment inside of CryoEDM's measurement cell, along with the magnetic field produced by a set of 19 coils around the cell used to optimise the field in particular locations. It also involved the development of a separate computer program to find the required current setting of these coils so as to minimise the field gradient across the measurement cell, and then use of the simulation to study the effect of these coil configurations on the magnetic depolarisation time.