Speaker
Description
Neutron particle-tracing simulations with the MCUCN code provide valuable insights into the expected ultracold neutron (UCN) performance of the n2EDM experiment at PSI, an input that also determines the statistical sensitivity. They also give reference estimates for further improvements to the UCN optics elements of the apparatus. One important aspect is the definition of the roughness profiles of the surfaces which are encountered by the neutrons. The choice of the roughness model will affect the characteristic time distributions, e.g., the emptying curves of the detected UCNs, or the autocorrelation times of the particle trajectories in the precession chambers. The latter are essential for estimating the transversal depolarization time constant, $T_2$ . We will present recent results from a comparison of several models of surface roughness, including variants of Lambertian and microfacet-based reflection models implemented in the MCUCN code.