Time-of-Flight Neutron Reflectometer for the DARIA Compact Neutron Source: Monte Carlo Simulation

Two types of polarized neutron reflectometers have been simulated for the compact neutron source DARIA (Dedicated for Academical Research and Industrial Application), depending on the type of target assembly with thermal or cryogenic moderators. Modeling and optimization of reflectometers were carried out using McStas software package by the Monte Carlo method with specified momentum transfer resolution Delta q/q <= 5% for reflection angles greater than the critical angle theta(cr) and a neutron beam horizontal divergence of Delta theta <= 0.1 degrees for theta < theta(cr) and Delta theta <= 0.033 degrees for theta > theta(cr). To reduce losses in neutrons, neutron guides with a supermirror coating have been proposed. A system of choppers makes it possible to create a neutron spectrum of the required width on a sample.