A Two-Mode Time-of-Flight Neutron Reflectometer for a Compact Neutron Source DARIA

Abstract

The concept of a two-mode neutron reflectometer with a polarizer, two spin-flippers and an analyzer of polarization after passing through the sample is presented. A reflectometer designed for a compact neutron source DARIA is planned to measure the spectrum of a reflected “white” neutron beam using the time-of-flight method at a fixed glancing angle with the possibility of using both polarized and non-polarized neutrons. The main geometric and physical parameters of the neutron reflectometer are presented. With a neutron pulse duration τ = 100 µs and a total length of the time-of-flight base L = 8 m, the pulse repetition rate can reach f = 165 Hz for the wavelength range Δλ = 3 Å and resolution Δλ ≅ 0.05 Å. The use of polarization analysis elements of a reflectometer at a beam polarization exceeding 96% and an efficiency of spin flippers close to unity makes it possible to study magnetic thin-film nanostructures in detail.