Neutron spin-echo integral transform spectroscopy

Abstract

The matrix analysis of neutron spin-echo is extended to the general case of an asymmetric spectrometer configuration. It is shown that an integral transform of the incident or scattered beam spectrum may be measured by scanning the asymmetry, defined as the difference between the number of precessions in the two arms. The problem of inverting the integral transform is considered, and we show how the fast Fourier transform technique may be used as the basis for an efficient numerical solution. Experimental results confirming the calculation are presented. Since only a few precessions of asymmetry are needed to measure the spectrum of a broad incident beam, the technique provides a simple means of spectral analysis suitable for use on medium flux reactors.