Estimation and measurement of l/d on a cold and thermal neutron guide

Abstract The divergence of a beam for neutron radiography limits the achievable resolution. On a flight tube with collimator, the divergence is given solely by the geometry of the setup. If a neutron guide is used, the divergence depends on the neutron wavelength, and one needs to determine an "effective" divergence for the given spectrum.This paper describes an attempt to estimate this effective divergence and a measurement of the divergence according to the method described by Kobayashi and Wakao.