A dynamically adjustable wavelength-sensitive neutron filter

Abstract

The prototype of a wavelength-sensitive neutron filter has been realized and tested successfully for the first time. The filter exploits the neutron wavelength dependence of the transparency of 3 He gas. The analysis of test results gives high wavelength resolution ∆λ/λ ≃ 0.5% over the broad wavelength range 0.2-5.2Å. We propose an idea to expand the filter range in the short wavelength direction by use of a cryogenic environment, and also consider the use of media using other than 3 He gas. The proposed filter might be used in advanced reflectometers and SANS2D neutron scattering instruments.