Dispersion free measurements in neutron interferometry
Abstract
Neutron interferometry is a method of highaccuracy determination of neutron scattering length b_{c}. The phase shift acquired by a neutron wave that propagates through a sample inserted in one of the beams of an interferometer is proportional to the neutron wavelength. A knowledge of it precisely defines the accuracy of the determination of b_{c}. As a solution of this problem, the nondispersive sample geometry was proposed. In this case the phase shift is λindependent but the very precise orientation of the sample relative to the crystal planes of the interferometer is required. To overcome this obstacle a new nondispersive phase difference method was developed which achieves an accuracy in the determination of b_{c} of even better than 10 ^{4}, i.e. at the level of 10 ^{5}. This method was used for the highaccuracy measurement of the coherent scattering length of Si. Experiments carried out in HMI Berlin and NIST Gaithersburg and NPI Rez on different interferometric facilities at different neutron wavelengths proved that the coherent scattering lengths can be measured with a relative uncertainty of 0.002%.
 Publication:

Physica B Condensed Matter
 Pub Date:
 June 2000
 DOI:
 10.1016/S09214526(00)003537
 Bibcode:
 2000PhyB..283..400V