A new neutron interferometric method used to measure the scattering length of silicon

The neutron interferometry technique provides a precise and direct way to measure the coherent scattering lengths b of low-energy neutrons, but its potential accuracy has not been fully realized in past experiments due to systematic sources of error. We have used a new method, which eliminates two of the main sources of error, to measure the scattering length of silicon to an accuracy of 0.005%. The resulting value b = 4.1507(2) fm is in agreement with the current accepted value, but has an error limit five times lower. (C) 1998 Elsevier Science B.V. All rights reserved.