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 experim ents due to systematic sources of error. We have used a new method, wh ich eliminates two of the main sources of error, to measure the scatte ring 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 h as an error limit five times lower. (C) 1998 Elsevier Science B.V. All rights reserved.