The Polarization in Free Neutron-Proton Scattering at 140 MeV

Abstract

The results are presented of an experiment carried out on the CERN synchrocyclotron to measure the polarization in free neutron-proton scattering at an effective energy of 140 ± 2 MeV. The neutron energy spectrum was roughly triangular in shape with a base extending from 100 to 190 MeV. Asymmetries were measured by using a solenoid to precess the neutrons. The neutron beam which was used had a polarization of 0.226 ± 0.010 as determined by small-angle scattering from uranium and lead targets. Measurements of asymmetries in the scattering of the neutrons by liquid hydrogen targets were made at 14 centre-of-mass angles between 20° and 160° using multiple detectors and an electronic system which reduced the systematic uncertainties normally present in the experiments. The results agree well with recent measurements by Kuckes and Wilson using a different technique. Agreement is also found with the phase shift sets YLAN3 and YLAN3M of Hull, Lassila, Ruppel, McDonald and Breit.