Scattering length measurements from radiative pion capture and neutron-deuteron breakup

Abstract The neutron-neutron and neutron-proton 1 S 0 scattering lengths a nn and a np , respectively, were determined simultaneously from the neutron-deuteron breakup reaction. Their comparison with the recommended values obtained from “two-body” reactions gives a measure of the importance of three-nucleon force effects in the three-nucleon continuum. In order to check on the result obtained for a nn from the “two-body” π − - d capture reaction, a new measurement was performed at LANL. Preliminary results of the three experiments are given.