Progress toward a new measurement of the parity violating asymmetry in n + p → d + γ

Abstract A proof-of-principle experiment using unpolarized low-energy neutron capture on polyethylene and an array of 12 CsI detectors operated in current mode has been performed to test the possibility of measuring at LANSCE the parity-violating asymmetry A γ in the angular distribution of 2.23 MeV gamma rays from the n → + p → d + γ reaction. Results of this experiment including the current mode signal, electronic noise and detector sensitivity to magnetic fields are reported. The motivation and conceptual design for a new experiment aimed at a 10-fold improvement in the accuracy of A γ are outlined.