Search for charge symmetry violation in np elastic scattering

At TRIUMF we are measuring charge symmetry violation in np elastic scattering. If charge symmetry holds the analyzing powers An and Ap are equal. The measurements will therefore determine the difference from zero of ΔA triple bond An - Ap. The measurements are carried out in the vicinity where the analyzing powers cross zero in order to minimize systematic errors. A 350 MeV polarized (Pn ≅ 0.5) or unpolarized neutron beam is incident onto respectively an unpolarized or polarized (Pp ≅ 0.65) target of the butanol frozen spin type. A symmetric (about the beam axis and in the scattering plane) system of proton detectors and neutron arrays records neutron-proton coincidence events. The detection system allows measurements in the centre-of-mass angular range of 50 -90 . (orig.)