SEARCH FOR CHARGE-SYMMETRY VIOLATION IN NP ELASTIC-SCATTERING

At TRIUMF we are measuring charge symmetry violation in np elastic sca ttering. If charge symmetry holds the analyzing powers An and A(p) are equal. The measurements will therefore determine the difference from zero of DELTAA = A(n) - A(p). The measurements are carried out in the vicinity where the analyzing powers cross zero in order to minimize sy stematic errors. A 350 MeV polarized (P(n) congruent-to 0.5) or unpola rized neutron beam is incident onto respectively an unpolarized or pol arized (P(p) congruent-to 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 coincid ence events. The detection system allows measurements in the centre-of -mass angular range of 50-degrees-90-degrees.