Precision Measurement of Charge Symmetry Breaking in np Elastic Scattering at 347 MeV

Charge symmetry breaking in {ital np} elastic scattering at 347 MeV has been measured with high precision. From fits of the measured asymmetry curves over the angular range 53.4{degree}{le}{theta}{sub c.m.}{le}86.9{degree}, the difference in the center-of-mass zero-crossing angles of the analyzing powers was determined to be 0.438{degree}{plus_minus}0.054{degree}(stat){plus_minus}0.051{degree}(syst). Using the experimentally determined slope of the analyzing power, {ital dA}/{ital d}{theta}=({minus}1.35{plus_minus}0.05){times}10{sup {minus}2} deg{sup {minus}1}, this is equivalent to {Delta}{ital A}=[59{plus_minus}7(stat){plus_minus}7(sys){plus_minus}2(syst)]{times}10{sup {minus}4}. Predictions of nucleon-nucleon interaction models based on meson exchange agree well with this result.