Impact parameter dependent K-shell ionisation of argon by protons scattered over large angles

The K-shell ionisation probability of argon has been measured for protons scattered over angles between 8 and 127.50 and with initial energies of 500 and 750 keV. An increase of this probability has been found when going from scattering angles of 900 and less to the largest observed scattering angle. The asymmetry parameter B in the angular dependence I(theta) = A(1 + B cos theta) has slightly larger, negative values than those measured previously by other workers for copper and aluminium. (author)