Deuteron- and Alpha-Induced K-Shell Ionization Cross Section Ratios in the Z=12-17 Region

Experimental deuteron- and alpha-induced K-shell ionisation cross section ratios are presented for elements ranging from Mg to Cl (Z=12-17) in the incident energy range 0.2 to 0.45 MeV/u. The experimental ratios R = ¿¿/4¿d are generally close but slightly higher than the theoretical ratios calculated according to the procedure of Brandt and Lapicki; the largest differences occur for Al and Si where the experimental values are 15-20% too high. The experimental ratios show roughly the same dependence on reduced projectile velocity, ¿= (v1 / vK)(2/¿K), as the theoretical ones in the reduced incident velocity range used in the present work, ¿= 0.45 to ¿=1. This is in opposition to the results previously obtained in the velocity range ¿=0.25 to ¿=0.55 for elements ranging from Ca to Cu (Z=20-29), where the observed ratios are rather independent of the reduced velocity.