Stopping powers of sup 7 Li, sup 11 B, sup 12 C, sup 14 N, and sup 16 O ions in C sub 16 H sub 14 O sub 3 polycarbonate

The stopping powers of bisphenol {ital A}-polycarbonate C{sub 16}H{sub 14}O{sub 3} for {sup 7}Li, {sup 11}B, {sup 12}C, {sup 14}N, and {sup 16}O ions in the 0.5--2.1-MeV/amu energy region have been determined. To avoid direct beam exposure on the film, a modified transmission geometry was used. The areal density of the foil, at exactly the position where the stopping power data were measured, was obtained by combining weighing and proton energy-loss measurements. The experimental stopping powers are compared with predictions of three semiempirical models, which are based on the heavy-ion scaling rule, and with our previous data for the same ions in Mylar. The systematics and deviations of the data from the predicted stopping powers, and the validity of Bragg's additivity rule, are discussed.