Studies of observed trends in values of Bethe–Bloch parameters extracted from stopping power measurements

In the course of previous investigations, trends in values of the Bethe–Bloch parameters, mean excitation energy (I) and Barkas-effect parameter (b), have been observed. Generally I values decrease with increasing projectile atomic number (z) whereas b values increase. However, the opposite trends have been previously observed for ZnSe and GaAs targets traversed by ¹H and ⁴He projectiles. In the present study, that opposite trend was also followed when ⁷Li projectiles were included. When selected measurements for ⁴He, ¹²C, ¹⁴N, and ¹⁶O projectiles impinging on Si targets were analyzed, extracted I and b values followed essentially the original trends in z dependence. Stopping power measurements for 12 elemental targets with atomic numbers (Z) lying between 12 and 48 traversed by ²⁹Si projectiles have been analyzed for determination of values of a single effective charge parameter, as part of a continuing study of systematics in such values in terms of both z and Z. Two other sets of measurements featuring ⁷Li projectiles and eight elemental targets with Z values between 5 and 48 have been similarly analyzed. In some of the effective charge studies the data proved amenable to extraction of three parameters, so that results could be included in the ongoing study of z dependences of extracted values of I and b. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004