Systematics for the <i>Z</i>₁-oscillation in stopping powers of various solid materials

Abstract

Stopping powers have been measured at common ion velocities v = 0.18 cm ns −1 (v/v 0 = 0.82) and v = 0.22 cm ns −1 (v/v 0 = 1.01) for all projectiles 6 ≤ Z 1 ≤ 20 in five solid materials: carbon, aluminum, nickel, silver, and gold. The Z 1 -oscillation was observed and several new features for the systematics of the oscillation emerge: (i) the amplitude of the oscillation varies with target material and is weak in nickel, (ii) the amplitude changes with ion velocity but this dependence varies with material, (iii) the phase of the oscillation varies by up to 2 units in Z 1 according to the material, and (iv) the phase is independent of the velocity over the range studied.We conclude that at low velocity the effect of projectile (Z 1 ) electronic structure on the stopping power cannot be separated from that of the material (Z 2 ).An apparent variation of the stopping power with target thickness was observed and is interpreted in terms of multiple scattering through a recent theoretical treatment.