EFFECT OF TEMPERATURE ON THE PENETRATION OF HEAVY keV IONS IN MONOCRYSTALLINE SOLIDS: I. 133Xe IONS IN GOLD

Abstract

The effect of target temperature on the penetration distribution of 40-kev 133Xe+ ions injected into oriented single-crystal gold has been measured from 20 to 295 °K. The penetration was determined by the anodizing–stripping procedure of Whitton and Davies (1964), and the low-temperature irradiations were performed using a special liquid helium cryostat incorporated into the Chalk River isotope separator. The observed influence of temperature is marked. The median range for both [Formula: see text] and [Formula: see text] incidence is a factor of 2 greater at 20 °K than at 295 °K, and the depths beyond which 10−2, 10−3, and 10−4 of the particles travel are, correspondingly, up to a factor of 3 greater at 20 °K. In these two directions, the range of the "perfectly" channeled particle varies with temperature consistently with the exponential dependence predicted by Lehmann and Leibfried (1963). At [Formula: see text] incidence, little channeling appears to occur characteristic of this direction, even at 20 °K; however, a few percent of the ions do have deep penetrations, arising, it is thought, from channeling skew to the [Formula: see text]. Perhaps surprisingly, the [Formula: see text] distribution exhibits a strong temperature dependence, which is suggestive of a lattice effect with higher stopping power than in amorphous material.