Range measurements in oriented tungsten single crystals. III. The influence of temperature on the maximum range

Abstract

The maximum range, R_max, of ⁴²K ions along the axis in tungsten has been measured over the temperature region 30–725 °K, by means of the anodizing/stripping technique. The results show that R_max is completely independent of the lattice temperature, within an experimental precision of ± 3%. The prominent supertail (~10%) observed in ⁴²K range distributions at 30 °K interferes with the evaluation of R_max. This tail, however, can be completely suppressed by subsequently bombarding the crystal with a higher dose (3 × 10¹⁵/cm²) of Ne ions of similar energy while still at ~30 °K.The main conclusions derived from this series of three papers on range measurements in tungsten single crystals are briefly outlined. We find that R_max is an extremely useful experimental parameter for characterizing the range distribution of channeled ions. Its value in tungsten is determined almost entirely by electronic stopping, except at energies less than a few keV. The electronic stopping powers derived from the energy dependence of R_max agree roughly with theoretical predictions; however, the observed stopping power values exhibit large oscillations about the smooth theoretically predicted dependence on Z₁, the atomic number of the projectile. An adequate explanation of these Z₁ oscillations is not yet available.