STOPPING OF 5-100-KEV HELIUM IN TANTALUM, NIOBIUM, TUNGSTEN, AND AISI-316L STEEL

The stopping power of Ta, Nb, W, and AISI 316L stainless steel for He ions at velocities below the Bohr velocity has been deduced by compari ng the ranges of 5 to 100 keV He+-ions determined with the elastic-rec oil-detection-analysis method with those obtained in molecular dynamic s simulations. The nuclear slowing down was treated through the use of molecular dynamics calculations and a potential obtained from density -functional theory calculations. The comparisons showed that the elect ronic stopping powers given by Ziegler, Biersack and Littmark (The Sto pping Powers and Ranges of Ions in Matter (Pergamon, New York, 1985), Vol. 1 [1], had to be multiplied with a factor of 1.4 for Ta, 1.0 for Nb, 1.1 for W, and 1.0 for AISI 316L. The uncertainty of the factors a nd hence the scaled stopping power values is +/-5%. The total stopping powers were obtained from molecular dynamics simulations in which the modified electronic stopping powers were used.