MEDIAN PENETRATION DEPTHS AND IMPLANTATION PROFILES FOR LOW-ENERGY POSITRONS IN AL

New measurements and Monte Carlo simulations for 1-30 keV positron implantation in Al are reported. The annihilation lineshape was measured as a function of positron energy E and the thickness of Al overlayers on a glass substrate. Median implantation depths vary as 117(6) E1.64(2) angstrom, with E in keV. The implantation profiles differ significantly from the widely accepted Gaussian derivative form. The excellent agreement between experiment and simulation confirms the power of the Monte Carlo method in positron (and by implication electron) spectroscopies.