α-particle stopping cross section of gold and silver as measured from thick targets

Stopping cross sections of $\alpha$ particles in Au and Ag have been obtained for $0.3\le E_{\alpha }\le 2.0$ MeV. The experimental method consists of measuring the energy spectra of $\alpha$ particles elastically scattered from thick targets. The experimental details as well as the method for extracting the stopping cross section from measured energy spectra are discussed. The results are found to be in good agreement with those previously obtained using thin targets.