Stopping powers of Al and Cu for protons from 3 to 9 MeV

The stopping powers of Al and Cu for protons having energies from 3 to 9 MeV have been measured with an accuracy of ±0.4%. The results have been compared with the Risoe and the Aarhus data of Anderson et al. and with Tschalaer's data for Al. The mean excitation energies have been extracted from the present results using the Bonderup shell correction, the Barkas correction and the Bloch correction as 167.4±0.5 eV for Al and 326.3±0.6 eV for Cu. A set of parameters χ=1.340 and b=1.26 was used in these determinations. By using the mean excitation energies thus determined, the Bonderup shell corrections, the Barkas corrections and the Bloch corrections, stopping powers have been calculated up to 30 MeV for Al and up to 20 MeV for Cu. The calculated stopping powers agree very well with the Aarhus data. For Al, the agreement between the calculated stopping powers and Tschalaer's data is surprisingly good up to 30 MeV. (orig.)