Stopping powers of havar for protons from 4.0 to 13.0 MeV

Abstract

Stopping powers of havar have been measured with an uncertainty of ±0.35% for protons from 4.0 to 13.0 MeV. Experimental results have been compared with calculated stopping powers obtained by Bragg's additivity rule [W.H. Bragg and R.K. Kleeman, Philos. Mag. 10 (1905) 318] using the stopping-power values for constituent elements calculated by Andersen and Ziegler's formula [Hydrogen Stopping Powers and Ranges in All Elements (Pergamon, New York, 1977)]. The calculated values agree with the experimental results within the stated uncertainty. Applying the modified Bethe-Bloch formula including the Barkas term for the stopping power of compounds, the mean excitation energy, viz., the I-value, for havar has been extracted from the experimental results. In this analysis, we used the theory of Ashley et al. [Phys. Rev. B 5 (1972) 2393; Phys. Rev. A 8 (1973) 2402] to estimate the Barkas correction and Bonderup's [K. Dan. Vidensk. Selsk. Mat. Fys. Medd. 35 (1967) no. 17] and Bichsel's [UCRL Report No. 17538 (1967); ICRU Report 37 (1984)] shell corrections. With Bonderup's shell correction, the I-value is 292.4±6.7 eV; with Bichsel's shell correction 296.9±7.5 eV. These two I-values agree well within the uncertainties.