Range anddEdxof C, N, O, F, and Ne in Be and C from 500 keV to 2 MeV

Abstract

Ranges of C, N, O, F, and Ne in Be and of O and Ne in C have been measured with an accuracy of 3.4 to 9.2% in energy intervals of 100 to 150 keV in the energy region from 500 keV to 2 MeV. Additional measurements from 200 to 500 keV have been made for C and O in Be and for O in C. The results are compared with the Lindhard-Scharff-Schiøtt theory and with a range obtained by numerically integrating a ${\left(\frac{\mathrm{dE}}{\mathrm{dx}}\right)}_{\mathrm{total}}$ obtained by adding Firsov's prediction of $\frac{\mathrm{dE}}{\mathrm{dx}}$ due to electronic excitation to the LSS prediction of $\frac{\mathrm{dE}}{\mathrm{dx}}$ for elastic nuclear scattering. The experimental ranges at the low-energy end agree within experimental accuracy to the LSS theory for F and Ne in Be and for Ne in C, but the C-in-Be measurements disagree by as much as 29%. At the high-energy end the disagreement varies from 11% for Ne in C to 24% for O and N in Be. The experimental values are always lower than the theoretical values; but the LSS theory does give the correct relative magnitudes of the ranges, though only qualitatively. In comparison with the Firsov predictions, the over-all disagreement is no worse than 13% for C and N in Be and for O in C, but is as high as 30-37% for F and Ne in Be. The corresponding stopping powers are obtained by differentiating the range-energy curves. At any energy O, F, and Ne in Be and Ne in C have nearly the same $\frac{\mathrm{dE}}{\mathrm{dx}}$, while the $\frac{\mathrm{dE}}{\mathrm{dx}}$ of O in C is the lowest. These derived $\frac{\mathrm{dE}}{\mathrm{dx}}$ values generally agree with the directly measured values and are 2 to 30% higher than the LSS predictions. The derived $\frac{\mathrm{dE}}{\mathrm{dx}}$ values are lower than the Firsov predictions by 2 to 42%, with the difference between theory and experiment tending to increase with increasing atomic number of the ion.