Fits of non-Rutherford cross sections and their inclusion in the RUMP simulator

It is well known that the cross section for proton scattering from low-Z (2-14) nuclei may be significantly greater than Rutherford. In carbon the resonant enhancement is about 60 times that of the Rutherford predication. Failure to account for this enhancement in modeling programs such as RUMP will lead to a gross overestimate of the carbon present in the sample. We have obtained a numerical approximation to the experimental cross section (≤ 2 MeV) for carbon, nitrogen, fluorine and silicon. These fits have been incorporated in the RUMP simulator. The fitting procedure and inclusion into RUMP should be readily extended to higher energies and other nuclei. Examples of backscattering analyses with the non-Rutherford cross sections will be compared with analyses using the unmodified RUMP and with the experimental spectra. (orig.)