Absolute CKx-ray production cross sections for 0.29-16.0-MeV protons on thin carbon foils

Absolute carbon $K$ x-ray production cross sections (${\sigma }_{K\mathrm{x}}$) have been measured for 0.29-16.0-MeV protons on thin carbon foils, covering the region below the maximum in ${\sigma }_{K\mathrm{x}}$ up to the high-velocity region described by asymptotic (Bethe) theory. An experimental fluorescence yield value ${\omega }_K=(2.46\mathrm{}\pm 0.35)\times {10}^{-3\mathrm{}}$ was determined for carbon. Experimental values of ${\sigma }_K$ are compared to the BEA, SCA, PWBA, and asymptotic theory predictions. At energies close to the maximum in ${\sigma }_K$ (∼0.5 MeV) the BEA predictions were in good agreement with experiment, while at higher energies the PWBA predictions gave the best agreement. Predictions of asymptotic theory lay somewhat below experiment. The measurements show the predicted $\frac{\left(\ln E\right)}{E}$ dependence at higher energies, and experimental values for the two main parameters of the asymptotic theory, viz., $M_{\mathrm{tot}}^2=0.87\mathrm{}$ and $C_{\mathrm{tot}}=8.5\mathrm{}$ (both ± 20%) were derived from a fit to the data. These values are the first of their kind determined by ion bombardment.