Bremsstrahlung Cross-Section Measurements for 50-kev Electrons

摘要: The dependence of the bremsstrahlung differential cross section on photon energy and angle for 50-kev electrons (${\ensuremath{\beta}}_{0}\ensuremath{\approx}0.4$) incident a 10-\ensuremath{\mu}g/${\mathrm{cm}}^{2}$ gold target 17-\ensuremath{\mu}g/${\mathrm{cm}}^{2}$ aluminum has been determined from measurements made with scintillation spectrometer at angles ranging 10 to 140 degrees. experimental results are compared Sommerfeld-Kirkpatrick-Wiedmann sections multiplied by relativistic correction factor ${(1\ensuremath{-}{\ensuremath{\beta}}_{0}cos\ensuremath{\theta})}^{\ensuremath{-}2}$. For high energies (45 kev), show good agreement theory peak intensity angles, approximately 50 60 degrees aluminum, respectively, but extreme there differences about 50% theory. low (10 discrepancies also increase maximum 30% 40% gold. Good is obtained between experiment over whole angular range 45-kev photons emitted target, when rough estimates retardation screening effects included in values Heitler parameter, $\frac{{\ensuremath{\varphi}}_{\mathrm{rad}}}{\overline{\ensuremath{\varphi}}}$, 5.5\ifmmode\pm\else\textpm\fi{}0.6 6.7\ifmmode\pm\else\textpm\fi{}0.7 theoretical value (including above factor) 6.9 both