Positron bremsstrahlung

Abstract

Numerical results from a calculation of the positron bremsstrahlung spectrum in a partial-wave expansion are presented for $Z=8\mathrm{}$, 92 at photon energies 10, 50, and 500 keV. Data are presented both for a point-Coulomb potential and for a screened Hartree-Slater central potential. Comparison is made with the corresponding electron bremsstrahlung. In the point-Coulomb case the nonrelativistic Sommerfeld formula or the Elwert factor provides a quantitative prediction of the ratio of the two spectra for $Z=8\mathrm{}$, qualitative for $Z=92\mathrm{}$; similar accuracy is achieved in the screened case with a ratio of screened normalization. The positron spectrum is strongly suppressed for low-energy positrons, which cannot penetrate toward the repulsive central potential. For high-energy positrons or long-distance interactions the positron spectrum approaches the electron spectrum.