$\gamma$-ray spectra and enhancement factors for positron annihilation spectra with core-electrons

Abstract

Many-body theory is developed to calculate the $\gamma$-spectra for positron annihilation with valence and core electrons in the noble gas atoms. A proper inclusion of correlation effects and core annihilation provides for an accurate description of the measured spectra [Iwata \textit{et al.}, Phys. Rev. Lett. {\bf 79}, 39 (1997)]. The theory enables us to calculate the enhancement factors ${\gamma }_{nl}$, which describe the effect of electron-positron correlations for annihilation on individual electron orbitals $nl$. We find that the enhancement factors scale with the orbital ionization energy $I_{nl}$ (in electron-volt), as ${\gamma }_{nl}=1+\sqrt{A/I_{nl}}+(B/I_{nl}{)}^{\beta }$, where $A\approx 40$~eV, $B\approx 24$~eV and $\beta \approx 2.3$.

5 pages, 5 figures

References in corpus (2)

• Many-body theory of positron-atom interactions
• Positron scattering and annihilation on noble gas atoms

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