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Central-field model for the γ spectrum of positrons annihilating on rare-gas atoms

Cheng, Yong Jun and Mitroy, Jim (2014). Central-field model for the &gamma; spectrum of positrons annihilating on rare-gas atoms<br />. Physical Review A: Atomic, Molecular and Optical Physics,90(4 - Article No. 042702):1-12.

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IRMA ID 84377429xPUB13
Title Central-field model for the γ spectrum of positrons annihilating on rare-gas atoms
Author Cheng, Yong Jun
Mitroy, Jim
Journal Name Physical Review A: Atomic, Molecular and Optical Physics
Publication Date 2014
Volume Number 90
Issue Number 4 - Article No. 042702
ISSN 1050-2947   (check CDU catalogue open catalogue search in new window)
Start Page 1
End Page 12
Total Pages 12
Place of Publication United States
Publisher American Physical Society
HERDC Category C1 - Journal Article (DIISR)
Abstract A central field model is used to study the two-photon positron annihilation spectrum for the rare gas atoms He, Ne, Ar, Kr, and Xe at energies close to thermal. Correlation effects are incorporated with a semiempirical polarization potential. The γ spectrum is given, with values reported for individual subshells. The predicted full widths at half-maximum (FWHM) for all systems are typically 5%–20% larger than the experimental values reported using the positron trap at the University of California, San Diego, while, with the exception of neon, generally being 2%–10% smaller than the FWHMs measured at University College London. The detailed spectrum for xenon is reported and the likelihood of core annihilation's making a measurable contribution to the observed Doppler spectrum is discussed. The γ spectra are found to be insensitive to variations in the scattering potential and whether the target is represented by a Hartree-Fock or a Dirac-Fock wave function. The model potential used in the solution of the positron-atom Schrödinger equation provides a reasonable fit to recent total elastic cross-section measurements reported by the Australian National University and University of Trento groups.
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Created: Wed, 19 Aug 2015, 12:29:10 CST