Calculation of pair production by photons of energies near threshold on atoms

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Physical Review A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.50.343· OSTI ID:7233065

Tseng, H K ^[1]

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1. Department of Physics, National Central University, Chung-Li, Taiwan 32054 (Taiwan, Province of China)

We calculated numerically in a relativistic partial-wave formulation the positron energy spectra of pair-production [sigma]([ital E][sub +]) in the field of atoms with atomic number [ital Z]=1, 6, 13, and 82 for photons of energies near threshold, [ital k]=2.001, 2.01, and 2.10 [ital m][sub [ital e]][ital c][sup 2], where [ital E][sub +] is the positron energy. Our results indicate that in this low-photon-energy region, the atomic-electron screening effect increases as [ital Z] increases, [ital k] decreases, and [ital E][sub +] decreases. The ratio of screened to point-Coulomb cross sections [sigma]([ital E][sub +]) varies from 0.985 to 1.69[times]10[sup 4]. When the screening effect is important, it increases the cross section [sigma]([ital E][sub +]). Our results also indicate that the approximate treatment of screening through energy-shift screening theory becomes inadequate when the screening effect is very important. The approximate treatment of screening through the corrected-effective normalization screening theory works fine in this low-photon-energy region, except for the case with [ital Z]=6, [ital k]=2.001[ital m][sub [ital e]][ital c][sup 2], and [ital E][sub +]=1.0001[ital m][sub [ital e]][ital c][sup 2], where the screening effect is not a normalization effect.

• OSTI ID: 7233065
• Journal Information: Physical Review A; (United States), Journal Name: Physical Review A; (United States) Vol. 50:1; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

664200* -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
ATOM COLLISIONS
ATOMIC NUMBER
COLLISIONS
CORRELATIONS
CROSS SECTIONS
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
ENERGY RANGE
ENERGY SPECTRA
FERMIONS
INTERACTIONS
LEPTONS
MATRIX ELEMENTS
MATTER
PAIR PRODUCTION
PARTIAL WAVES
PARTICLE PRODUCTION
PHOTON COLLISIONS
PHOTON-ATOM COLLISIONS
POSITRONS
RELATIVISTIC RANGE
SPECTRA
THRESHOLD ENERGY