Calculation of the Positron Annihilation Rate in PsH with the Positronic Extension of the Explicitly Correlated Nuclear−Electronic Orbital Method†

2009 ◽  
Vol 113 (16) ◽  
pp. 4004-4008 ◽  
Author(s):  
Michael V. Pak ◽  
Arindam Chakraborty ◽  
Sharon Hammes-Schiffer
Keyword(s):  
Positron Annihilation ◽  
Orbital Method ◽  
Annihilation Rate ◽  
Explicitly Correlated

Complex dependence of the positron annihilation rate on methane gas density and temperature

1975 ◽  
Vol 62 (5) ◽  
pp. 1777-1789 ◽  
Author(s):  
J. D. McNutt ◽  
V. B. Summerour ◽  
A. D. Ray ◽  
P. H. Huang ◽  
D. A. Johnson
Keyword(s):  
Positron Annihilation ◽  
Annihilation Rate ◽  
Gas Density ◽  
Methane Gas ◽  
Complex Dependence

Positron diffusion in krypton and xenon

1982 ◽  
Vol 60 (4) ◽  
pp. 615-617 ◽  
Author(s):  
R. I. Câmpeanu
Keyword(s):  
Positron Annihilation ◽  
Cross Sections ◽  
Time Variation ◽  
Low Energy ◽  
Annihilation Rate ◽  
University College ◽  
University College London ◽  
Experimental Values ◽  
The University ◽  
Theoretical Scattering

The equations describing diffusion of positrons in krypton and xenon are solved with the best theoretical scattering and annihilation data available to date to obtain the time variation of the positron annihilation rate. The theoretical shoulder lengths obtained with the data of McEachran et al. agree well with the experimental values given by the University College London group, while the shoulder lengths obtained with the data of Schrader are much larger. The present results allow for an assessment of the accuracy of the existent low energy e+Kr and e+Xe elastic cross sections.

scholarly journals Positron annihilation rate in single atom with slater type orbital approximation

2013 ◽  
Vol 16 (4) ◽  
pp. 43-51
Author(s):  
Lang Hoang Trinh ◽  
Tao Van Chau ◽  
Chien Hoang Le ◽  
Hong Thi Yen Huynh ◽  
Tram Ngoc Huynh
Keyword(s):  
Positron Annihilation ◽  
Bound States ◽  
Pair Correlation ◽  
Analytical Form ◽  
Single Atom ◽  
Annihilation Rate ◽  
Slater Type ◽  
Slater Type Orbital ◽  
Type Orbital ◽  
Orbital Approximation

A theoretical approximation for the structure of many-positron and manyelectron atoms in bound states is presented. The purpose of this theory is to permit the calculation of positron lifetimes from annihilation enhancement factor which is directly estimated by pair correlation function for each element atom, but not analytical form of correlation functions which depend upon homogeneous electron gas Monte– Carlo simulation data. We therefore used a modified orbital approximation for the electrons and positron. The orbital modification consisting of explicit electronpositron and electron-electron correlation in each elec-tronic orbital was used for the electrons and positron wave functions. The kinetic energies of the electrons and positron were treated on the same footing, and the Born-Oppenheimer approximation was applied to the nuclei. In this paper we treated only those systems for the valance electrons in the real spatial coordinate of the atom or molecule. The complex of many-particle problem was solved by the Schrongdinger of one particle equation which is derived by Kohn–Sham approximation and single particle wave function of Slater type orbital. As a result of this model, the positron annihilation rate and lifetime in some atoms, Ti, Zn and Zr, were calculated.

Positron annihilation in methane gas

1970 ◽  
Vol 48 (24) ◽  
pp. 2984-2990 ◽  
Author(s):  
P. M. Smith ◽  
D. A. L. Paul
Keyword(s):  
Positron Annihilation ◽  
Standard Error ◽  
Room Temperature ◽  
Annihilation Rate ◽  
Effective Number ◽  
Gas Density ◽  
Methane Gas ◽  
Free Positron

The annihilation of positrons in methane gas at room temperature has been measured at pressures below 2 atm. The annihilation rate for the free positron component is proportional to the gas density and corresponds to an effective number of electrons per molecule taking part in annihilation, Zeff = 139.6 ± 1.0 (standard error). The quenching of orthopositronium corresponds to 1Zeff = 0.57 ± 0.07. Resonance annihilation is discussed in a general way.

Investigations of positron-annihilation rate in semimetals

1975 ◽  
Vol 10 (10) ◽  
pp. 1067-1073 ◽  
Author(s):  
N. Wagner ◽  
O. Brümmer ◽  
A. Andreeff ◽  
G. Brauer
Keyword(s):  
Positron Annihilation ◽  
Annihilation Rate

Positron Annihilation Rate at Metal Surfaces

1983 ◽  
Vol 120 (1) ◽  
pp. K27-K31
Author(s):  
K. S. Bhadauria ◽  
S. B. Shriv Astava
Keyword(s):  
Positron Annihilation ◽  
Metal Surfaces ◽  
Annihilation Rate
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