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 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.

Positron annihilation in methane

1977 ◽  
Vol 55 (3) ◽  
pp. 235-239 ◽  
Author(s):  
A. C. Mao ◽  
D. A. L. Paul
Keyword(s):  
Electric Field ◽  
Positron Annihilation ◽  
Applied Electric Field ◽  
Room Temperature ◽  
Positive Energy ◽  
Annihilation Rate ◽  
Linear Region ◽  
Gas Density ◽  
Single Level ◽  
Made In

Measurements of positron annihilation rates at room temperature under the influence of an applied electric field have been made in methane at different pressures. The experiments were all carried out in the linear region in which the annihilation rate is accurately proportional to gas density. We find Zeff = 142.7 ± 2.0 at 21 °C and zero electric field. At 1000 Torr Zeff decreases linearly with the electric field, the gradient being about 2.5 × 10−2 per (V cm−1 atm−1) at that temperature. The results repudiate the idea of a positive energy single level Breit–Wigner resonance as being responsible for the high value of Zeff, and in this sense are in agreement with the findings of McNutt, Summerour, Ray, and Huang.

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 Methane Gas Density Monitoring and Predicting Based on RFID Sensor Tag and CNN Algorithm

Electronics ◽  
2018 ◽  
Vol 7 (5) ◽  
pp. 69 ◽  
Author(s):  
Chunlei Zhang ◽  
Yuhua Fu ◽  
Fangming Deng ◽  
Baoquan Wei ◽  
Xiang Wu
Keyword(s):  
Gas Density ◽  
Methane Gas

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.

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
Sign in / Sign up

Export Citation Format

Share Document