Angular correlation of two-photon positron annihilation in hydrogen gas

1979 ◽  
Vol 57 (7) ◽  
pp. 1027-1030 ◽  
Author(s):  
J. W. Darewych
Keyword(s):  
Wave Function ◽  
Angular Correlation ◽  
Molecular Hydrogen ◽  
Hydrogen Gas ◽  
Annihilation Radiation ◽  
Annihilation Rate ◽  
Two Photon ◽  
State Approximation ◽  
The One ◽  
Photon Annihilation

The expression for the angular correlation of two-photon annihilation radiation for positrons colliding with molecular hydrogen is derived. The one-state approximation is used, and a one-centre expansion of the hydrogen wave function is assumed. Results obtained using a simple H2 wave function yield a half-width of the angular distribution which is in agreement with the observed results for positrons annihilating in liquid hydrogen. Comparison is made with corresponding results for the annihilation rate.

The Polarizability of Molecular Hydrogen H2

1936 ◽  
Vol 32 (2) ◽  
pp. 260-264 ◽  
Author(s):  
C. E. Easthope
Keyword(s):  
Wave Function ◽  
Perturbation Theory ◽  
Molecular Hydrogen ◽  
Applied Field ◽  
Minimum Energy ◽  
Wave Functions ◽  
The Other ◽  
System A ◽  
The One ◽  
Two Parameter

1. The problem of calculating the polarizability of molecular hydrogen has recently been considered by a number of investigators. Steensholt and Hirschfelder use the variational method developed by Hylleras and Hassé. For ψ0, the wave function of the unperturbed molecule when no external field is present, they take either the Rosent or the Wang wave function, while the wave functions of the perturbed molecule were considered in both the one-parameter form, ψ0 [1+A(q1 + q2)] and the two-parameter form, ψ0 [1+A(q1 + q2) + B(r1q1 + r2q2)], where A and B are parameters to be varied so as to give the system a minimum energy, q1 and q2 are the coordinates of the electrons 1 and 2 in the direction of the applied field as measured from the centre of the molecule, and r1 and r2 are their respective distances from the same point. Mrowka, on the other hand, employs a method based on the usual perturbation theory. Their numerical results are given in the following table.

Two-photon annihilation radiation in strong magnetic field

1988 ◽  
Vol 8 (2-3) ◽  
pp. 573-576
Author(s):  
P.G. Mamradze ◽  
A.D. Kaminker ◽  
G.G. Pavlov
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Annihilation Radiation ◽  
Two Photon ◽  
Photon Annihilation

scholarly journals The Intriguing Case of the One‐Photon and Two‐Photon Absorption of a Prototypical Symmetric Squaraine: Comparison of TDDFT and Wave‐Function Methods

ChemPhotoChem ◽  
2019 ◽  
Vol 3 (9) ◽  
pp. 778-793 ◽  
Author(s):  
Francisco J. Avila Ferrer ◽  
Celestino Angeli ◽  
Javier Cerezo ◽  
Sonia Coriani ◽  
Alessandro Ferretti ◽  
...  
Keyword(s):  
Wave Function ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
The One

Two-photon momentum density and angular correlation of positron annihilation radiation in Pd and PdH

1986 ◽  
Vol 34 (2) ◽  
pp. 853-858 ◽  
Author(s):  
Anjali Kshirsagar ◽  
D. G. Kanhere ◽  
R. M. Singru
Keyword(s):  
Positron Annihilation ◽  
Angular Correlation ◽  
Momentum Density ◽  
Annihilation Radiation ◽  
Photon Momentum ◽  
Two Photon

On the Angular Distribution of Two-Photon Annihilation Radiation

1950 ◽  
Vol 77 (2) ◽  
pp. 205-212 ◽  
Author(s):  
S. DeBenedetti ◽  
C. E. Cowan ◽  
W. R. Konneker ◽  
H. Primakoff
Keyword(s):  
Angular Distribution ◽  
Annihilation Radiation ◽  
Two Photon ◽  
Photon Annihilation

Two-photon annihilation rate of the positronic HCN molecule

2012 ◽  
Vol 111 (2) ◽  
pp. 345-352 ◽  
Author(s):  
Małgorzata M. Wołcyrz ◽  
Krzysztof Strasburger ◽  
Henryk Chojnacki
Keyword(s):  
Annihilation Rate ◽  
Two Photon ◽  
Photon Annihilation

Positron Annihilation and the Band Structure in Molybdenum

1972 ◽  
Vol 50 (15) ◽  
pp. 1777-1781 ◽  
Author(s):  
S. M. Kim ◽  
W. J. L. Buyers
Keyword(s):  
Wave Function ◽  
Band Structure ◽  
Angular Correlation ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Plane Waves ◽  
Interpolation Scheme ◽  
Accurate Representation ◽  
Two Photon ◽  
Positron Wave Function

Measurements have been made of the two-photon angular correlation from positrons annihilating in single-crystal molybdenum at room temperature. By means of a combination of conventional slits and Soller slits the number of annihilations for which the momentum lies along a line in the momentum distribution is obtained, and results are presented for the [ζ,ζ,0], [0,0,ζ, and [ζ,ζ,0.71] directions. Theoretical calculations of the angular correlation have been made based on the interpolation or pseudopotential scheme with s–d interaction included. The parameters of the interpolation scheme have been chosen so that an accurate representation is obtained of the APW band structure of Mattheiss. The positron wave function has been obtained in terms of 141 plane waves. The width of the calculated two-photon angular correlation is found to be much broader than the experimental width unless the relative s and d enhancement is considered.

scholarly journals Thermal Cyclotron and Annihilation Radiation in Strong Magnetic Fields

1994 ◽  
Vol 147 ◽  
pp. 550-554
Author(s):  
V.G. Bezchastnov ◽  
A.D. Kaminker
Keyword(s):  
Particle Number ◽  
Spectral Component ◽  
Particle Number Density ◽  
Annihilation Radiation ◽  
Number Density ◽  
Thermal Electron ◽  
Strong Magnetic Fields ◽  
Electron Positron ◽  
The One ◽  
Photon Annihilation

AbstractThe cyclotron and the one-photon annihilation emissions are investigated for a strongly magnetized thermal electron-positron plasmas. The annihilation spectral component is significant when the particle number density N exceeds some critical value, Ncr(T,B). For T ~ 108 − 109 K and B ~ 1012 − 1013 G, this condition can be fulfilled at N < 1022 cm−3, which is realistic for neutron star magnetospheres.

Three-Photon Annihilation of Ortho-Positronium in Argon Gas

1973 ◽  
Vol 51 (5) ◽  
pp. 537-548 ◽  
Author(s):  
H. M. B. Bird ◽  
G. Jones
Keyword(s):  
Exponential Decay ◽  
Annihilation Rate ◽  
Density Range ◽  
Quenching Rate ◽  
Two Photon ◽  
A Value ◽  
Coincidence System ◽  
Positronium Annihilation ◽  
Free Positron ◽  
Photon Annihilation

Marked deviations from simple exponential decay are known to characterize the two-photon annihilation of positrons in the noble gases. In this experiment, a quadruple coincidence system was used to examine the detailed shape of three-photon positron lifetime spectra in argon. No deviation from a simple exponential was observed over the density range 2.57 to 33 amagat, except when a high electric field was applied. The ability to distinguish three-photon ortho-positronium annihilation from other modes of positron annihilation permitted, for the first time, a detailed investigation of the density dependence of the annihilation of ortho-positronium in a simple monatomic gas. Over the whole density range, the ortho-positronium annihilation rate was found to depend linearly on density, with a value of 7.15 ± 0.10 μs−1 for the vacuum rate of ortho-positronium annihilation and 0.250 ± 015 μs−1 amagat−1 for the quenching rate of positronium in argon. With a field of 125 V cm−1 amagat−1 (at 2.57 amagat), a deviation from simple exponential decay was observed, a deviation whose shape is shown to be consistent with an interpretation in terms of time-delayed enhanced positronium production from the equilibrium free positron population.

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