Positron lifetime spectra for the noble gases

Coleman, Peter J.; Griffith, T C; Heyland, G R; Killeen, T. L.

doi:10.1088/0022-3700/8/10/021

Cited by 78 publications

(60 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For helium the many-body theory result is in good agreement with precise variational calculations [75] and with the measurements [6], the discrepancy being less than 5%. For neon, argon and krypton the many-body results are in close agreement with the earlier measurements [6], but differ significantly from the positron-trap results for Ar and Kr [78], and are lower than the polarized orbital calculations [52]. Even assuming an error of 5-10% in the many-body calculations, the results of Iwata et al [78] for Ar and Kr appear to be anomalously high.…”

Section: B Thermally Averaged Z Effsupporting

confidence: 77%

See 1 more Smart Citation

Positron scattering and annihilation on noble-gas atoms

2014

View full text Add to dashboard Cite

Positron scattering and annihilation on noble gas atoms is studied ab initio using many-body theory methods for positron energies below the positronium formation threshold. We show that in this energy range the many-body theory yields accurate numerical results and provides a nearcomplete understanding of the positron-noble-gas-atom system. It accounts for positron-atom and electron-positron correlations, including the polarization of the atom by the positron and the nonperturbative process of virtual positronium formation. These correlations have a large effect on the scattering dynamics and result in a strong enhancement of the annihilation rates compared to the independent-particle mean-field description. Computed elastic scattering cross sections are found to be in good agreement with recent experimental results and Kohn variational and convergent close-coupling calculations. The calculated values of the annihilation rate parameter Z eff (effective number of electrons participating in annihilation) rise steeply along the sequence of noble gas atoms due to the increasing strength of the correlation effects, and agree well with experimental data.

show abstract

Section: B Thermally Averaged Z Effsupporting

confidence: 77%

“…However, the positron-atom interaction and electron-positron correlations have a strong effect on the annihilation rates [4,5]. Experimental studies of positron annihilation in heavier noble gases yield Z eff values that are orders of magnitude greater than those obtained in a simple static-field approximation [6,7].…”

Section: Introductionmentioning

confidence: 99%

Positron scattering and annihilation on noble-gas atoms

2014

View full text Add to dashboard Cite

show abstract

“…The annihilation parameters Z e f f is about 150 for positron temperature 293K (thermal energy ∼ 0.024 eV, momentum ∼ 0.042a −1 o ) which means that at room temperature probability that the positron annihilate is great. The present value of Zeff is less than the measurements of UCL group [29,30] which is 400-450 and the measurements of San Diego group, (Z e f f = 400) [31,32].…”

Section: Resultscontrasting

confidence: 65%

Variational calculation of low-energy positron life time in Xe atoms

Abdel-Mageed

2010

Braz. J. Phys.

View full text Add to dashboard Cite

The least-squares variational method (LSVM) is used for determining trial wavefunctions representing lowenergy positron-xenon elastic scattering, which are used to determine the positron lifetime. The trial function is taken to depend on several adjustable parameters, and is improved iteratively by increasing the number of terms. The bound state wavefunctions are obtained using Hartree-Fock-Slater method. The 2γ-rays annihilation rates of the positron in xenon atoms below Positronuim (Ps) formation threshold are calculated. Polarization potential V pl (r) is applied to enhance annihilation rates and lifetime. The present results of annihilation parameters are consistent with semiempirical, theoretical and experimental results.

show abstract

“…(1969), , Canter (1972), Lee and Jones (1974) and Coleman et af. (1975) for Ar, and by Griffith (1979), Heyland et af. (1982 and Charlton (1985) for Kr and Xe.…”

Section: Introductionmentioning

confidence: 85%

Numerical Simulation of Positron Diffusion in the Heavy Noble Gases Ar, Kr and Xe

Singh¹,

Grover²

1986

Aust. J. Phys.

View full text Add to dashboard Cite

Numerical simulation has been carried out of positron annihilation and diffusion under the influence of an external temperature and electric field in heavy noble gases. The electric field was varied over the range 0-200 V cm -1 amagat -1 (1 amagat ... 2.687 xl 0 19 atoms cm -3), whereas the temperature was varied from 300 to 3000 K. It is observed that the decay constant ZeIT increases with increasing atomic mass of the interacting gases He, Ne, Ar, Kr and Xe, while the diffusion coefficient decreases except in the case of neon.

show abstract

Positron lifetime spectra for the noble gases

Cited by 78 publications

References 20 publications

Positron scattering and annihilation on noble-gas atoms

Positron scattering and annihilation on noble-gas atoms

Variational calculation of low-energy positron life time in Xe atoms

Numerical Simulation of Positron Diffusion in the Heavy Noble Gases Ar, Kr and Xe

Contact Info

Product

Resources

About