You need JavaScript to view this

Positron annihilation in solids: positronium diffusion; Annihilation du positon dans les solides diffusion du positonium

Abstract

The existence of two slow components in life-time spectrum of positron annihilation in silicium, aluminium and alkaline-earth oxides powders is established. These two long mean-lives {approx_equal} 10{sup -9} s and {approx_equal} 10{sup -7} s result from annihilation, inside and outside the grains respectively, of ortho-positronium formed in defects present in ionic crystals investigated. Dynamic behaviour of Ps, so revealed, is analyzed in terms of diffusion in excellent agreement with experiment. Diffusion constants of the order of 10{sup -4} cm{sup 2} sec{sup -1} and mean path before annihilation from 50 to 300 Angstrom are measured. From 100 to 500 K the temperature influence upon diffusion process is effective only in SiO{sub 2} where activation energy is found about 10{sup -2} eV. The p-Ps zero point energy evaluated by angular correlation gives the order of magnitude for defects dimensions and diffusion mean-time. Finally, o-Ps behaviour in space between grains, where its interaction with atmospheric gases can be only detected, is analysed. (author) [French] Nous mettons en evidence l'existence de deux composantes lentes dans le spectre de temps de vie du positon avant annihilation dans des poudres d'oxydes alcalinoterreux d'alumine et de silice. Ces deux longues vies moyennes {approx_equal} 10{sup -9} s et  More>>
Authors:
Paulin, R [1] 
  1. Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires
Publication Date:
Apr 01, 1969
Product Type:
Thesis/Dissertation
Report Number:
CEA-R-3804
Resource Relation:
Other Information: TH: These docteur ES-sciences physiques; 69 refs; PBD: Apr 1969
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANGULAR CORRELATION; ANNIHILATION; DIFFUSION; ELECTRON-POSITRON INTERACTIONS; LIFETIME; POSITRONIUM; POSITRONS
OSTI ID:
20547250
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France); Faculte des Sciences d'Orsay, Universite de Paris, 91 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR04R3804002857
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
[122] pages
Announcement Date:

Citation Formats

Paulin, R. Positron annihilation in solids: positronium diffusion; Annihilation du positon dans les solides diffusion du positonium. France: N. p., 1969. Web.
Paulin, R. Positron annihilation in solids: positronium diffusion; Annihilation du positon dans les solides diffusion du positonium. France.
Paulin, R. 1969. "Positron annihilation in solids: positronium diffusion; Annihilation du positon dans les solides diffusion du positonium." France.
@misc{etde_20547250,
title = {Positron annihilation in solids: positronium diffusion; Annihilation du positon dans les solides diffusion du positonium}
author = {Paulin, R}
abstractNote = {The existence of two slow components in life-time spectrum of positron annihilation in silicium, aluminium and alkaline-earth oxides powders is established. These two long mean-lives {approx_equal} 10{sup -9} s and {approx_equal} 10{sup -7} s result from annihilation, inside and outside the grains respectively, of ortho-positronium formed in defects present in ionic crystals investigated. Dynamic behaviour of Ps, so revealed, is analyzed in terms of diffusion in excellent agreement with experiment. Diffusion constants of the order of 10{sup -4} cm{sup 2} sec{sup -1} and mean path before annihilation from 50 to 300 Angstrom are measured. From 100 to 500 K the temperature influence upon diffusion process is effective only in SiO{sub 2} where activation energy is found about 10{sup -2} eV. The p-Ps zero point energy evaluated by angular correlation gives the order of magnitude for defects dimensions and diffusion mean-time. Finally, o-Ps behaviour in space between grains, where its interaction with atmospheric gases can be only detected, is analysed. (author) [French] Nous mettons en evidence l'existence de deux composantes lentes dans le spectre de temps de vie du positon avant annihilation dans des poudres d'oxydes alcalinoterreux d'alumine et de silice. Ces deux longues vies moyennes {approx_equal} 10{sup -9} s et {approx_equal} 10{sup -7} s resultent respectivement de l'annihilation a l'interieur et a l'exterieur des grains de l'ortho-positonium forme dans certains defauts presents dans les cristaux ioniques etudies. L'analyse des proprietes dynamiques du Ps ainsi revelees, est effectuee en termes de diffusion en excellent accord avec l'experience. Des constantes de diffusion de l'ordre de 10{sup -4} cm{sup 2} sec{sup -1} et des parcours moyens avant annihilation variant de 50 a 300 Angstrom sont ainsi mesures. Entre 100 et 500 K l'influence de la temperature sur le processus de diffusion n'est sensible que dans SiO{sub 2} ou l'energie d'activation est trouvee voisine de 10{sup -2} eV. L'energie de point zero du p-Ps determinee par correlation angulaire fournit en outre l'ordre de grandeur des dimensions des defauts et du temps moyen de diffusion. Les proprietes de l'o-Ps dans l'espace intergranulaire, ou seule son interaction avec l'atmosphere gazeuse est decelee, sont en outre analysees. (auteur)}
place = {France}
year = {1969}
month = {Apr}
}