Pressure dependence of the angular correlation of positron-annihilation radiation in sodium. [Lifetimes]

Journal Article · Tue Jun 15 04:00:00 EDT 1976 · Phys. Rev., B; (United States)

DOI:https://doi.org/10.1103/PhysRevB.13.5193· OSTI ID:7190076

Gustafson, D R; Willenberg, J D

The pressure dependence of the angular correlation of positron-annihilation radiation in sodium was measured in the range from 4 to 68 kbar. Below 55 kbar the measured value of theta/subF/ was consistent with the predictions of the nearly-free-electron model. Above 55 kbar, theta/subF/ deviated from the nearly-free-electron model, indicating that above 55 kbar the electronic structure of sodium metal may no longer be free-electron-like. The precentage of core annihilations varied smoothly from 30% at 4 kbar to 42% at 68 kbar. As pointed out by Kubica and Stott, this increase in the core-annihilation percentage with pressure allows the measurements of the pressure dependence of the positron lifetime in sodium made by MacKenzie, LeBlanc, and McKee to be explained. The pressure dependence of the enhancement of the electrons at the positron was also examined. Reasonable absolute agreement with the theories of Kahana and Carbotte was observed, but the variation in the ratios of the enhancement coefficients with pressure was not in agreement with the theoretical predictions. (AIP)

• Research Organization: Department of Physics, Wayne State University, Detroit, Michigan 48202
• OSTI ID: 7190076
• Journal Information: Phys. Rev., B; (United States), Journal Name: Phys. Rev., B; (United States) Vol. 13:12; ISSN PLRBA
• Country of Publication: United States
• Language: English

Related Subjects

640303* -- Atomic
Molecular & Chemical Physics-- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METALS
ANGULAR CORRELATION
ANNIHILATION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
CHARGED-PARTICLE TRANSPORT
COLLISIONS
CORRELATIONS
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
INTERACTIONS
LEPTONS
METALS
POSITRON COLLISIONS
POSITRONS
PRESSURE DEPENDENCE
RADIATION TRANSPORT
SODIUM
VERY HIGH PRESSURE