Crossed-Beam Measurement of the Electron-Impact Polarization of Helium 4922 Å Optical Radiation
- 5 April 1967
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 156 (1), 55-58
- https://doi.org/10.1103/physrev.156.55
Abstract
Nonzero threshold polarization of helium 4922 Å optical radiation, as first reported by the author, has since been observed by Heddle and Keesing. A recent experiment designed to minimize elastic gas scattering of the electrons has involved He pressures ranging from to Torr, background pressures of 3× Torr, an optical resolution of less than 10 Å half-intensity width, zero-magnetic-field focusing of electrons, and gas scattering of the electron beam of less than 1%. The energy resolution of the electron beam was of the order of 0.2-eV half-intensity width. Customary photon-counting rates varied from background to 100 counts/sec with a background of about 1 count/sec. Thus, obtaining satisfactory counting statistics presented no appreciable problem, except at threshold. The results compare with those reported earlier, suggesting that the energy dependence of the polarization, which dips to a near-threshold minimum of approximately 30%, is a real effect. The observation has not been adequately explained.
Keywords
This publication has 6 references indexed in Scilit:
- Elastic Resonances in Electron Scattering from He, Ne, Ar, Kr, Xe, and HgPhysical Review B, 1965
- Production and Effects of Low-Energy Electrons in HeliumPhysical Review B, 1964
- Resonances in the Inelastic Cross Section of HeliumPhysical Review Letters, 1964
- Cause of the Observed Polarization of Electron-Induced Radiation from HeliumPhysical Review B, 1964
- Cause of the Observed Polarization of Electron-Induced Radiation from HeliumPhysical Review Letters, 1963
- Polarization of Light Resulting from the Excitation of Helium by ElectronsPhysical Review B, 1962