Probing the positron moderation process using high-intensity, highly polarized slow-positron beams

• Published in: Physical review. A, General physics Vol. 29; no. 1; pp. 96 - 105
• Main Authors: Van House, J., Zitzewitz, P. W.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS American Institute of Physics 01-01-1984
• Subjects: Atomic and molecular collision processes and interactions; Atomic and molecular physics; Electron scattering; Exact sciences and technology; Nuclear And High-Energy Physics; Physics; Electron atom collision; Molybdenum Atoms; Energy distribution; Electron beam; Experimental study; Tungsten Atoms; Platinum Atoms; Solid state; Electron molecule collision; Intermediate energy; Tantalum Atoms; Inelastic scattering; Angular distribution; Electron polarization; Magnesium Oxides; Positron
• ISSN: 0556-2791
• DOI: 10.1103/physreva.29.96

A highly polarized (P = 0.48 + or - 0.02) intense (500,000/sec) beam of 'slow' (Delta E = about 2 eV) positrons (e+) is generated, and it is shown that it is possible to achieve polarization as high as P = 0.69 + or - 0.04 with reduced intensity. The measured polarization of the slow e+ emitted by five different positron moderators showed no dependence on the moderator atomic number (Z). It is concluded that only source positrons with final kinetic energy below 17 keV contribute to the slow-e+ beam, in disagreement with recent yield functions derived from low-energy measurements. Measurements of polarization and yield with absorbers of different Z between the source and moderator show the effects of the energy and angular distributions of the source positrons on P. The depolarization of fast e+ transmitted through high-Z absorbers has been measured. Applications of polarized slow-e+ beams are discussed.