Attenuation of photons at 3-14-keV energies in helium

• Published in: Physical review. A, Atomic, molecular, and optical physics Vol. 51; no. 1; pp. 447 - 453
• Main Authors: Azuma, Y, Berry, HG, Gemmell, DS, Suleiman, J, Westerlind, M, Sellin, IA, Woicik, JC, Kirkland, JP
• Format: Journal Article
• Language: English
• Published: United States 01-01-1995
• Subjects: ATOM COLLISIONS; ATOMIC AND MOLECULAR PHYSICS; ATTENUATION; BASIC INTERACTIONS; CHARGED PARTICLES; COHERENT SCATTERING; COLLISIONS; COMPTON EFFECT; CROSS SECTIONS; ELASTIC SCATTERING; ELECTROMAGNETIC INTERACTIONS; ELEMENTS; ENERGY RANGE; FLUIDS; GASES; HELIUM; INTERACTIONS; IONIZATION; IONS; KEV RANGE; KEV RANGE 01-10; KEV RANGE 10-100; MULTICHARGED IONS; NONMETALS; PHOTOIONIZATION; PHOTON COLLISIONS; PHOTON-ATOM COLLISIONS; RARE GASES; RAYLEIGH SCATTERING; SCATTERING 664200 > Spectra of Atoms & Molecules & their Interactions with Photons > (1992-)
• ISSN: 1050-2947; 1094-1622
• DOI: 10.1103/PhysRevA.51.447

We have measured the total photoattenuation cross section of helium for photons in the energy range of 3--14 keV. At these energies, the photoionization cross section is rapidly decreasing, so that Compton scattering is significant at 4 keV and dominates at the highest energies. Our measurements verify the dominance of Compton scattering in this energy range, and its importance in recent measurements of the ratio of double to single photoionization of helium. The measured cross sections are close to the combined calculated cross sections for Compton scattering and photoionization; we are able to distinguish the contributions of the two effects.