Accession Number : AD0272604

Title :   THE PHOTOELECTRIC K-ABSORPTION CROSS SECTION OF HELIUM AND LITHIUM

Corporate Author : CORNELL UNIV ITHACA N Y

Personal Author(s) : BAKER,D.J. JR.

Report Date : FEB 1962

Pagination or Media Count : 1

Abstract : The absorption cross section of Helium in the spectral region near the K-edge was measured. Results were in good agreement with calculations. The absorption cross section of Lithium near its K-edge was measured with an uncertainty of 10%. Observations agree with the results of a calculation performed using the published calculations on Helium as a guide. The measurement of the absorption cross section differed from that of previous investigators in that a small cell was used to confine the gas, whereas in other investigations the entire optical path of a gasfilled spectrometer served as the absorbing sample. An advantage which accrues from the use of a gas cell is the possibility of carrying out absorption measurements utilizing a soft x-ray emission band as a source and a photomultiplier as a detector. Such a combination provided an accurate attenuation measurement for Helium at 180 A, the short wavelength end of the spectral range of interest. At all longer wavelengths (200 to 600 A), a condensed spark served as the source of radiation which was detected photographically. (Author)

Descriptors :   *ELECTRON TRANSITIONS, *HELIUM, *LITHIUM, *PHOTONS, *X RAY ABSORPTION ANALYSIS, ABSORPTION, ATOMS, ENERGY, INSTRUMENTATION, PHOTOMULTIPLIER TUBES

Distribution Statement : APPROVED FOR PUBLIC RELEASE