PRECISION MEASUREMENT OF THE MOMENTA OF CONVERSION ELECTRON LINES FROM SOURCES OF 212Pb (ThB)

Abstract

Momentum ratios of some of the more intense internal conversion lines from sources of thorium radioactive deposit have been determined with accuracies of 1 to 4 parts in 10⁵ using an iron-free β spectrometer. Accurate absolute values of the momenta were obtained from intercomparisons of these line momenta with that of the K-412 internal conversion line in ¹⁹⁸Hg. The X-ray self-calibration method of Siegbahn is discussed in some detail and is shown to be less accurate at this time. The results are analyzed on both the 1955 and 1963 least-squares adjusted values of the fundamental constants.