The Spectrographic Determination of Uranium 235. Part IV. Using a Direct Reading,Littrow,Grating Spectrograph and a Hollow Cathode

Abstract

This report, the fourth of a related series dealing with the isotopic analysis of uranium, describes the use of a hollow cathode source and a 4-m, direct-reading, Bausch and Lomb high-resolution spectrograph. A relative precision of ±3.0%, expressed at the 95% confidence level, was obtained with naturally occurring uranium for a single cathode determination of U²³⁵ measured in twenty min. Evidence for a weak uranium line structure interfering with the U²³⁵ measurement is presented

Minor isotopes, U²³¹ and U²³⁶, present up to a few percent at the higher U²³⁵ concentrations, did not interfere with U²³⁵ measurements. Measurements of U²³⁴, however, could not be made in the presence of high U²³⁵ concentrations, thereby limiting the determination of total uranium necessary for calculating the percent U²³⁵. At the lower U²³⁵ concentrations, the concentrations of minor isotopes are generally too small to significantly affect the total uranium content of the sample.