SELF-ABSORPTION IN SOURCES PREPARED FOR 4π BETA COUNTING

Abstract

Using the 4πβ-γ coincidence method the self-absorption of 4πβ counting sources prepared by a number of source preparation techniques has been measured for the negatron emitters Cs¹³⁴ (86-kev branch only), Nb⁹⁵, Hg²⁰³, Co⁶⁰, Sc⁴⁶, Rb⁸⁶, Au¹⁹⁸, Na²⁴, and the positron branch of Cu⁶⁴. The self-absorption varied from a few tenths of one per cent to about ten per cent for sources with a mean superficial density of 2 μg/cm² for most of the nuclides studied. Subsidiary experiments were carried out to indicate the variation of self-absorption with source superficial density.