ALPHA PARTICLE STUDY OF MADAGASCAR MONAZITE FOR SUPERHEAVY ELEMENTS

ABSTRACT The energy distributions of the alpha particles emitted from two Madagascar monazite specimen were measured. In one of the specimen, the thorium and uranium abundances were measured chemically. The alpha particle energy distribution was in accordance with the thorium and uranium abundances. No alpha particles above 10.6 Mev were observed; even though there were 2.2 × 10 6 alpha counts between 5.45 and 8. 78 Mev from 232 Th daughters. An upper limit of 10 −8 is obtained from these data for the superheavy element abundance associated with a decay chain having a 14 Mev alpha emitter. Thoron, 220 Rn, diffusion out of the monazite was so rapid that sharp lines appeared in the alpha energy distribution. This thoron diffusing into the mica or along fine cracks in the mica would produce giant halos.