LOW EXITATION LEVELS OF Th$sup 23$$sup 1$

The Th/sup 231/ gamma -ray spectrum was studied with a scgatillation spectrometer with a NaI(Tl) crystal and 7% resolving power on the Cs/sup 137/ 2 line. Gamma quanta coinciding with U/sup 235/ alpha particles were recorded, and the spectra obtained are plotted. The most intense line on the spectrum corresponds to 184 kev. The intensity of the 144-kev line is 25 to 30% that of the 184-kev line. The intensity of unresolved lines in the spectrum from 70 to 110 kev is 40% of the intensity of the line at 184 kev. (R.V.J.)