| Abstract: | The authors have carried out the gamma-ray spectrometry of some Vesuvius lavas, by means of a S.E.L.O. equipment which consists of a 100 channels analyzer joined to a photomultiplier tube annexed to aNaI(T1) phosphor. TheU 238,Th 232,Ra 226 andK 2 O contents have been determined and the following conclusions have been drawn: theU 238 seems to be present in the examined lavas and the contents are fairly equal within the errors; also theTh 232 andK 2 O contents show no sensible variations in the different lavas. TheRa 226 content is remarkably higher than that necessary for the equilibrium with the observedU 238 content and shows a decrease with the age of the lavas. TheRa 226 content which exceeds that necessary for the equilibrium with the observedU 238 content decreases with a law similar to the natural radioactive decay ofRa 226. |
