Cryogenic measurement of alpha decay in a 4π absorber

Abstract

We established Q spectroscopy, a novel method for the study of alpha decay, by combining 4π detection scheme with a low-temperature microcalorimeter. A 4π metal absorber guarantees absolute measurement of radioactivity without energy loss in the source and absorber. As a clear demonstration of Q spectroscopy, the 241Am alpha source enclosed by a thin gold foil was measured below 100 mK. Its resulting energy spectrum has two dominant peaks with 10 keV FWHM. The more dominant one corresponds to the complete absorption of the Q value, the total decay energy, and the less dominant one to γ-ray escapes. Consequential one-to-one correspondence with high-energy resolution appears between mixed radioisotopes and peaks in Q spectroscopy, which will simplify procedures of nuclear material analysis.