Study of alpha-particle emission probabilities and energies in the decay of 240Pu

In the frame of EUROMET Project No 325 “Analysis of Plutonium Alpha-Particle Spectra”, the isotopic composition of a 238,239,240Pu mixture was measured by mass spectrometry and by high-resolution alpha-particle spectrometry. The latter revealed a discrepancy with published data of the alpha-particle emission probabilities (Pα) and the energies (Eα) of the two major peaks of 240Pu. New values have been derived: Pα1=0.7256 (6), Pα2=0.2735 (7) and Eα1=5168.54 (14) keV, Eα2=5124.10(15) keV, relative to reference peaks of 238Pu and 239Pu