Microscopic description of superallowed alpha-decay transitions

It was recently found that the formation probabilities of alpha particles in Te isotopes are larger than the corresponding probabilities in Po isotopes. We have done a full microscopic calculation within the framework of the multistep shell model to analyze in detail the formation probabilities and subsequent decays of alpha particles from Po-212 and Te-104. We have also calculated the spectra of these two decaying nuclei and found that the tentatively assigned spin (18(+)) at 2.922 MeV in Po-212 (National Nuclear Data Center, www.nndc.bnl.gov) is predicted to be a state 16(+). We also present for the first time the full energy spectrum of Te-104. The evaluated formation amplitudes in both nuclei show that in Te-104 there is indeed a superallowed alpha-decay transition.