Speaker
Description
In a stellar plasma where atoms get partially or fully ionized, the well known continuum β− decay is not the only option. Nuclear β− decay to the bound states of the ionized atom is another probable channel. The β− decay half-life of an atom can even fall drastically due to the opening of this new channel which in tern may affect the nucleosynthesis process.
In our recent study we have studied the β− decay rates to the continuum as well as bound state of some fully ionized atoms of astrophysical interest, in the mass range (A ≈ 60 - 240), where information for neutral atom experimental half-life and β− decay branchings are terrestrially available. Most importantly the study of effective half-lives for bare atoms will be helpful to set a limit for the maximum enhancement in β− decay rate due to the effect of bound state decay channels. Moreover, we have also observed the effect of different nuclear structure and decay inputs (Q value, radius etc.) over the bound to continuum decay rate ratio. Our study indicates the decay rate to bound state of daughter atom becomes larger as the neutral atom Q value becomes lower. Also we found that there must be an increment of decay rate in case of bare atom in comparison with neutral atom.
Most importantly, an interesting phenomenon of changes in β− decay branching for a number of bare atoms has been observed, for the first time. We have found that, for β− decay from a parent level to daughter levels, the ratio of β− decay rate in fully ionized (bare) to neutral atom increases with decreasing Q value and that effects the β− decay branching from the parent level to the daughter levels. Even, sometime the branching scenario may flip in bare atom in comparison with neutral atom due to this phenomenon. Our calculations suggest this branching flip phenomenon can occur in bare 134Cs and 228Ra atoms. Verification of this branching change phenomenon in bare atom decay might be of interest for future experiments.
