The region of decaying nuclei close to Sn offers a unique opportunity to study decays, where the valence nucleons occupy the same orbitals. This might give a rise to exceptionally high -particle preformation factor, leading to very fast decay. This kind of enhanced decay was suggested already in 1965 [1], however, to date there is no confirmation for the existence of this so called superallowed decay. The most enhanced known emitter is Po, however, this case is lacking the symmetry. The decays of Ba, Xe, and Te are expected to compete for the fastest known decay [2].
The astrophysical -process has been proposed to terminate with rapid decays of proton rich tellurium isotopes. The details of the termination depends on the single proton separation energies of antimony isotopes [3]. These energies can be probed indirectly by measuring the proton and -decay energies in this region.
In this presentation, preliminary results of an experiment performed at ATLAS, Argonne National Laboratory, using the Fragment Mass Analyzer (FMA) to study charged-particle decays in the Sn region will be presented.
[1] R. Macfarlane et al., Phys. Rev. Lett. 14, 4 (1965)
[2] P. Mohr, Eur. Phys. J. A 31, 23 (2007)
[3] C. Mazzocchi, et al, Phys. Rev. Lett. 98, 212501 (2007)
This work is supported by the U.S Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.