Decays Of In-131, Sn-131, And The Position Of The H1(1/2) Neutron Hole State

The decays of the three isomers of In-131 and the total decay energies of the two isomers of Sn-131 have been studied in high sensitivity experiments at the OSIRIS mass separator. The main purpose of the investigation was to determine the position of the neutron hole h(11/2) state, since a previous determination appeared to be in error. The present results support a small separation of the d(3/2) and h(11/2) neutron hole states. The new value obtained from measurements of decay energies is 69+/-14 keV. A more precise value of 65.1 keV may be deduced from the level scheme of Sn-131 obtained currently, however without firm support from coincidence data. This relatively low excitation energy of the h(11/2) state is in agreement with systematics and in disagreement with the previous determination. A re-evaluation of the Q(beta) values and isomer spacings of In-131 has been made.