Abstract
The decays of the very neutron rich Sn isotopes were studied at CERN/ISOLDE using isotopic and isobaric selectivity achieved by the use of a resonance ionization laser ion source and mass spectroscopy, respectively. Neutron decay rates, γ-ray singles, and γ-γ coincidence data were collected as a function of time. The half-life and delayed neutron emission probability values of were measured to be 530(20) ms and 21(3)%, respectively. For a of 250(30) ms was determined along with a value of 30(5)%. For a of 190(60) ms and a value of 58(15)% were deduced. Identification of low-energy transitions in was made possible by comparison of laser-on and laser-off γ-ray spectra. Those data combined with γ-γ coincidence spectra were used to construct a level scheme for that includes an unexpectedly low first excited state at 282 keV. A ground state β branch of 33.2% was measured by following the growth and decay of the daughter. Shell-model calculations are consistent with the observed level structure and can account for a lowered first excited state.
- Received 30 June 2001
DOI:https://doi.org/10.1103/PhysRevC.65.034313
©2002 American Physical Society