Radioactive decay of Y-80 and low-lying states in Sr-80

The beta(+)/EC decay of a mass-separated Y-80 source has been studied by be ta- and gamma-ray spectroscopy following the bombardment of a thin Mg-24 ta rget with Ni-58 ions at 190 MeV. An extended decay scheme with 14 new state s in Sr-80 has been identified including the first observation of negative- parity states. The low-lying positive-parity states have been found to be c lustered indicating a pattern of one-, two-, and possibly three-phonon mult iplets characteristic of an anharmonic vibrator. Some states in Sr-80,an al so be grouped into a gamma-vibrational band. In general the low-lying state s in light strontium isotopes show vibrationlike collectivity which evolves to rotational behavior with increasing spin and decreasing neutron number. The observed 80Y beta-decay fragmentation and log ft values have also been used to assign spin and parity of 4(-) and 1(-) to the parent ground state and the 228.5 keV isomeric state, respectively. [S0556-2813(99)01601-5].