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

The {beta}{sup +}/EC decay of a mass-separated {sup 80}Y source has been studied by {beta}- and {gamma}-ray spectroscopy following the bombardment of a thin {sup 24}Mg target with {sup 58}Ni ions at 190 MeV. An extended decay scheme with 14 new states in {sup 80}Sr has been identified including the first observation of negative-parity states. The low-lying positive-parity states have been found to be clustered indicating a pattern of one-, two-, and possibly three-phonon multiplets characteristic of an anharmonic vibrator. Some states in {sup 80}Sr can also be grouped into a {gamma}-vibrational band. In general the low-lying states in light strontium isotopes show vibrationlike collectivity which evolves to rotational behavior with increasing spin and decreasing neutron number. The observed {sup 80}Ythinsp{beta}-decay fragmentation and log ft values have also been used to assign spin and parity of 4{sup {minus}} and 1{sup {minus}} to the parent ground state and the 228.5 keV isomeric state, respectively. {copyright} {ital 1999} {ital The American Physical Society}