Shape Coexistence and Electric Monopole Transitions in exp 184 Pt

Levels in exp 184 Pt were studied from the decay of mass-separated exp 184 Au by gamma -ray and conversion-electron spectroscopy and by gamma -ray angular distributions from low-temperature nuclear orientation. In addition to coexisting K exp pi = 0 exp + bands, coexisting K exp pi = 2 exp + bands are observed at low energy. Strong interband electric monopole transitions are observed between states of the two K exp pi = 0 exp + bands and also between states of the two K exp pi = 2 exp + bands. The coexistence of K exp pi = 2 exp + bands at low energy represents a new type of collective structure.