New features in the systematics of low-spin states in170–178W

Excited states in the range of even tungsten isotopes, from¹⁷⁰W to¹⁷⁸W, populated in the β-decay of^170–178Re parents have been identified using γ-ray singles and coincidence techniques, utilising the high efficiency of a Compton-suppressed array, and conversion electron systems. Many new states at low excitation energies have been identified, complementing the level schemes previously established from in-beam studies. The new states include excited O⁺ states in¹⁷⁰W,¹⁷²W,¹⁷⁴W,¹⁷⁶W and¹⁷⁸W. A large body of data on decay properties, spins and parities, and relative E2 and E0 matrix elements has been obtained. The properties of theK ^π=0⁺ (quasi-β) bands are compared with similar bands observed in light osmium, platinum and mercury isotopes, which have been attributed to shape coexistence.