A new isomeric state in 218Pa

摘要

The decay of218Pa was investigated by means ofαandγspectroscopy. The nucleus was produced in the fusion reaction40Ar+182W and separated in flight by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure). The knownαdecays of218Pa were measured with improved precision and newly assigned to be originating from the ground state, which clarified the ambiguities in their previous assignments. In addition, a new isomeric state in218Pa decaying withα-particle energies of 9691(15) keV, 9595(21) keV and a half-life of135?32+62μs was identified. The spins and parities of the involved states were tentatively assigned on the basis of the systematicα-decay properties of the odd-protonN=127isotones and shell model calculations.