First observation of excited states in 173Hg

The neutron-deficient nucleus 173Hg has been studied following fusion-evaporation reactions. The observation of gamma rays decaying from excited states are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighbouring neutron-deficient Hg nuclei. In addition to the gamma-ray spectroscopy, the alpha decay of this nucleus has been measured yielding superior precision to earlier measurements.Comment: 5 pages, 4 figure

Spectroscopy at the two-proton drip line: excited states in 158W

Excited states have been identified in the heaviest known even-Z isotone 158W, which lies in a region of one-proton emitters and the two-proton drip line. The observation of γ-ray transitions feeding the ground state establishes the excitation energy of the yrast 6+ state confirming the spin-gap nature of the α-decaying 8+ isomer. The 8+ isomer is also expected to be unbound to two-proton emission but no evidence for this decay mode was observed. An upper limit for the two-proton decay branch has been deduced as 0.17% at the 90% confidence level. The possibility of observing two-proton emission from multiparticle isomers in nearby nuclides is considered

Characterizing the atomic mass surface beyond the proton drip line via alpha-decay measurements of the pi s(1/2) ground state of Re-165 and the pi h(11/2) isomer in Ta-161

The alpha-decay chains originating from the pi s(1/2) and pi h(11/2) states in Au-173 have been investigated following fusion-evaporation reactions. Four generations of alpha radioactivities have been correlated with Au-173(m) leading to a measurement of the alpha decay of Ta-161(m). It has been found that the known alpha decay of Ta-161, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt gamma rays feeding the ground state of Au-173. This prompt gamma radiation was used to aid the study of the alpha-decay chain originating from the pi s(1/2) state in Au-173. Three generations of alpha decays have been correlated with this state, leading to the observation of a previously unreported activity which is assigned as the decay of Re-165(g). This work also reports the excitation energy of an alpha-decaying isomer in Ta-161 and the Q(alpha) value of the decay of Ta-161(g). DOI:10.1103/PhysRevC.86.06431

Spectroscopy at the two-proton drip line: Excited states in 158W

Excited states have been identified in the heaviest known even-Z isotone 158W, which lies in a region of one-proton emitters and the two-proton drip line. The observation of γ-ray transitions feeding the ground state establishes the excitation energy of the yrast 6+ state confirming the spin-gap nature of the α-decaying 8+ isomer. The 8+ isomer is also expected to be unbound to two-proton emission but no evidence for this decay mode was observed. An upper limit for the two-proton decay branch has been deduced as 0.17% at the 90% confidence level. The possibility of observing two-proton emission from multiparticle isomers in nearby nuclides is considered.peerReviewe