First observation of the decay of the 13/2 isomer in Hg and (2) systematics of neutron transitions across the nuclear chart

Hgにおける13/2核異性体の崩壊の初観測、および核図表における中性子遷移の(2)系統性

Huang, H.*; Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Li, Z. H.*; Guo, C. Y.*; Barzakh, A. E.*; Van Duppen, P.*; Andel, B.*; 他33名*

Huang, H.*; Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Li, Z. H.*; Guo, C. Y.*; Barzakh, A. E.*; Van Duppen, P.*; Andel, B.*; 33 of others*

The decay of the 13/2 isomeric state in Hg was observed for the first time following the decay of the 13/2 isomer in Pb produced in the NdCr reaction. Using - delayed coincidence measurements, the half-life of this isomer was measured to be 290(30) s. This isomer is proposed to deexcite by an unobserved low-energy 2 transition to the known 9/2 member of a strongly prolate-deformed 7/2[514] band, followed by a 105-keV 1 transition to the bandhead. A lower limit of B(2)0.018 W.u. was deduced for the unobserved transition. The presumed retardation is proposed to be due to the notable shape change between the initial, nearly spherical, and the final, strongly deformed, states. A similar scenario is also considered for the 13/2 isomer in Hg, suggesting both are cases of shape isomers. The B(2) systematics of neutron transitions across the nuclear chart is discussed.