Authors
Huang, H.; Zhang, W.; Andreyev, A.; Liu, Z.; Seweryniak, D.; Li, Z; Guo, C.; Barzakh, A.; Van Duppen, P.; Andel, B.; Carpenter, M. P.; Copp, P.; Huang, T.; Kondev, F. G.; Lauritsen, T.; Reviol, W.; Savard, G.; Stolze, S.
Abstract
The decay of the 13/2(+) isomeric state in Hg-183 was observed for the first time following the a decay of the 13/2(+) isomer in Pb-187 produced in the Nd-142(Cr-50, 2p3n) reaction. Using alpha - gamma delayed coincidence measurements, the half-life of this isomer was measured to be 290(30) mu s. This isomer is proposed to deexcite by an unobserved low-energy M2 transition to the known 9/2(-) member of a strongly prolate-deformed 7/2(-)[51 band, followed by a 105-keV M1 transition to the bandhead. A lower limit of B(M2) >= 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-18(1), suggesting both are cases of shape isomers. The B(M2) systematics of neutron transitions across the nuclear chart is discussed.