Observation of isomeric decays and the high spin states in doubly-odd 208Fr

TL;DR

This study observed high spin states and isomeric decays in doubly-odd 208Fr nuclei produced via fusion-evaporation, measuring new isomeric half lives and analyzing their nuclear structure.

Contribution

First observation of multiple isomeric states and their half lives in 208Fr, providing new experimental data on high spin nuclear states.

Findings

Measured half lives of 194 keV and 383 keV isomers as 233 ns and 33 ns.

Identified gamma-ray transitions associated with high spin states.

Compared experimental half lives with single particle estimates.

Abstract

Neutron deficient isotopes of Francium (Z=87, N=121-123) as excited nuclei were produced in the fusion-evaporation reaction: 197Au(16O,xn)[213-x]Fr at 100 MeV. The gamma-rays from the residues were observed through the high sensitivity Germanium Clover detector array INGA. The decay of the high spin states and the isomeric states of the doubly-odd 208Fr nuclei, identified from the known sequence of ground state transitions, were observed. The half lives of the 194(2) keV isomeric transition, known from earlier observations, was measured to be 233(18) ns. A second isomeric transition at 383(2) keV and half life of 33(7) ns was also found. The measured half lives were compared with the corresponding single particle estimates, based on a the level scheme obtained from the experiment.