Abstract
-delayed fission (DF) decay of a low-spin (ls) and a high-spin (hs) isomer in was studied at the ISOLDE facility at CERN. Isomer-selective laser ionization and time gating were employed to investigate each isomer separately and their DF partial half-lives were determined: s and s. This work is the first DF study of two states in one isotope and allows the spin dependence of low-energy fission to be explored. The fission fragment mass distribution of a daughter nuclide , following the decay of the high-spin isomer, was deduced and indicates a mixture of symmetric and asymmetric fission modes. Experimental results were compared with self-consistent mean-field calculations based on the finite-range Gogny D1M interaction. To reproduce the measured , the calculated fission barrier of had to be reduced by . After this reduction, the measured was in agreement with calculations for a few possible configurations for . Theoretical DF probabilities for these configurations were found to be lower by a factor of 4–9 than the DF probability of . The fission fragment mass distribution of was compared to the scission-point model SPY and the calculations based on the finite-range liquid-drop model. The first observation of DF for is also reported.
4 More- Received 13 February 2020
- Accepted 20 March 2020
DOI:https://doi.org/10.1103/PhysRevC.102.014319
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society