Electromagnetic decays of excited states in Sg261 (Z=106) and Rf257 (Z=104)
Abstract
An isomeric one-quasineutron state, likely based on the [725]11/2- Nilsson level, was identified in Sg261 by its decay via internal conversion electrons. The state has an excitation energy of ≈200 keV and a half-life of 9.0-1.5+2.0 μs. Sg261 has the highest Z and A of any nucleus in which the electromagnetic decay of an isomeric state was observed to date. A separate experiment was performed on the α daughter nucleus of Sg261, namely Rf257. Spectroscopy of delayed γ rays and converted electrons from Rf257 resulted in the identification of a K isomer at an excitation energy of ≈1125 keV with a half-life of 134.9 ± 7.7 μs. The spin of the isomeric state is tentatively assigned I=21/2,23/2 and the state likely decays to a rotational band built on the [725]11/2- Nilsson level via a ΔK=5 or 6 transition. The present results provide new information on excited states in the transactinide region, which is important for testing models of the heaviest elements.
- Publication:
-
Physical Review C
- Pub Date:
- June 2010
- DOI:
- 10.1103/PhysRevC.81.064325
- Bibcode:
- 2010PhRvC..81f4325B
- Keywords:
-
- 21.10.Tg;
- 23.20.Lv;
- 23.35.+g;
- 27.90.+b;
- Lifetimes;
- gamma transitions and level energies;
- Isomer decay;
- 220<
- =A