Nuclear Seminar - Adam Broniš (1.6.2022)
Wednesday 1.6.2022 at 14:00, Lecture room F1/111
Mgr. Adam Broniš:
Electron capture decay in the transfermium region – studies of 253No, 254No and 254Md
Abstract:
All so far synthesized heavy or super-heavy nuclei are neutron deficient due to the mechanism of their production - fusion-evaporation reactions. Two decay modes - β+ or electron capture (EC) decay are available where the latter is usually favored due to its larger Q value. With its Q values ranging up to several MeV, the EC decay can provide crucial information on the Nilsson configurations and energies of the states populated in the daughter nuclei, which cannot be accessed otherwise (e.g., via α decay). The excitation energies of multi-quasiparticle states can be used to estimate the influence of the nucleon-nucleon interaction. However, until now, the study of EC decay in the transfermium region was represented by only a few cases - 253Md, 257Rf, 258Db, 255Md, and 256Md.
The first part of the talk will be dedicated to the previous results of the EC decay investigations in the transfermium region and the method for the production of heavy isotopes. In addition, the experimental setup and the detection technique based on the registration of the coincidences between characteristic X rays and conversion electrons (CE) will be introduced. In the second part of the talk, the results of the 253No, 254No, and 254Md EC decay study will be presented. These results were based on the data sets obtained in the four experiments performed at the velocity filter SHIP in GSI Darmstadt. The tentative decay schemes of the high-energy excited states in 253Md, 254Md, and 254Fm populated via EC decay will be proposed. In addition, their tentative Nilsson configurations based on the theoretical predictions will be discussed. Interestingly, an intense feeding of the high-energy states in 254Fm via EC decay of 254Md was observed, in contrast with the predicted population of the low-spin and low-energy states.