University of Jyväskylä

Dissertation: 18.12.2017 Discovery of the new isotopes 240Es and 236Bk and in-beam spectroscopic studies of 244Cf (Konki)

Start date: Dec 18, 2017 12:00 PM

End date: Dec 18, 2017 03:00 PM

Location: Ylistönrinne, FYS1

Joonas Konki picture: Janne Pakarinen
M.Sc. Joonas Konki defends his doctoral dissertation in Physics "Discovery of the new isotopes 240Es and 236Bk and in-beam spectroscopic studies of 244Cf". Opponent Professor Dirk Rudolph (Lund University) and custos Professor Paul Greenlees (University of Jyväskylä). The doctoral dissertation is held in English.


The hitherto unknown neutron-deficient nuclei 240Es and 236Bk were synthesised for the first time. The RITU gas-filled recoil separator and the GREAT spectrometer were employed in this decay spectroscopic study. The measured electron-capture delayed fission (ECDF) branches in both of the new isotopes complement the experimental data available in the heavier odd-odd Es and Bk isotopes. Furthermore, the ECDF branches are the largest that have ever been measured in the isotopes of these elements. In addition, an in-beam gamma-ray spectroscopic study of the neutron-deficient isotope 244Cf was performed in this work with the JUROGAMII germanium detector array coupled to the RITU and GREAT systems. The excited states in 244Cf were studied for the first time using the recoil-decay tagging method. The ground-state rotational band of 244Cf was measured up to a tentative spin and parity of 20+. The results were compared to the systematic behaviour of the heavy even-even N = 146 isotones as well as to theoretical calculations where available. Modern theoretical models and their predictive power in this region were challenged to reproduce the experimental results.

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Joonas Konki
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