BP2 achievements 2013-16: long-lived superheavy nuclei and the hyper deformation mystery

Cross-sections for production of superheavy nuclei planned to be synthesized soon have been predicted [1]. It has been shown that probability of production of even the heaviest nucleus in the nature composed of total 285 nucleons should be high enough.

The performed calculations for odd superheavy nuclei (only very few calculations for such nuclei are available in the literature) have yielded some basic properties of the nuclei, including their masses, deformations, energies of α-decays. Compatibility of the predictions with experimental data was excellent [2]. Only a few candidates for long-lived superheavy nuclei have been found among more than 1,000 tested nucleon systems [3]. New so far unknown mechanisms that forbid decays of such nuclei have been proposed with a suggestion that the mechanisms significantly increase stability of some of the nuclei.

Excellent IT infrastructure available in NCBJ helped to compute the currently most detailed in the world maps of potential energies. The maps were calculated using grids each composed of 50 million nodes. Deformations of nuclei undergoing decays were described in the full 8-dimensional space. Results of the work helped to explain the mystery of hyper deformation of the nuclei. For the first time it has been shown that the mysterious hyper deformation third minima are blurred if shapes of some suitable class (the so-called dipole variable) are taken into account. The minima are very shallow regardless of the used theoretical model. Thus a clear conflict between theory and experiment is evident. The results have been published in the recognized Physical Review C journal. Paper [4] has been distinguished by editors of the journal.

[1] Calculations of the cross sections for the synthesis of new 293–296118 isotopes in 249–252Cf(48Ca,xn) reactions, T. Cap, K. Siwek-Wilczyńska, M. Kowal, and J. Wilczyński, Phys. Rev. C 88, 037603 (2013)

[2] Qα values in superheavy nuclei from the deformed Woods-Saxon model, P. Jachimowicz, M. Kowal, and J. Skalski, Phys. Rev. C 89, 024304 (2014)

[3] Candidates for long-lived high-K ground states in superheavy nuclei P. Jachimowicz, M. Kowal, and J. Skalski, Phys. Rev. C 92, 044306, (2015)

[4] Eight-dimensional calculations of the third barrier in 232Th, P. Jachimowicz, M. Kowal, and J. Skalski, Phys. Rev. C 87, 044308 (2013)