Three-body forces in carbon and oxygen nuclei

To test the predictive power of ab initio nuclear structure models, the lifetime of the second 2+ state in neutron-rich 20O, τ(22+)=150(-30,+80)fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens to hundreds femtosecond range by analyzing the Doppler-shifted gamma-transition line shapes of nuclei measured by  AGATA+PARIS+VAMOS setup. The experimental lifetimes agree with predictions of ab initio calculations using  two- and three-nucleon interactions for 20O and 16C. The present measurement shows the power of observables provided by electromagnetic transitions, determined with high-precision gamma spectroscopy, in assessing the quality of first-principles nuclear structure calculations.

M.Ciemała, (B.Fornal, A.Maj, P.Bednarczyk, N.Cieplicka-Orynczak, J.Grębosz, Ł.W.Iskra, M.Kicinska-Habior, M.Kmiecik, M.Lewitowicz, K.Mazurek, M.Matejska-Minda, P.Napiorkowski, M.Rejmund, B.Wasilewska, M.Zieblinski) et al.

Testing ab initio nuclear structure in neutron-rich nuclei: Lifetime measurements of second 2+ state in 16C and 20O

Physical Review C 101, 021303(R) (2020)
https://doi.org/10.1103/PhysRevC.101.021303

News in the theory of nuclear fission

One of the key observables of nuclear fission is fragment mass distribution. Theoretical description of the potential energy surface and inertia parameters allows predicting fragment mass distributions of each particular nuclide. We have investigated 96 isotopes of the elements from Pt (Z = 78) do Ra (Z = 88). Calculations were performed in the three-dimensional collective model based on the energies from the macroscopic-microscopic model with effective Fourier parametrization of nuclear shape. Experimental data are well reproduced when the neck rupture probability depends on the neck thickness.

Krzysztof Pomorski, Artur Dobrowolski, Rui Han, Bożena Nerlo-Pomorska, Michał Warda, Zhigang Xiao, Yongjing Chen, Lilie Liu, and Jun-Long Tian

Mass yields of fission fragments of Pt to Ra isotopes

Physical Review C 101, 064602 (2020)
https://doi.org/10.1103/PhysRevC.101.064602

Superdeformation can be triaxial

Experiments on superdeformed light nuclei were based on very careful observation and detailed analysis of the gamma radiation emitted by the nucleus of calcium 42Ca, caused to spin as a result of a collision with a target constructed of lead 208Pb or gold 197Au. The measurements were carried out at the Italian INFN Laboratori Nazionali di Legnaro (LNL), and they were used in the AGATA gamma radiation detector. This detector, the most advanced of the gamma-ray Germanium detectors currently in use, is the product of international cooperation and is characterized by an extremely high power of resolution. The experiment concerning superdeformation of the nuclei of calcium was the first one using this sophisticated device. The discovery of triaxial superdeformation in 42Ca will help physicists to better understand the phenomena in atomic nuclei.

Cooperation between the centres of Krakow and Warsaw is done within the consortium of the National Cyclotron Laboratory.

K.Hadyńska-Klęk, (P.J.Napiorkowski, M.Zielińska, J.Srebrny, A.Maj, M.Kicińska-Habior, P.Bednarczyk, M.Ciemała, A.Czermak, B.Dulny, B.Fornal, J.Grebosz, J.Iwanicki, G.Jaworski, M.Kmiecik, D.Karpiński, M.Kisieliński, M.Komorowska, M.Kowalczyk, M.Krzysiek, K.Mazurek, W.Meczyński, S.Myalski, M.Palacz, L.Próchniak, K.Rusek, J.Styczeń, B.Wasilewska, K.Wrzosek-Lipska, M.Ziebliński) et al.

Quadrupole collectivity in Ca 42 from low-energy Coulomb excitation with AGATA

Physical Review C 97, 024326 (2018)
DOI: 10.1103/PhysRevC.97.024326

K.Hadyńska-Klęk, (P.J.Napiorkowski, M.Zielińska, J.Srebrny, A.Maj, M.Kicińska-Habior, P.Bednarczyk, M.Ciemała, A.Czermak, B.Dulny, B.Fornal, J.Grebosz, J.Iwanicki, G.Jaworski, M.Kmiecik, D.Karpiński, M.Kisieliński, M.Komorowska, M.Kowalczyk, M.Krzysiek, K.Mazurek, W.Meczyński, S.Myalski, M.Palacz, L.Próchniak, K.Rusek, J.Styczeń, B.Wasilewska, K.Wrzosek-Lipska, M.Ziebliński) et al.

Superdeformed and Triaxial States in 42Ca

Physical Review Letters 117, 062501 (2016);
DOI: 10.1103/PhysRevLett.117.062501

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