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

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