Isomeric yield ratios (IRs) of the fission products 130,132Sb, 131,133Te, 134,136I, 135Xe, and 138Cs were measured in the photofission of 232Th using bremsstrahlung end-point energies of 14 and 16 MeV. The experiments were performed at the 20 MeV ELBE electron linac (Helmholtz-Zentrum Dresden-Rossendorf), employing an off-line γ-ray spectrometric technique. From the measured IR values, the average root-mean-square angular momenta (JRMS) of the primary fragments were deduced using a spin-dependent statistical model analysis. The results demonstrate that JRMS values of fission fragments with a spherical N = 82 shell are significantly lower than those for fragments without a closed neutron shell. Furthermore, the JRMS of odd-Z fission products were found to be higher than those of adjacent even-Z products, suggesting a distinct single particle effect. These findings highlight the significant influence of nuclear structure on the fission process. A comparison with literature data at different energies suggests that the excitation energy of the compound nucleus has a negligible effect on the fragment angular momentum within the studied energy range.
We perform large-scale shell-model (SM) calculations of the β ^- -decay properties of neutron-rich nuclei with 30 ≤ Z ≤ 35 and 42 ≤ N ≤ 50 , employing different effective Hamiltonians within the f_5/2pg_9/2 model space. The calculations include half-lives, excitation energies, log ft values, summed B(GT) strengths, Q values, and branching ratios. A quenched axial-vector coupling, with a quenching factor of q = 0.71 derived from our earlier study in the same model space (Surender et al., Eur. Phys. J. A 61, 265 (2025)), is adopted and validated through Gamow–Teller matrix elements. Our results highlight the sensitivity of β ^- -decay observables to the choice of effective interaction within this model space. A comprehensive SM study of the β ^- -decay properties of nuclei in this region is presented here for the first time. Although the adopted model space is constrained by the omission of the f_7/2 and g_7/2 spin-orbit partner orbitals, the overall agreement with experimental data is satisfactory. Furthermore, Gamow–Teller strength distributions are systematically investigated by folding the discrete strengths with a 500 keV Lorentzian width.
This report summarizes the presentations and discussions during the ISO-BREAK 25 Workshop “Isospin symmetry violation: kaons and beyond”, which was held at Jan Kochanowski University in Kielce on October 23–25, 2025. We address the current status of the isospin-symmetry breaking discovered by NA61/SHINE in nucleus–nucleus collisions at the CERN SPS, its confirmation by other experiments and studies in e^++e^- and deep inelastic scattering. In addition, we discuss the theoretical status as well as we outline experimental and theoretical priorities towards understanding this currently unexplained phenomenon.
A machine learning ensemble model is constructed, comprising twenty stacked Bayesian Neural Networks and an XGBoost model. The physics-informed ensemble model enhances the prediction accuracy of nuclear binding energies, achieving a training accuracy of 46 keV and an overall accuracy of 60 keV for the data of AME2020. The testing accuracy of 97 keV crosses the 100 keV threshold required for nuclear astrophysical r-processes. Extrapolation performance is further validated on nuclei first newly measured after AME2020, yielding an accuracy of 175 keV. An Explanation–Causal Analysis–Threshold multi-scale analysis framework is employed to enhance model interpretability. The proposed approach, with its superior ability to both interpret and extrapolate, can be extended to other research fields.
The Generalized Variable-Moment-of-Inertia (GVMI) model, based on a nonlinear phenomenological rotational energy expression, is applied to investigate the negative-parity Δ I=2 Antimagnetic Rotation (AMR) bands in ^105Cd and ^101Pd nuclei. The model provides a satisfactory description of the observed excitation energies and reproduces the corresponding trend of the rotational frequency ħω . The semiclassical geometrical interpretation of the angular-momentum composition of the band is based on the gradual alignment of the relevant angular momentum vectors of proton-holes toward the neutron angular-momentum vector. This phenomenological description is consistent with the characteristic closing of the twin shears in AMR. The resulting evolution of the shears geometry is further used to examine the observed decrease of the electric quadrupole transition probabilities B(E2) with increasing spin. Thus, the GVMI approach offers a simple and transparent phenomenological framework for correlating the rotational energies, rotational frequencies, angular-momentum geometry, and B(E2) systematics of the band. Complementary microscopic insight is also provided by Cranked Shell Model (CSM) calculations, which include pairing correlations, for both ^105Cd and ^101Pd spectra with appropriate configurations before and after the backbending. The CSM results are found to be consistent with the observed rotational behavior associated with the AMR band. The comparison between the phenomenological GVMI analysis and the CSM results indicates that the simple GVMI parametrization captures important empirical features of the observed band while providing a complementary geometrical interpretation of its angular-momentum evolution. The present study therefore does not aim to replace microscopic descriptions of AMR, but demonstrates the usefulness of the GVMI model as a phenomenological tool for obtaining first-order structural information on such rotational bands.
