1,721,052 research outputs found
Close to the edge
No full textThe tin isotope Sn-100 is key to understanding nuclear stability, but little is known about its properties. Precision measurements of closely related indium isotopes have now pinned down its mass
Perturbative Approach to Effective Shell-Model Hamiltonians and Operators
No full textThis article presents an overview of the derivation of effective shell-model Hamiltonian and decay operators within the framework of many-body perturbation theory, and discusses the results of selected shell-model studies based on these operators. More precisely, we give technical details that non-experts will need in order to derive shell-model Hamiltonians and operators starting from realistic nuclear potentials, and provide some guidance for shell-model calculations where the single-particle energies, two-body matrix elements of the residual interaction, effective charges, and decay matrix elements are all obtained without resorting to empirical adjustments. We report results of studies of double-β decay of heavy-mass nuclei where the shell-model ingredients are derived from theory, so as to assess the reliability of such an approach to shell-model investigations. Attention will be also focused on aspects relating to the behavior of the perturbative expansion, knowledge of which is needed for establishing limits and applying this approach to nuclear structure calculations
Gamow-Teller decays: Probing nuclear structure and weak interactions
Full text linkWe describe the Gamow-Teller decays for nuclear systems outside the 40 Ca and 56 Ni closed cores in the framework of the realistic shell model, starting from a nuclear Hamiltonian and electroweak currents as consistently obtained by means of chiral perturbation theory. The effective shell-model Hamiltonians and decay operators are derived using many-body perturbation theory, allowing the role of both electroweak currents and many-body correlations to be taken into account as the origin of the problem of the quenching of the axial coupling constant g A
Forbidden β decays within the realistic shell model
No full textFor the first time, half-lives and energy spectra of forbidden β decays are calculated within the realistic shell model. Namely, we approach this issue starting from a realistic nucleon-nucleon potential and deriving effective Hamiltonians and decay operators. Our goal is to explore the sensitivity of the shape of calculated energy spectra to the renormalization of forbidden β-decay operators, an operation that allows to take into account those configurations that are not explicitly included in the chosen model space. The region that has been considered for this investigation are nuclei outside the Ni78 core, more precisely we have studied the second-forbidden β decays of Nb94 and Tc99, and fourth-forbidden β decays of Cd113 and In115, that are currently of a renewed experimental interest in terms of novel spectroscopic techniques. Our results evidence that the introduction of a renormalized β-decay operator leads to a marked improvement of the reproduction of experimental half-lives. As regards the spectra of both second-forbidden and fourth-forbidden decays, we have found that their calculated shapes are in good agreement with the observed ones, even if scarcely responsive to the renormalization of the decay operator. We carry out also a detailed inspection of the different components of the calculated spectra for a deeper insight about their role in reproducing the experimental shapes
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