Self-consistent methods for the structure of heavy and superheavy nuclei are reviewed. The construction and application of energy-density functionals are discussed. The relationship between the ...self-consistent methods and microscopic-macroscopic approaches is considered on the mean-field level. The extraction of single-particle potentials from the energy-density functional is described. The isotopic dependence of nucleon distributions and its influence on the nucleus–nucleus interaction is analyzed. As a new additional condition we introduce that the energy-density functional must describe the heights of the Coulomb barriers in nucleus–nucleus interaction potentials, thus imposing constraints on the properties of the functional at low matter densities. The self-consistent methods are applied to describe the quasiparticle structure, cluster radioactivity, and fission of the heaviest nuclei. These methods are used to predict the probabilities of
β
-delayed multi-neutron emission and half-lives of
β
-decays and electron captures in heavy and superheavy nuclei. The predicted properties of superheavy nuclei are used to estimate the production cross-sections of superheavy nuclei in complete fusion reactions.
Compton scattering off the proton in the third resonance region is analyzed for the first time, owing to the full combined analysis of pion- and photo-induced reactions in a coupled-channel effective ...Lagrangian model with K-matrix approximation. Two isospin I=3/2 resonances D33(1700) and F35(1930) are found to be essential in the range of 1.6–1.8 GeV. The recent beam asymmetry data of Compton scattering from the GRAAL facility are used to determine the helicity couplings of these resonances, and strong constraints are coming also from πN and KΣ photoproduction data. The possible spin and parity of new narrow resonances is discussed.
For fusion reactions of astrophysical interest, the existence of a maximum of S-factor is revealed within the extended quantum diffusion approach. The available experimental data are well described. ...The reason and consequences of the existence of the S-factor maximum are explained. An universal formula for the position of the maximum is proposed.
We investigate for the first time the influence of hyperon–nucleon (YN) interaction models on the strangeness dynamics of antiproton–nucleus and Ξ–nucleus interactions. Of particular interest is the ...formation of bound multi-strangeness hypermatter in reactions relevant for P¯ANDA. The main features of two well-established microscopic approaches for YN-scattering are first discussed and their results are then analyzed such that they can be applied in transport-theoretical simulations. The transport calculations for reactions induced by antiproton beams on a primary target including also the secondary cascade beams on a secondary target show a strong sensitivity on the underlying YN-interaction. In particular, we predict the formation of Ξ-hypernuclei with an observable sensitivity on the underlying ΞN-interaction. We conclude the importance of our studies for the forthcoming research plans at FAIR.
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The article describes the main achievements of the NUMEN project together with an updated and detailed overview of the related R&D activities and theoretical developments. NUMEN proposes an ...innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the fact that the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave functions in the two types of processes and the formal similarity of the transition operators. First experimental results obtained at the INFN-LNS laboratory for the
40
Ca(
18
O,
18
Ne)
40
Ar reaction at 270MeV give an encouraging indication on the capability of the proposed technique to access relevant quantitative information. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer. The former is used for the acceleration of the required high resolution and low emittance heavy-ion beams and the latter is the large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the experimental resolution and sensitivity required for the accurate measurement of the DCE cross sections at forward angles. However, the tiny values of such cross sections and the resolution requirements demand beam intensities much larger than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities in this perspective is part of the NUMEN project and will be discussed in the article.
The electric quadrupole response is investigated theoretically by HFB and QPM calculations along the Sn isotopic chain with special emphasis on excitations above the first collective state and below ...the particle threshold. Depending on the asymmetry, additional quadrupole strength clustering as a group of states similar to the known Pygmy Dipole Resonance is found. The spectral distributions, electric quadrupole response functions and transition densities of low-energy quadrupole states show special features being compatible with oscillations of neutron or proton skins against the nuclear core.
The total and angular differential cross sections of the coherent process p¯+AZ→ΛA(Z−1)+Λ¯ are evaluated at the beam momenta 1.5÷20 GeV/c within the meson exchange model with bound proton and ...Λ-hyperon wave functions. It is shown that the shape of the beam momentum dependence of the hypernucleus production cross sections with various discrete Λ states is strongly sensitive to the presence of the scalar κ-meson exchange in the p¯p→Λ¯Λ amplitude. This can be used as a clean test of the exchange by scalar πK correlation in coherent p¯A reactions.
The quantum diffusion approach is extended to low-energy fusion (capture) reactions of light- and medium-mass nuclei. The dependence of the friction parameter on bombarding energy is taken into ...account. A simple analytic expression is obtained for the capture probability at extreme sub-barrier energies. The calculated cross-sections are in good agreement with the experimental data. The fusion excitation functions calculated within the quantum diffusion and WKB approaches are compared and presented in the astrophysical
S
-factor representation.
During the last decade, a theoretical method based on the energy–density functional theory and quasiparticle–phonon model, including up to three-phonon configurations was developed. The main ...advantages of themethod are that it incorporates a self-consistentmean-field and multi-configuration mixing which are found of crucial importance for systematic investigations of nuclear low-energy excitations, pygmy and giant resonances in an unified way. In particular, the theoretical approach has been proven to be very successful in predictions of new modes of excitations, namely pygmy quadrupole resonance which is also lately experimentally observed. Recently, our microscopically obtained dipole strength functions are implemented in predictions of nucleon-capture reaction rates of astrophysical importance. A comparison to available experimental data is discussed.
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