Fano-resonances are investigated as a new continuum excitation mode in exotic nuclei. By theoretical model calculations we show that the coupling of a single particle elastic channel to closed ...core-excited channels leads to sharp resonances in the low-energy continuum. A signature for such bound states embedded in the continuum (BSEC) are characteristic interference effects leading to asymmetric line shapes. Following the quasiparticle-core coupling model we consider the coupling of 1-QP (one-quasiparticle) and 3-QP components and find a number of long-living resonance structures close to the particle threshold. Results for 15C are compared with experimental data, showing that the experimentally observed spectral distribution and the interference pattern are in qualitative agreement with a BSEC interpretation.
The electric quadrupole response in 112,114Sn isotopes is investigated by energy-density functional (EDF) and three-phonon quasiparticle-phonon model (QPM) theory with special emphasis on electric ...quadrupole excitations located above the first collective 2+ state and below 5 MeV. Additional quadrupole strength clustering as a sequence of states similar to the recently observed pygmy quadrupole resonance in 124Sn is found. The spectral distributions and transition densities of these 2+ states show special features being compatible with oscillations of a neutron skin against the isospin-symmetric nuclear core. Furthermore, two (p, p′γ) Doppler-shift attenuation (DSA) coincidence experiments were performed at the SONIC@HORUS setup. 2+ states with excitation energies up to 4.2 MeV were populated in 112,114Sn. Lifetimes and branching ratios were measured allowing for the determination of E2 transition strengths to the ground state. A stringent comparison of the new data to EDF+QPM theory in 112Sn and 114Sn isotopes hints at the occurrence of a low-energy quadrupole mode of unique character which could be interpreted as pygmy quadrupole resonance.
An innovative technique to access the nuclear matrix elements entering the expression of the life time of the double beta decay by relevant cross section measurements of double charge exchange ...reactions is proposed. A key aspect of the project is the use of the MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the LNS K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams, already in operation at INFN Laboratory Nazionali del Sud in Catania (Italy). However, a major upgrade is foreseen for the INFN-LNS research infrastructure to cope with beam currents as high as several ppA required by the project.
The nucleon density profiles of spherical nuclei are calculated within the self-consistent HFB approach based on the non-covariant energy density functional. For the reactions with light nuclei, the ...nucleus–nucleus interaction potentials are calculated in the double-folding form with these nucleon densities. The characteristics of the Coulomb barriers obtained are in good agreement with those required to describe the sub-barrier complete fusion. The energy density functional used provides a reliable basis to calculate the nucleus–nucleus potential in the reactions of astrophysical interest. A simple parametrization for the nuclear part of the nucleus–nucleus interaction is proposed to estimate the height, position, and curvature of the Coulomb barrier.
The comparative analysis of the hot fusion reactions Ti50+247−249Bk and V51+246−248Cm for synthesis of element 119 is made with the dinuclear system model and the prediction of nuclear properties of ...the microscopic–macroscopic approach, where the closed proton shell at Z≥120 is expected. The quasiparticle structures of nuclei in the α-decay chain of 295119 and a possible spread of alpha energies are studied. The calculated values of Qα are compared with available experimental data. The termination of the α-decay chain of 295119 is revealed.
Dynamical correlations in asymmetric infinite nuclear matter are investigated in a transport theoretical approach. Self-energies due to short range correlations and their influence on the nucleon ...spectral functions are described in an approach accounting for a realistic treatment of mean-field dynamics and a self-consistently derived quasiparticle interaction. Landau–Migdal theory is used to derived the short range interaction from a phenomenological Skyrme energy density functional. The spectral functions in asymmetric nuclear matter are found to follow in their gross features closely the patterns observed previously in symmetric nuclear matter. An interesting sensitivity of dynamical self-energies and spectral functions on the momentum structure of the underlying interactions is found.
We review the status and prospects of heavy-ion double charge exchange (HI-DCE) reactions. Their important role for nuclear reaction, nuclear structure and double beta-decay investigations is ...outlined. From the experimental side the characteristically tiny cross sections for these processes and the high background generated by other more probable competing reactions is the main challenge, which has hindered HI-DCE spectroscopy until recent years. Modern magnetic spectrometers have proven to possess the right requisites to overcome past limitations, fostering the present and future development of the field. From the theory side, the description of the measured HI-DCE cross sections poses manifold challenges. Dealing with processes which involve composite nuclei, HI-DCE reactions can, in principle, proceed through several alternative paths. These, in turn, correspond to different reaction mechanisms probing competing aspects of nuclear structure, from mean field to various classes of nucleon–nucleon interactions and correlations. A powerful way to scrutinize the nuclear response to HI-DCE is to consistently link it to the information extracted from the competing direct reactions. Indeed, these complementary studies are mandatory in order to minimize the systematic errors in the data analyses and build a many-facets and parameter-free representation of the systems under study.
Break-up of secondary Li-11 ion beams (280 MeV/nucleon) on C and Pb targets into Li-9 and neutrons is studied experimentally. Cross sections and neutron multiplicity distributions are obtained, ...characterizing different reaction mechanisms. Invariant-mass spectroscopy for Li-11 and Li-10 is performed. The E1 strength distribution, deduced from electromagnetic excitation of Li-11 up to an excitation energy of 4 MeV comprises similar to 8% of the Thomas-Reiche-Kuhn energy-weighted sumrule strength. Two low-lying resonance-like structures are observed for Li-10 at decay energies of 0.21(5) and 0.62(10) MeV, the former one carrying 26(10)% of the strength and likely to be associated with an s-wave neutron decay. A strong di-neutron correlation in Li-11 can be discarded. Calculations in a quasi-particle RPA approach are compared with the experimental results for Li-10 and Li-11. (C) 1997 Elsevier Science B.V.
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