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V. Yu. Ponomarev P. F. Bortignon R. A. Broglia V. V. Voronov 《Zeitschrift für Physik A Hadrons and Nuclei》1987,356(3):251-254
Damping width of the double giant dipole resonance of 136Xe excited in relativistic heavy ion collisions is calculated by diagonalizing a microscopic Hamiltonian in a basis containing one-, two- and three-phonon states. The coupling between these states is determined making use of the fermion structure of the phonons. The resulting width of the double giant dipole resonance is close to \(\left( {3_1^ + } \right)\) times the width of the single giant dipole resonance. 相似文献
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Particle-vibration coupling: Recent advances in microscopic calculations with the Skyrme Hamiltonian
In this contribution, we report some recent progress in our understanding of particle-vibration coupling (PVC) in nuclei. In particular, we first review the formal development that has allowed some of us to deduce the PVC equations within the Green’s functionmethod. Applications are then discussed, both in the case of single-particle states and giant resonances in magic nuclei. We also present a new model that extends the PVC ansatz and is meant to account for the complete low-lying spectra of odd nuclei. 相似文献
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Barranco F. Broglia R. A. Coló G. Gori G. Vigezzi E. Bortignon P. F. 《The European Physical Journal A - Hadrons and Nuclei》2004,21(1):57-60
We calculate, for the first time, the state-dependent pairing gap of a finite nucleus (120Sn) diagonalizing the bare nucleon-nucleon potential (Argonne v
14) in a Hartree-Fock basis (with effective k-mass
), within the framework of the generalized Bogoliubov-Valatin approximation including scattering states up to 800 MeV above the Fermi energy to achieve convergence. The resulting gap accounts for about half of the experimental gap. The combined effect of the bare nucleon-nucleon potential and of the induced pairing interaction arising from the exchange of low-lying surface vibrations between nucleons moving in time-reversal states close to the Fermi energy accounts for the experimental gap.Received: 3 November 2003, Published online: 6 July 2004PACS:
21.30.Fe Forces in hadronic systems and effective interactions - 21.60.Jz Hartree-Fock and random-phase approximations - 21.60.-n Nuclear structure models and methods - 27.60. + j
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The octupole response function for 208Pb, 120Sn, 90Zr and 40Ca, is calculated in the RPA. Of the order of 60–70% of the EWSR is found around an energy of 3?ω0, spread over an energy interval of ~ 15 MeV. About half of this strength (~ 30%) lies in a single peak. Based on the excitation of surface vibrations, the widths of these states are estimated within the framework of the nuclear field theory. They are found to be of the order of 6 MeV. The results seem to be consistent with recent data. 相似文献
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The damping widths of single-particle states and of giant resonances are estimated in spherical nuclei, based on the excitation of surface modes.A Skyrme III interaction with an effective mass consistent with that resulting from infinite nuclear matter calculations with “realistic” forces , was utilized. The single-particle basis needed to construct the unperturbed nuclear response function for each multipolarity was obtained, treating this force in the Hartree-Fock approximation. Diagonalizing a schematic interaction in this basis, the surface modes were calculated. They are used to dress the single-particle and single-hole states and to renormalize the vertex interaction, taking into account the proper energy dependence of the couplings.The essential new feature of the present calculation as compared to the calculations reported in ref.1) is that the energy dependence of the real and imaginary part of the self-energy is taken into account. This is done utilizing a strength function model.About 70 % of the damping widths arise from the coupling to specific intermediate states containing one low-lying collective surface vibration. The rest, from the coupling to many nonspecific states.Qualitative agreement is found with the experimental data for spherical nuclei throughout the mass table for both the single-particle states and the giant resonances. The model seems however to predict widths which are smaller than those experimentally observed. 相似文献
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F. Lucarelli N. Gelli P. Blasi M. Cinausero E. Fioretto G. Prete D. Fabris G. Nebbia G. Viesti E. M. Fiore L. Fiore V. Paticchio P. F. Bortignon 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):35-39
High-energyγ-rays from the32S+74Ge reaction at 210 MeV bombarding energy were measured in coincidence with light charged particles detected in a large area hodoscope. Experimental results show that energeticγ-rays in coincidence with light charged particles are essentially emitted in the compound nucleus decay. The parameters of the giant dipole resonance (GDR) have been extracted from alineshape analysis of the experimentalγ-ray spectrum. The derived values of mean energyE D, widthΓ and strengthS are in good agreement with results from previous experiments on Sn isotopes obtained by using different experimental techniques. 相似文献
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F. Barranco P.F. Bortignon R.A. Broglia G. Colò E. Vigezzi 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):385-392
If neutrons are progressively added to a normal nucleus, the Pauli principle forces them into states of higher momentum. When
the core becomes neutron saturated, the nucleus expels most of the wave function of the last neutrons outside to form a halo,
which, because of its large size, can have a lower momentum. It is an open question how nature stabilizes such a fragile system
and provides the glue needed to bind the halo neutrons to the core. Here, we show that this problem is similar to that of
the instability of the normal state of an electron system at zero temperature solved by Cooper, a solution which is at the
basis of BCS theory of superconductivity. By mimicking this approach using, aside from the bare nucleon-nucleon interaction,
the long wavelength vibrations of the nucleus 11Li, the paradigm of halo nuclei, as tailored glues of the least bound neutrons, we are able to obtain a unified and quantitative
picture of the observed properties of 11Li.
Received: 9 May 2001 / Accepted: 17 November 2001 相似文献
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