[en] We investigate the role the interweaving of surface vibrations and nucleon motion has on Cooper pair formation in spherical superfluid nuclei. This is done solving self-consistently the Dyson equation with the normal and anomalous density Green functions. Effective and realistic nucleon-nucleon interactions are used. It is found, that the pairing gap receives about equal contributions from the bare and from the induced interaction. It is furthermore found that the self-energy processes reduce the pairing gap by about 20%. The extreme cases of the ¹¹Li and ¹²Be nuclei are also discussed

[en] After the April 1986 nuclear reactor accident at Chernobyl in the Union of Soviet Socialist Republics, samples of human placenta and breast milk were tested for 1 year to determine the levels of radioactivity. The radionuclide iodine 131 was never beyond the detection limit of our gamma detector for both matrices. As to cesium isotopes 134 and 137, the highest levels detected in breast milk (6 Bq.L-1) and placenta (15.8 Bq.kg-1) were recorded in March 1987. Study data for breast milk and placenta are in agreement with the values calculated by means of double-compartment food-milk and food-placenta models. With regard to placental content, the cesium contribution to the average dose during the year after the Chernobyl accident was calculated to be 40 to 60 microSv

[en] We calculate, for the first time, the state-dependent pairing gap of a finite nucleus (¹²⁰Sn) diagonalizing the bare nucleon-nucleon potential (Argonne v₁₄) in a Hartree-Fock basis (with effective k-mass m_k ∼0.7 m), 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. (orig.)

[en] The role the exchange of phonons between pairs of fermions moving in time reversal states lying close to the Fermi energy on the superfluidity and on the superconductivity of atomic nuclei and fullerenes respectively is discussed in terms of mean field theory and of ab-initio calculations. (orig.)

[en] The exchange of low-lying collective vibrations between pairs of nucleons moving in time reversal states close to the Fermi energy provides a conspicuous contribution to the nuclear pairing interaction, which accounts for 30-50% of the pairing gap in the case of nuclei along the stability valley, and to essentially all of the pairing correlations of the most loosely bound nucleons in the case of halo nuclei. (orig.)

[en] The effective pairing interaction induced by the exchange of phonons between pairs of nucleons moving in time-reversal states close to the Fermi energy in deformed nuclei modifies in a sizeable manner the superfluid properties of these systems, accounting for about half of the pairing gap

[en] Medium polarization effects induce an effective pairing interaction between nucleons which renormalize the nucleon-nucleon bare potential. We assess the importance of these renormalization processes concerning pairing correlations in both exotic nuclei as well as nuclei lying along the stability valley

[en] The three-body description of two-neutron halo systems is extended to allow for core polarization taking into account the associated effects of mass-renormalization (single-particle motion) and induced interaction (density dependent pairing force) in terms of the particle-vibration coupling formalism. This formalism is applied to ¹⁰Li and ¹¹Li. Theory reproduces most of the attractive features of Faddeev type calculations providing, in addition, an overall account of the experimental findings

[en] The coupling of single-particle motion and of vibrations in ₄¹¹Be produces dressed neutrons which spend only a fraction of the time in pure single-particle states, and which weighing differently from the bare neutrons lead to parity inversion. The interaction of the two least bound neutrons in the ground state of ₄¹²Be mediated by the v₁₄ Argonne nucleon-nucleon potential and by the exchange of surface vibrations of the core ¹⁰Be gives rise to a strongly correlated state, where the two valence neutrons are distributed over s²,p², and d² configurations, resulting in the breaking of the N=8 shell closure

[en] The induced pairing interaction arising from the exchange of low-lying collective surface vibrations among nucleons moving in time reversal state close to the Fermi energy is found to lead to values of the pairing gap which constitute a large fraction of those experimentally observed. (author)