The pygmy dipole resonance and photon strength function in stable and unstable Ni and Sn isotopes are calculated within the microscopic self-consistent version of the extended theory of finite Fermi systems, which, in addition to the standard quasiparticle random-phase approximation approach, includes phonon coupling effects. The Skyrme force SLy4 is used. A pygmy dipole resonance in 72 Ni is predicted at the mean energy of 12.4 MeV exhausting 25.7% of the total energy-weighted sum rule. The microscopically obtained photon E1 strength functions are compared with available experimental data and used to calculate nuclear reaction properties. Average radiative widths and radiative neutron capture cross sections have been calculated taking phonon coupling into account as well as uncertainties caused by various microscopic level density models. In all three quantities considered, the contribution of phonon coupling turned out to be significant and is found necessary to explain available experimental data.

Neutron-capture reactions on very neutron-rich nuclei are essential for heavy-element nucleosynthesis through the rapid neutron-capture process, now shown to take place in neutron-star merger events. For these exotic nuclei, radiative neutron capture is extremely sensitive to their γ-emission probability at very low γ energies. In this work, we present measurements of the γ-decay strength of 70 Ni over the wide range 1.3 ≤ E γ ≤ 8 MeV. A significant enhancement is found in the γ-decay strength for transitions with E γ < 3 MeV. At present, this is the most neutron-rich nucleus displaying this feature, proving that this phenomenon is not restricted to stable nuclei. We have performed E1-strength calculations within the quasiparticle time-blocking approximation, which describe our data above E γ 5 MeV very well. Moreover, large-scale shell-model calculations indicate an M1 nature of the low-energy γ strength. This turns out to be remarkably robust with respect to the choice of interaction, truncation and model space, and we predict its presence in the whole isotopic chain, in particular the neutron-rich 72,74,76 Ni.

Phonon coupling (PC) corrections to magnetic moments of odd neighbors of magic and semimagic nuclei are analyzed within the self-consistent Theory of Finite Fermi Systems (TFFS) based on the Energy Density Functional by Fayans et al. The perturbation theory in g 2 L is used where gL is the phonon-particle coupling vertex. A model is developed with separating non-regular PC contributions, the rest is supposed to be regular and included into the standard TFFS parameters. An ansatz is proposed to take into account the so-called tadpole term which ensures the total angular momentum conservation with g 2 L accuracy. An approximate method is suggested to take into account higher order terms in g 2 L . Calculations are carried out for four odd-proton chains, the odd Tl, Bi, In and Sb ones. Different PC corrections strongly cancel each other. In the result, the total PC correction to the magnetic moment in magic nuclei is, as a rule, negligible. In non-magic nuclei considered it is noticeable and, with only one exception, negative. On average it is of the order of −(0.1 ÷ 0.5) µN and improves the agreement of the theory with the data. Simultaneously we calculated the gyromagnetic ratios g ph L of all low-lying phonons in 208 Pb. For the 3 − 1 state it is rather close to the Bohr-Mottelson model prediction whereas for other L-phonons, two 5 − and six positive parity states, the difference from the Bohr-Mottelson values is significant.

Problems that are associated with the description of radiative processes in low-energy physics for nuclear data and which can be solved within modern microscopic theory of the nucleus are discussed. This discussion concerns recent results in the theory of the pygmy dipole resonance and of the radiative strength function and the status of the Axel-Brink hypothesis. It is confirmed that coupling to phonon degrees of freedom must be taken into account in order to explain this resonance and the radiative strength function. By using the self-consistent generalized theory of finite Fermi systems, in which this coupling is taken into account, the pygmy dipole resonance is calculated for the 68 Ni and 116 Sn nuclei, and agreement with recent experimental data is obtained for the mean energy and for a 5% exhaustion of the sum rule for 68 Ni. For the example of the 68 Ni and 116 Sn nuclei, the E1 radiative strength functions are calculated for the first time with allowance for coupling to phonons, and the microscopic cross sections for total E1 photoabsorption that were obtained within the self-consistent generalized theory of finite Fermi systems are employed in these calculations.

Abstract. Ground state quadrupole moments of odd-odd near-double-magic nuclei are calculated in the approximation of non-interacting odd neutron and odd proton. Under such a simple approximation the problem is reduced to the calculations of quadrupole moments of corresponding odd-even nuclei. These calculations are performed within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. with the known DF3-a parameters. A reasonable agreement with the available experimental data is obtained for odd-odd nuclei and odd near-magic nuclei investigated. The self-consistent approach under consideration allowed us to predict the unknown quadrupole moments of odd-even and odd-odd nuclei near the double-magic 56,78 Ni, 100,132 Sn nuclides.