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Self-consistent calculations of potential surfaces, quadrupole moments, and charge radii of the mercury isotopes Hg are calculated within the approach based on the Fayans energy-density functional. The existence of weakly oblate and strongly prolate isomeric states is shown. The charge radii are predicted to a typical precision of 0.01 fm for all isotopes, with the exception of three particular cases of Hg. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on the influence of the conditions of volume electric arc surfacing on the geometric accuracy of "cube" type objects with dimensions of 20 × 20 × 20 mm made of 09Mn2Si and 06Cr19Ni9Ti steel fillers. It has been found that the actual length and width dimensions of the samples surfaced with 09Mn2Si steel generally are exceeded and the dimensions in height are smaller than the specified dimensions of the model. This may be due to the melt spreading over the substrate during the formation of the first layers. The optimal surfacing conditions for cube type objects made of 09Mn2Si steel have been defined. When surfacing the samples of 06Cr19Ni9Ti steel, spreading does not occur; however, all actual dimensions are smaller than the specified ones. This might be caused by shrinkage processes that proceed in the deposited layers during their solidification. The most optimal mode for samples made of 06Cr19Ni9Ti steel is the mode in which the reduction in length and width was no more than 2.5%, and that in height was 13.5%. Studies on the influence of the welding arc voltage and the grade of the filler material on the width of the deposited track has confirmed the tendency of 09Mn2Si steel to spread over the substrate in the entire voltage range studied (11–19 V). The microstructure of the deposited samples has been investigated. Tensile tests of the deposited samples at room temperature have shown that the samples have a set of acceptable mechanical properties that exceed the reference values. This is a proof that the deposition process occurs at a high level of quality without formation of incomplete fusion and porosity areas. [ABSTRACT FROM AUTHOR]

The relation between the broken rotational symmetry of a system and the topology of its Fermi surface is studied for the two-dimensional system with the quasiparticle interaction f(p, p') having a sharp peak at |p − p'| = q0. It is shown that, in the case of attraction and q0 = 2pF the first instability manifesting itself with the growth of the interaction strength is the Pomeranchuk instability. This instability appearing in the L = 2 channel gives rise to a second order phase transition to a nematic phase. The Monte Carlo calculations demonstrate that this transition is followed by a sequence of the first and second order phase transitions corresponding to the changes in the symmetry and topology of the Fermi surface. In the case of repulsion and small values of q0, the first transition is a topological transition to a state with the spontaneously broken rotational symmetry, namely, corresponding to the nucleation of L ≃ π(pF/q0 − 1) small hole pockets at the distance pF − q0 from the center and the deformation of the outer Fermi surface with the characteristic multipole number equal to L. At q0 → 0, when the model under study transforms to the two-dimensional Nozières model, the multipole number characterizing the spontaneous deformation is L → ∞, whereas the infinitely folded Fermi curve acquires the Hausdorff dimension D = 2 which corresponds to the state with the fermion condensate. [ABSTRACT FROM AUTHOR]

model has been proposed in which the ab initio effective pairing interaction in atomic nuclei is supplemented by a small phenomenological term containing one parameter universal for all intermediate-mass and heavy nuclei. The neutron and proton pairing gaps have been calculated for several chains of semimagic nuclei; these calculations demonstrate the applicability of this model. [ABSTRACT FROM AUTHOR]

The single-particle spectrum and momentum distribution of quasiparticles in a cold dense quark-gluon plasma are calculated within the Fermi liquid approach. It is shown that this system does not behave as a standard Fermi liquid: at zero temperature, the single-particle spectrum has a plateau at the Fermi surface, while the Fermi surface itself has a nonzero volume in momentum space. [ABSTRACT FROM AUTHOR]

Recent results obtained by solving the ab initio equation for the pairing gap in a slab of nuclear matter are reviewed. They conclusively prove a surface nature of nucleon pairing in nuclei. First, the effective pairing interaction in the vicinity of the slab surface makes a dominant contribution to the gap. Second, there is a sizable surface enhancement of the pairing gap Δ( X) itself. Finally, an analysis of spatial correlation features of the anomalous density matrix shows that the local correlation length at the slab surface is very small, about 1.5 fm, but, in the interior of the slab, it is rather large, about the slab thickness. These results are in qualitative agreement with those obtained recently by Pillet and his coauthors for spherical nuclei by using the phenomenological Gogny force. An increase in the concentration of Cooper pairs at the surface of nuclei was yet another result of their study, and our present analysis confirms this indirectly. [ABSTRACT FROM AUTHOR]

The effective pairing interaction corresponding to the Argonne nucleon-nucleon potential v18 is found within the local potential approximation for several values of the boundary energy E 0 that specifies the model subspace S 0. A detailed comparison with the analogous effective interaction calculated previously for the Paris nucleon-nucleon potential is performed. It is shown that the effective interactions obtained for the two different nucleon-nucleon potentials at the same value of E 0 are very close to each other. In the case of the Paris potential, a very wide subspace S′ complementary to S 0 was required in calculating the effective interaction (the corresponding cutoff momentum being k max = 160−180 fm−1), whereas a much narrower subspace S′ corresponding to k max = 10−12 fm−1 could be used in the case of the Argonne potential. [ABSTRACT FROM AUTHOR]

The effective pairing interaction corresponding to the Argonne nucleon-nucleon potential v18 is found within the local potential approximation for several values of the boundary energy E 0 that specifies the model subspace S 0. A detailed comparison with the analogous effective interaction calculated previously for the Paris nucleon-nucleon potential is performed. It is shown that the effective interactions obtained for the two different nucleon-nucleon potentials at the same value of E 0 are very close to each other. In the case of the Paris potential, a very wide subspace S′ complementary to S 0 was required in calculating the effective interaction (the corresponding cutoff momentum being k max = 160−180 fm−1), whereas a much narrower subspace S′ corresponding to k max = 10−12 fm−1 could be used in the case of the Argonne potential. [ABSTRACT FROM AUTHOR]

The equation for the pairing gap Δ in a slab of nuclear matter governed by the Paris nucleon-nucleon potential is solved for various values of the chemical potential µ in the range from −8 MeV, which corresponds to stable nuclei, to −0.1 MeV, which corresponds to nuclei in the vicinity of the nucleon drip line. The slab is placed in a one-dimensional Woods-Saxon potential whose parameters are set to values typical of nuclei. Two models are considered. In the first, the potential-well depth is fixed at U 0 = −50 MeV, the density within the slab growing as |µ| is reduced. In the second model, the density is fixed at the center of the slab, | U 0| decreasing as |µ| is reduced. The behavior of the gap Δ as a function of µ is model-dependent. In the first model, Δ decreases with decreasing |µ|, while, in the second, it increases. At the same time, the effect of the surface enhancement of Δ becomes more pronounced with decreasing |µ| in both models. [ABSTRACT FROM AUTHOR]