Physics of Atomic Nuclei (PHYS ATOM NUCL+)

Publications in this journal

• Article: The double ionization of H$_2$ by fast electron impact: influence of the final state electron-electron correlation

  A.A. Gusev O. Chuluunbaatar, B. Joulakian
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  ABSTRACT: We have determined fully differential cross sections of the (e, 3e) double ionization of H_2 by employing correlated initial- and final-state wave functions. We have constructed for the description of the two slow ejected electrons a symmetrized product of a correlation function and two-center continuum wave functions, which fulfill the correct boundary conditions asymptotically up to the order O((kr)^{−2}). We have shown that the introduction of the correlated part of the final-state wave function improves the results on the (e, 3−1e) of H_2.
  Physics of Atomic Nuclei 02/2013; 76(2):121-125.
• Article: Spallation Reactions in Shock Waves at Supernova Explosions and Related Problems

  G. K. Ustinova
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  ABSTRACT: The isotopic anomalies of some extinct radionuclides testify to the outburst of a nearby supernova just before the collapse of the protosolar nebula, and to the fact that the supernova was Sn Ia, i.e. the carbon-detonation supernova. A key role of spallation reactions in the formation of isotopic anomalies in the primordial matter of the Solar System is revealed. It is conditioned by the diffusive acceleration of particles in the explosive shock waves, which leads to the amplification of rigidity of the energy spectrum of particles and its enrichment with heavier ions. As a consequence, the fluxes of nuclear-active particles above the thresholds of nuclear reactions increase, as well as the average cross sections weighted according to the spectrum of accelerated particles change, so that the production rates of isotopes change and the isotopic anomalies arise. The quantitative calculations of such isotopic anomalies of many elements are presented. It is well-grounded that the anomalous Xe-HL in meteoritic nanodiamonds was formed simultaneously with nanodiamonds themselves during the shock wave propagation at the Sn Ia explosion. The possible effects of shock wave fractionation of noble gases in the atmosphere of planets are considered. The origin of light `elements Li, Be and B in spallation reactions, predicted by Fowler in the middle of the last century, is argued. All the investigated isotopic anomalies give the evidence for the extremely high magneto- hydrodynamics conditions at the initial stage of free expansion of the explosive shock wave from SnIa, so that the maximum energy of accelerated particles could reach ~3 • 1015 eV, i.e. the energy region of the famous “knee” in the spectrum of cosmic rays. This information reaffirms the important role of the mechanism of the diffusive acceleration of particles by the explosive shock waves in the origin of cosmic rays. The phenomenon of Sn Ia, namely, the injection of its specific iron-enriched matter into the collapsing gas-dust protosolar nebula led inevitably to the heterogeneity of accretion, which was ignored in the existing condensation models of the origin of the Solar System. Meantime, the magneto-hydrodynamics metal-silicate separation in turbulent processes, e.g. in giant turbulent vortexes, naturally explains the earlier creation of metal centers of accretion and many other subtle features of formation of bodies of the Solar System. Some ways of integration of the condensation and magneto-hydrodynamics models are proposed.
  Physics of Atomic Nuclei 01/2013; 76(5):616–655.
• Article: Elastic and transition form factors of light pseudoscalar mesons from QCD sum rules

  Dmitri Melikhov, Irina Balakireva, Wolfgang Lucha
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  ABSTRACT: We revisit $F_\pi(Q^2)$ and $F_{P\gamma}(Q^2)$, $P=\pi,\eta,\eta'$, making use of the local-duality (LD) version of QCD sum rules. We give arguments, that the LD sum rule provides reliable predictions for these form factors at $Q^2 \ge 5-6$ GeV$^2$, the accuracy of the method increasing with $Q^2$ in this region. For the pion elastic form factor, the well-measured data at small $Q^2$ give a hint that the LD limit may be reached already at relatively low values of momentum transfers, $Q^2\approx 4-8$ GeV$^2$; we therefore conclude that large deviations from LD in the region $Q^2=20-50$ GeV$^2$ seem very unlikely. The data on the ($\eta,\eta')\to\gamma\gamma^*$ form factors meet the expectations from the LD model. However, the {\sc BaBar} results for the $\pi^0\to\gamma\gamma^*$ form factor imply a violation of LD growing with $Q^2$ even at $Q^2\approx 40$ GeV$^2$, at odds with the $\eta,\eta'$ case and with the general properties expected for the LD sum rule.
  Physics of Atomic Nuclei 01/2013; 76(3):326.
• Article: Investigation of Isomeric Ratios in High-Energy Reactions

  A. S. Danagulyan, G. H. Hovhannisyan, A. R. Balabekyan, N. A. Demekhina, V. G. Kalinnikov
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  ABSTRACT: Experimental data on the isomeric ratios of cross sections for products originating from the interaction of 12C ions (E12C = 26.4 GeV), protons (Ep = 3.65 GeV), and deuterons (Ed = 7.3 GeV) with targets enriched in the tin isotopes 112Sn, 118Sn, 120Sn, and 124Sn are presented. The dependence of the isomeric ratios on the interaction mechanism, projectile type and energy, and nuclear properties of the final-state nucleus are discussed. The dependence of the isomeric ratios on the degree of deformation of the product nucleus is also considered.
  Physics of Atomic Nuclei 01/2013; 76:349.
• Article: Field-theory methods in coagulation theory

  A. A. Lushnikov
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  ABSTRACT: Coagulating systems are systems of chaotically moving particles that collide and coalesce, producing daughter particles of mass equal to the sum of the masses involved in the respective collision event. The present article puts forth basic ideas underlying the application of methods of quantum-field theory to the theory of coagulating systems. Instead of the generally accepted treatment based on the use of a standard kinetic equation that describes the time evolution of concentrations of particles consisting of a preset number of identical objects (monomers in the following), one introduces the probability W(Q, t) to find the system in some state Q at an instant t for a specific rate of transitions between various states. Each state Q is characterized by a set of occupation numbers Q = {n 1, n 2, ..., n g , ...}, where n g is the total number of particles containing precisely g monomers. Thereupon, one introduces the generating functional Ψ for the probability W(Q, t). The time evolution of Ψ is described by an equation that is similar to the Schrödinger equation for a one-dimensional Bose field. This equation is solved exactly for transition rates proportional to the product of the masses of colliding particles. It is shown that, within a finite time interval, which is independent of the total mass of the entire system, a giant particle of mass about the mass of the entire system may appear in this system. The particle in question is unobservable in the thermodynamic limit, and this explains the well-known paradox of mass-concentration nonconservation in classical kinetic theory. The theory described in the present article is successfully applied in studying the time evolution of random graphs.
  Physics of Atomic Nuclei 05/2012; 74(8):1096-1106.
• Article: Neutrino masses, mixings, and FCNC’s in an S3 flavor symmetric extension of the standard model

  A. Mondragón, M. Mondragón, E. Peinado
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  ABSTRACT: By introducing threeHiggs fields that are SU(2) doublets and a flavor permutational symmetry, S 3, in the theory, we extend the concepts of flavor and generations to the Higgs sector and formulate a Minimal S 3-Invariant Extension of the Standard Model. The mass matrices of the neutrinos and charged leptons are re-parameterized in terms of their eigenvalues, then the neutrino mixing matrix, V PMNS, is computed and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of neutrinos and charged leptons are obtained in excellent agreement with the latest experimental data. We also compute the branching ratios of some selected flavor-changing neutral current (FCNC) processes, as well as the contribution of the exchange of neutral flavor-changing scalars to the anomaly of the magnetic moment of the muon, as functions of the masses of charged leptons and the neutral Higgs bosons. We find that the S 3 × Z 2 flavor symmetry and the strong mass hierarchy of the charged leptons strongly suppress the FCNC processes in the leptonic sector, well below the present experimental bounds by many orders of magnitude. The contribution of FCNC’s to the anomaly of the muon’s magnetic moment is small, but not negligible.
  Physics of Atomic Nuclei 05/2012; 74(7):1046-1054.
• Article: Cross sections for monitor reactions 27Al((p, x)24Na, 27Al(p, x)22Na, and 27Al(p, x)7Be at proton energies in the range 0.04–2.6 GeV

  Yu. E. Titarenko, S. P. Borovlev, M. A. Butko, V. M. Zhivun, K. V. Pavlov, V. I. Rogov, A. Yu. Titarenko, R. S. Tikhonov, S. N. Florya, A. B. Koldobskiy
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  ABSTRACT: The cross sections for the monitor reactions 27Al(p, x)24Na, 27Al(p, x)22Na, and 27Al(p, x)7Be at 12 proton energies, 2605, 1598, 1199, 799, 600, 400, 249, 147.6, 97.2, 66.0, 44.6, and 40.8 MeV, have been determined with 72 × 72-mm square and 10.5-mm-diameter round aluminum foils. The rates of the reactions of the production of 24Na, 22Na, and 7Be in the foils in each irradiation run have been determined by γ spectrometry, whereas the number of protons transmitted through these foils has been determined using calibrated fast current transformers. The cross sections have been determined as the ratios of the corresponding reaction to the average proton fluence.
  Physics of Atomic Nuclei 05/2012; 74(4):507-522.
• Article: Notes on the nature of so-called intrinsic symmetries

  O. S. Kosmachev
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  ABSTRACT: We show that in some cases intrinsic symmetries are peculiar conversion or reflection of external symmetries. They form the structure of the microparticles and then determine interactions of these particles.
  Physics of Atomic Nuclei 05/2012; 74(6):930-935.
• Article: New parametrization of lorentz transformations and tachyonic motion in special theory of relativity

  E. Kapuścik
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  ABSTRACT: Assuming the existence of an invariant velocity a slightly generalized form of Lorentz transformations is derived. The group of these transformations has a simpler composition law than the group of standard Lorentz transformations has. It is shown that this new form allows the description of both subluminal and superluminal motions. It also allows to find all velocity-dependent tensors. In particular, the tachyonic momentum as a function of superluminal velocity is derived.
  Physics of Atomic Nuclei 05/2012; 74(6):919-922.
• Article: Darboux transformations in integral and differential forms for generalized Schrödinger equations

  A. A. Suzko, E. P. Velicheva
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  ABSTRACT: The Darboux transformation operator technique is applied to the generalized Schrödinger equation with a position-dependent effective mass and with linearly energy-dependent potentials. Intertwining operators are obtained in an explicit form and used for constructing generalized Darboux transformations. An interrelation is established between the differential and integral transformation operators. It is shown how to construct the quantum well potentials in nanoelectronic with a given spectrum.
  Physics of Atomic Nuclei 05/2012; 74(7):1077-1082.
• Article: Matrix hodoscopes for the Oka (Protvino) and NA62 (SPS, CERN) experimental setups

  E. N. Gushchin, V. F. Kurshetsov, V. A. Lebedev, V. I. Romanovskiy, V. K. Semenov, S. N. Filippov, A. A. Khudyakov
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  ABSTRACT: The matrix hodoscope of the OKA experimental setup and a prototype of the hodoscope for the NA62 experiment are described. The design of both hodoscopes is presented. The requirements for the hodoscope prototype are listed, and the efficiency and the time resolution obtained on the basis of experimental data are quoted.
  Physics of Atomic Nuclei 05/2012; 74(5):783-787.
• Article: Cross sections for 68Ge production in natural- and enriched-germanium targets irradiated with protons of energy 100 MeV and background in experiments devoted to searches for the 2β0ν decay of 76Ge

  I. R. Barabanov, L. B. Bezrukov, S. V. Kianovsky, V. N. Kornoukhov
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  ABSTRACT: The rate of 68Ge production at sea level under the effect of the nuclear component of cosmic rays is calculated. The calculation is based on the experimental values of the cross sections for 68Ge production in natural- and enriched-germanium targets (enrichment in 76Ge) irradiated with high-energy protons. The background from the decays of 68Ge can be a serious problem in new-generation experiments devoted to searches for the 2β0ν decay of 76Ge.
  Physics of Atomic Nuclei 05/2012; 73(11):1809-1813.
• Article: Large-scale shell-model calculations for even-odd 61−65Fe isotopes

  P. C. Srivastava, I. Mehrotra
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  ABSTRACT: Large-scale shell-model calculations have been performed to calculate the negative-parity states of even-odd 61−65Fe isotopes. The results are compared with the recent experimental data reported at Legnaro National Laboratories and also with earlier calculations with fpg interaction in a truncated configuration space. It is observed that negative parity states of 61Fe can be well reproduced with GXPF1A interaction in full fp space without truncation. For 63Fe the correct ordering of levels is not reproduced. The structure of the wave function for the ground state and first excited state suggests that the ordering of the single-particle energy levels gets modified due to monopole correction.
  Physics of Atomic Nuclei 05/2012; 73(10):1656-1659.
• Article: Quasiaverages and classification of equilibrium states of condensed media with spontaneously broken symmetry

  N. N. Bogolyubov, D. A. Demyanenko, M. Y. Kovalevsky, N. N. Chekanova
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  ABSTRACT: Classification of equilibrium states of condensed media with spontaneously broken symmetry is carried out. Conditions of residual symmetry and spatial symmetry are formulated. The connection between these symmetry conditions and equilibrium states of various media with tensor order parameter is found out. Superfluid 3He, liquid crystals, quadrupolar magnetics are considered in detail. Possible homogeneous and heterogeneous states are found out. Discrete and continuous thermodynamic parameters, which define an equilibrium state, allowable form of order parameter, residual symmetry, and spatial symmetry generators are established.
  Physics of Atomic Nuclei 05/2012; 72(5):761-767.
• Article: Fragmentation energy shift of giant nuclear resonances

  B. A. Tulupov, M. H. Urin
  Physics of Atomic Nuclei 05/2012; 72(4):737-739.
• Article: Dynamical simulation of the fission process involving one or two degrees of freedom: Effect on fission times

  I. I. Gontchar
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  ABSTRACT: The effect of taking into account an additional (with respect to the main fission degree of freedom) collective degree of freedom on mean fission times is studied on the basis of a modified combined dynamical and statisticalmodel. It is shown that, in just the same way as within the one-dimensionalmodel, the mean fission time as a function of the angular momentum of the primary nucleus is nonmonotonic, having the shape of a curve featuring a maximum. The same applies to the dependence of the mean fission time on the fissility parameter of the primary nucleus.
  Physics of Atomic Nuclei 05/2012; 72(10):1659-1663.
• Article: Asymptotics of Raynal-Revai coefficients at large hypermomentum

  V. V. Pupyshev
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  ABSTRACT: The Raynal-Revai coefficients are studied as the Wigner D functions of O(6) group generated by the kinematical rotation of two reduced Jacobi vectors in six-dimensional three-body space. These coefficients are represented as one-dimensional integrals with kernels equal to double sums of the Clebsh-Gordan coefficients and associated Legendre polynomials. Using this representation we derive the asymptotics of the Raynal-Revai coefficients at large values of the hypermomentum.
  Physics of Atomic Nuclei 05/2012; 72(5):845-848.
• Article: Analysis of the φ → γπη and φ → γπ0π0 decays

  N. N. Achasov, V. V. Gubin
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  ABSTRACT: We study interference patterns in the φ → (γa 0+π 0 ρ) → γπη and φ → (γf 0+π 0 ρ) → γπ 0 π 0 reactions. Taking into account the interference, we fit the experimental data and show that the background reaction does not distort the π 0 η spectrum in the decay φ → γπη everywhere over the energy region and does not distort the π 0 π 0 spectrum in the decay φ → γπ 0 π 0 in the wide region of the π 0 π 0-system invariant mass, π ππ > 670 MeV, or when the photon energy is less than 300 MeV. We discuss the details of the scalar meson production in the radiative decays and note that there are reasonable arguments in favor of the one-loop mechanism φ → K + K − → γa 0 and φ → K + K − → γf 0. We also discuss distinctions between the four-quark, molecular, and two-quark models and argue that the Novosibirsk data give evidence in favor of the four-quark nature of the scalar a 0(980) and f 0(980) mesons.
  Physics of Atomic Nuclei 05/2012; 65(8):1528-1536.