Nuclear Theory·nucl-th

Thursday·September 3, 2015

11 papers—8 primary·3 cross-listed

01
Current Status of Nuclear Physics Research
C.A. Bertulani (Tamu-Commerce)🇺🇸 · M.S. Hussein (USP)🇧🇷
In this review we discuss the current status of research in nuclear physics which is being carried out in different centers in the World. For this purpose we supply a short account of the development in the area which evolved over the last 9 decades, since the discovery of the neutron. The evolution of the physics of the atomic nucleus went through many stages as more data become available. We briefly discuss models introduced to discern the physics behind the experimental discoveries, such as the shell model, the collective model, the statistical model, the interacting boson model, etc., some of these models may be seemingly in conflict with each other, but this was shown to be only apparent. The richness of the ideas and abundance of theoretical models attests to the important fact that the nucleus is a really singular system in the sense that it evolves from two-body bound states such as the deuteron, to few-body bound states, such as $^{4}$ He, $^{7}$ Li, $^{9}$ Be etc. and up the ladder to heavier bound nuclei containing up to more than 200 nucleons. Clearly statistical mechanics does not work for such finite system, neither does other theories applicable to condensed matter systems. The richness of nuclear physics stems from these restrictions. New theories and models are presently being developed. Theories of the structure and reactions of neutron-rich and proton-rich nuclei, called exotic nuclei, halo nuclei, or Borromean nuclei deal with the wealth of experimental data available in the last 35 years. Further, nuclear astrophysics and stellar and Big Bang nucleosynthesis have become a more mature subject. Due to limited space, this review only covers a few selected topics, mainly those with which the authors have worked with.
nucl-thhep-exhep-phnucl-exBraz.J.Phys.(2015)·8 citations
02
Random-matrix approach to the statistical compound nuclear reaction at low energies using the Monte-Carlo technique
T. Kawano · P. Talou · H. A. Weidenmüller
Using a random-matrix approach and Monte-Carlo simulations, we generate scattering matrices and cross sections for compound-nucleus reactions. In the absence of direct reactions we compare the average cross sections with the analytic solution given by the Gaussian Orthogonal Ensemble (GOE) triple integral, and with predictions of statistical approaches such as the ones due to Moldauer, to Hofmann, Richert, Tepel, and Weidenmüller, and to Kawai, Kerman, and McVoy. We find perfect agreement with the GOE triple integral and display the limits of validity of the latter approaches. We establish a criterion for the width of the energy-averaging interval such that the relative difference between the ensemble-averaged and the energy-averaged scattering matrices lies below a given bound. Direct reactions are simulated in terms of an energy-independent background matrix. In that case, cross sections averaged over the ensemble of Monte-Carlo simulations fully agree with results from the Engelbrecht-Weidenmüller transformation. The limits of other approximate approaches are displayed.
nucl-thPRC(2015)·41 citations
03
Neutron Capture Reactions near N=82 Shell-Closure
Saumi Dutta · Dipti Chakraborty · G. Gangopadhyay · Abhijit Bhattacharyya
Neutron capture cross-sections have been calculated in nuclei near the N=82 neutron shell closure. These nuclei are of astrophysical interest, participating in s-process and p-process. A semi-microscopic optical model have been used with the potential being obtained through folding the target density with the DDM3Y nucleon nucleon interaction. Theoretical density values have been calculated in the relativistic mean field approach. The calculated cross-section, as a function of neutron energy, agree reasonably well with experimental measurements. Maxwellian averaged cross-sections, important for astrophysical processes, have been calculated.
nucl-thPRC(2016)·15 citations
04
Airy structure in $^{16}$ O+ $^{14}$ C nuclear rainbow scattering
S. Ohkubo · Y. Hirabayashi
The Airy structure in $^{16}$ O+ $^{14}$ C rainbow scattering is studied with an extended double folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic realistic wave functions for $^{16}$ O using a density-dependent nucleon-nucleon force. The experimental angular distributions at $E_{L}$ =132, 281 and 382.2 MeV are well reproduced by the calculations. By studying the energy evolution of the Airy structure, the Airy minimum at around $θ$ =76 $^{\circ}$ in the angular distribution at $E_{L}$ =132 MeV is assigned as the second order Airy minimum $A 2$ in contrast to the recent literature which assigns it as the third order $A 3$ . The Airy minima in the 90 $^{\circ}$ excitation function is investigated in comparison with well-known $^{16}$ O+ $^{16}$ O and $^{12}$ C+ $^{12}$ C systems. Evolution of the Airy structure into the molecular resonances with the $^{16}$ O+ $^{14}$ C cluster structure in the low energy region around $E_{c . m .}$ =30 MeV is discussed. It is predicted theoretically for the first time for a non- $4 N$ $^{16}$ O+ $^{14}$ C system that Airy elephants in the 90 $^{\circ}$ excitation function are present.
nucl-thPRC(2015)·7 citations
05
Squeezed correlations of $ϕ$ meson pairs for hydrodynamic sources in high-energy heavy-ion collisions
Yong Zhang🇨🇳 · Jing Yang🇨🇳 · Wei-Ning Zhang🇨🇳
In the hot and dense hadronic sources formed in high-energy heavy-ion collisions, the particle interactions in medium might lead to a squeezed back-to-back correlation (BBC) of boson-antiboson pairs. We calculate the BBC functions of $ϕϕ$ for sources evolving hydrodynamically in ( $2 + 1$ ) dimensions and with longitudinal boost invariance. The BBC functions for hydrodynamic sources exhibit oscillations as a function of the particle momentum because the temporal distributions of hydrodynamic sources have sharp falls to 0 at large evolving times. The dependences of the BBC functions on the directions of the particle momentum are investigated. For transverse anisotropic sources, the BBC functions are minimum when the azimuthal angles of the particles reach 0. The BBC functions increase with decreasing absolute value of the particle pseudorapidity. The oscillations and the dependences on the particle azimuthal angle and pseudorapidity are the significant signatures for detecting the BBC in high-energy heavy-ion collisions.
nucl-thPRC(2015)·20 citations
06
Astrophysical S factor of { $^{12}$ C( $α, γ$ ) $^{16}$ O} Calculated with the Reduced R-matrix Theory
Zhen-Dong An🇨🇳 · Zhen-Peng Chen🇨🇳 · Yu-Gang Ma🇨🇳 · Jian-Kai Yu🇨🇳 · Ye-Ying Sun🇨🇳 · Gong-Tao Fan🇨🇳 · Yong-Jiang Li🇨🇳 · Hang-Hua Xu🇨🇳 · Bo-Song Huang🇨🇳 · Kan Wang🇨🇳
Determination of the accurate astrophysical S factor of { $^{12}$ C( $α, γ$ ) $^{16}$ O} reaction has been regarded as a holy grail of nuclear astrophysics for decades. In current stellar models, a knowledge of that value to better than 10\% is desirable. Due to the practical issues, tremendous experimental and theoretical efforts over nearly 50 years are not able to reach this goal, and the published values contradicted with each other strongly and their uncertainties are 2 times larger than the required precision. To this end we have developed a Reduced R-matrix Theory, based on the classical R-matrix theory of Lane and Thomas, which treats primary transitions to ground state and four bound states as the independent reaction channels in the channel spin representation. With the coordination of covariance statistics and error propagation theory, a global fitting for almost all available experimental data of $^{16}$ O system has been multi-iteratively analyzed by our powerful code. A reliable, accurate and self-consistent astrophysical S factor of { $^{12}$ C( $α, γ$ ) $^{16}$ O} was obtained with a recommended value $S_{t o t}$ (300) = 162.7 $\pm$ 7.3 keV b (4.5\%) which could meet the required precision.
nucl-thnucl-exPRC(2015)·21 citations
07
Heavy and superheavy elements production in high intensive fluxes of explosive process
Yu.S. Lutostansky · V.I. Lyashuk · I.V. Panov
Mathematical model of heavy and superheavy nuclei production in intensive pulsed neutron fluxes of explosive process is developed. The pulse character of the process allows dividing it in time into two stages: very short rapid process of multiple neutron captures with higher temperature and very intensive neutron fluxes, and relatively slower process with lower temperature and neutron fluxes. The model was also extended for calculation of the transuranium yields in nuclear explosions takes into account the adiabatic character of the process, the probabilities of delayed fission, and the emission of delayed neutrons. Also the binary starting target isotopes compositions were included. Calculations of heavy transuranium and transfermium nuclei production were made for Mike, Par and Barbel experiments, performed in USA. It is shown that the production of transfermium neutron-rich nuclei and superheavy elements with A ~ 295 is only possible in case of binary mixture of starting isotopes with the significant addition of heavy components, such as long-lived isotopes of curium, or californium.
nucl-th0 citations
08
Hybrid star structure with the Field Correlator Method
G. F. Burgio🇮🇹 · D. Zappala' (INFN Sezione di Catania)🇮🇹
We explore the relevance of the color-flavor locking phase in the equation of state (EoS) built with the Field Correlator Method (FCM) for the description of the quark matter core of hybrid stars. For the hadronic phase, we use the microscopic Brueckner-Hartree-Fock (BHF) many-body theory, and its relativistic counterpart, i.e. the Dirac-Brueckner (DBHF). We find that the main features of the phase transition are directly related to the values of the quark-antiquark potential $V_{1}$ , the gluon condensate $G_{2}$ and the color-flavor superconducting gap $Δ$ . We confirm that the mapping between the FCM and the CSS (constant speed of sound) parameterization holds true even in the case of paired quark matter. The inclusion of hyperons in the hadronic phase and its effect on the mass-radius relation of hybrid stars is also investigated.
nucl-thastro-ph.SRhep-phEPJA(2016)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE