Nuclear Theory·nucl-th

Friday·March 25, 2016

12 papers—10 primary·2 cross-listed

01
Exact solution of the pairing problem for spherical and deformed systems
Chong Qi · Tao Chen
There has been increasing interest in studying the Richardson model from which one can derive the exact solution for certain pairing Hamiltonians. However, it is still a numerical challenge to solve the nonlinear equations involved. In this paper we tackle this problem by employing a simple hybrid polynomial approach. The method is found to be robust and is valid for both deformed and nearly spherical nuclei. It also provides important and convenient initial guesses for spherical systems with large degeneracy. As an example, we apply the method to study the shape coexistence in neutron-rich Ni isotopes.
nucl-thPRC(2015)·22 citations
02
Analysis of experimental series of plutonium nitrate in aqueous solution and their correlation coefficients
Robert Kilger · Fabian Sommer · Maik Stuke
In this work we performed a detailed analysis on the calculation of 43 critical experiments from 6 experimental series all describing plutonium nitrate in aqueous solution contained in metal spheres. The underlying experimental data is taken from the handbook of the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Working Group. We present our modeling assumptions which were derived from the interpretation of the experimental data and discuss the resulting sensitivity analysis. Although the experiments share some components, the derived correlation coefficients are for many cases statistically not significant. Comparing our findings for the correlation coefficients with available data from the DICE Database we find an agreement for the correlation coefficients due to nuclear data. We also compare our results for the correlation coefficients due to experimental uncertainty. Our findings indicate that for the reliable Determination of correlation coefficients a detailed study of the underlying experimental data, the modeling approach and assumptions, and the resulting sensitivity analysis seems to be inevitable.
nucl-thphysics.data-anphysics.ins-detAnnals Nucl.Energy(2016)·0 citations
03
Velocity operator approach to quantum fluid dynamics in a three-dimensional neutron-proton system
Seiya Nishiyama · Joao da Providencia
In the preceeding paper, introducing isospin-dependent density operators and defining exact momenta (collective variables), we could get an exact canonically momenta approach to a one-dimensional (1D) neutron-proton (NP) system. In this paper, we attempt at a velocity operator approach to a 3D NP system. Following Sunakawa, after introducing momentum density operators, we define velocity operators, denoting classical fluid velocities. We derive a collective Hamiltonian in terms of the collective variables.
nucl-thIJMPE(2016)·2 citations
04
Searching for high- $K$ isomers in the proton-rich $A \sim 80$ mass region
Z. J. Bai · C. F. Jiao · Y. Gao · F. R. Xu
Configuration-constrained potential-energy-surface calculations have been performed to investigate the $K$ isomerism in the proton-rich $A \sim 80$ mass region. An abundance of high- $K$ states are predicted. These high- $K$ states arise from two and four-quasi-particle excitations, with $K^{π} = 8^{+}$ and $K^{π} = 1 6^{+}$ , respectively. Their excitation energies are comparatively low, making them good candidates for long-lived isomers. Since most nuclei under studies are prolate spheroids in their ground states, the oblate shapes of the predicted high- $K$ states may indicate a combination of $K$ isomerism and shape isomerism.
nucl-thCPC(2016)·2 citations
05
Three-body model for an isoscalar spin-triplet neutron-proton pair in $^{102} Sb$
Yusuke Tanimura🇫🇷 · Hiroyuki Sagawa🇯🇵
We discuss the isoscalar $T = 0, S = 1$ pairing correlation in the low-lying states of $^{102} Sb =^{100} Sn + p + n$ nucleus. To this end, we employ $core + p + n$ three-body model with the model space constructed by self-consistent mean-field calculations. The model is developed with both non-relativistic and relativistic effective interactions, the latter of which are found to be more realistic for the present case due to the pseudo-spin symmetry. It turns out that the $(L, S, T) = (0, 1, 0)$ pairing scheme is strongly hindered in $^{102}$ Sb with the relativistic model because of the near degeneracy of the $g_{7/2}$ and $d_{5/2}$ orbitals in the valence space. This pair-breaking effect is clearly seen in the charge-exchange Gamow-Teller-type transitions rather than in the binding energies of $T = 0$ and $T = 1$ states.
nucl-thPRC(2016)·4 citations
06
Strange Quark Stars as Probe of Dark Matter
Hao Zheng🇨🇳 · Lie-Wen Chen🇨🇳
We demonstrate that the observation of old strange quark stars (SQSs) can set important limits on the scattering cross sections $σ_{q}$ between the light quarks and the non-interacting scalar dark matter (DM). By analyzing a set of 1403 of solitary pulsarlike compact stars in the Milky Way, we find the old solitary pulsar PSR J1801-0857D can set the most stringent upper limits on $σ_{q}$ or the DM-proton scattering cross sections $σ_{p}$ . By converting $σ_{q}$ into $σ_{p}$ based on effective operator analyses, we show the resulting $σ_{p}$ limit by assuming PSR J1801-0857D to be a SQS could be comparable with that of the current direct detection experiments but much weaker (by several orders of magnitude) than that obtained by assuming PSR J1801-0857D to be a neutron star (NS), which requires an extremely small $σ_{p}$ far beyond the limits of direct detection experiments. Our findings imply that the old pulsars are favored to be SQSs rather than NSs if the scalar DM were observed by future terrestrial experiments.
nucl-thastro-ph.COastro-ph.SRhep-ph+1ApJ(2016)·20 citations
07
Self-energies of ground-state octet and decuplet baryon states due to the coupling to the baryon-meson continuum
H. García-Tecocoatzi🇮🇹 · R. Bijker🇲🇽 · J. Ferretti🇨🇳 · E. Santopinto🇮🇹
We present an unquenched quark model calculation of the mass shifts of ground-state octet and decuplet baryons due to the coupling to the meson-baryon continuum. The $q q ˉ$ pair-creation effects are taken explicitly into account through a microscopic, QCD-inspired, quark-antiquark pair- creation mechanism.
nucl-thEPJA(2017)·27 citations
08
Can we obtain a "new femtoscopy" on the basis of electromagnetic effects?
Andrzej Rybicki🇵🇱 · Antoni Szczurek🇵🇱 · Miroslaw Kielbowicz🇵🇱 · Nikolaos Davis🇵🇱 · Vitalii Ozvenchuk🇵🇱
We review our studies of spectator-induced electromagnetic (EM) effects on charged pion emission in ultrarelativistic heavy ion collisions. These effects are found to consist in the electromagnetic {charge splitting} of pion directed flow as well as very large distortions in spectra and ratios of produced charged particles. As it emerges from our analysis, they offer sensitivity to the actual distance $d_{E}$ between the pion formation zone at freeze-out and the spectator matter. As a result, this gives a new possibility of studying the space-time evolution of dense and hot matter created in the course of the collision. Having established that $d_{E}$ traces the longitudinal evolution of the system and therefore rapidly decreases as a function of pion rapidity, we investigate the latter finding in view of pion feed-over from intermediate resonance production. As a result we obtain a first estimate of the pion decoupling time from EM effects which we compare to existing HBT data. We conclude that spectator-induced EM interactions can serve as a new tool for studying the space-time characteristics and longitudinal evolution of the system.
nucl-thhep-exhep-phActa Phys.Polon.Supp.(2016)·10 citations
09
Saturation properties of nuclear matter in the presence of strong magnetic field
Z. Rezaei · G. H. Bordbar
Different saturation properties of cold symmetric nuclear matter in the strong magnetic field have been considered. We have seen that for magnetic fields about $B > 3 \times 1 0^{17} G$ , {for both cases with and without nucleon anomalous magnetic moments}, the saturation density and saturation energy grow by increasing the magnetic field. It is indicated that the magnetic susceptibility of symmetric nuclear matter becomes negative showing the diamagnetic response especially at $B < 3 \times 1 0^{17} G$ . We have found that for the nuclear matter, the magnitude of orbital magnetization reaches the higher values comparing to the spin magnetization. Our results for the incompressibility show that at high enough magnetic fields, i.e. $B > 3 \times 1 0^{17} G$ , {the softening of equation of state caused by Landau quantization is overwhelmed by stiffening due to the magnetization of nuclear matter.} We have shown that the effects of strong magnetic field on nuclear matter may affect the constraints on the equation of state of symmetric nuclear matter obtained applying the experimental observable.
nucl-thastro-ph.SREPJA(2016)·9 citations
10
Three-cluster breakup in deuteron-deuteron collisions: single-scattering approximation
A. Deltuva · A.C. Fonseca
We present results for the three-cluster breakup in deuteron-deuteron collisions at 130 and 270 MeV deuteron beam energy. The breakup amplitude is calculated using the first term in the Neumann series expansion of the corresponding exact four-nucleon equations. In analogy with nucleon-deuteron breakup where an equivalent approximation is compared with exact calculations, we expect this single-scattering approximation to provide a rough estimation of three-body breakup observables in quasifree configurations. We predict the nucleon-deuteron and deuteron-deuteron three-cluster breakup cross sections to be of a comparable size and thereby question the reliability of the recent experimental data [A. Ramazani-Moghaddam-Arani, Ph.D. thesis, University of Groningen, 2009; A. Ramazani-Moghaddam-Arani et al., EPJ Web of Conferences 3, 04012 (2010)] that is smaller by about three orders of magnitude. We also show that an equivalent single-scattering approximation provides a reasonable description of deuteron-deuteron elastic scattering at forward scattering angles.
nucl-thnucl-exPRC(2016)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE