查看更多>>摘要：We have checked the sensitivity of different observables such as fragment multiplicities, anisotropy ratios and N/Z ratios of free and bound nucleons towards the density dependence of nuclear symmetry energy for different mass asymmetric reactions at beam energy of 20 MeV/nucleon. These investigations revealed that neutron-to-proton ratios of free particles and the power-law exponent obtained from the mass dependence of these ratios in mass asymmetric reactions are highly sensitive to density dependence of symmetry energy and could be utilized to constrain nuclear symmetry energy. Comparison of our calculations with available measurements at low energies favors softer symmetry energy at sub-saturation densities. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The current research intends to investigate the shape evolution and ground-state properties of even-even isotopic chains of Oxygen (Z = 8, N = 12 - 28), Calcium (Z = 20, N = 34 - 60), Nickel (Z = 28, N = 48 - 80), and Tin (Z = 50, N = 100 - 134) by using the DD-PCX parameterization based on covariant density functional theory. The covariant density functional theory is a popular theoretical tool for the description of nuclear structure phenomena. The nuclear properties of interest are potential energy surfaces, the binding energy per nucleon, two-neutron separation energy, differential variation of two-neutron separation energy, neutron rms radius, protons rms radius, and neutron skin thickness. The Covariant mass data and Skyrme mass data were very helpful to provide a comparative ground for better comparison of our data and testing the efficiency of DD-PCX parameterization. The effective interaction DD-PCX was designed to accurately calculate the neutron-skin thickness, and the comparative analysis present in the result section demonstrates that. We have observed the shape transition from spherical to oblate and oblate to spherical for Ni-60(Z=28, N=32) and Ni-66(Z=28, N=38) in our studies. We have observed the oblate shape in Ni-60, Ni-62, and Ni-64. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The He-3(alpha, gamma )Be-7 reaction is important for the solar hydrogen burning and the Big Bang Nucleosynthesis. The cross sections at astrophysical energies have not yet been precisely determined, the extrapolation has to rely on the full excitation spectrum of Be-7. A controversy 3/2(+) resonance state firstly reported in the study of the Li-6(p, gamma )Be-7 reaction has attracted many attentions in the recent years. In this work, both reactions of He-3(alpha, gamma )Be-7 and Li-6(p, gamma )Be-7 are reanalyzed together in the formalism of R-matrix with and without the 3/2(+) state in Be-7. The results show that this nonnormal state cannot be ruled out based on existing data. According to the present analysis, the 3/2(+) resonance does not have a significant impact on the He-3(alpha, gamma )Be-7 reaction at astrophysical energies, but the accurate measurement of the cross sections of He-3(alpha, gamma )Be-7 at E-cm > 4 MeV can be used as a verification for the existence of the state. (C) 2022 Published by Elsevier B.V.
查看更多>>摘要：This study investigates the thermodynamical properties of magnetized strange quark matter (MSQM) and magnetized strange quark stars (MSQSs), the longitudinal and transverse equation of state (EoS), the maximum mass, the love number, tidal deformability, and gravitational redshift for MSQSs in chiral SU(3) quark mean-field (CQMF) model. The effects of vector interactions and density-dependent magnetic field are considered in the calculations. The EoS having longitudinal pressure gets soften with an increase in magnetic field and becomes stiffer for transverse pressure. The derived results show that the maximum mass of SQSs depends not only on the strength of the magnetic field but also on the orientation of the magnetic field inside the stars. The maximum mass and tidal deformability of MSQSs show good agreement with both the constraints of PSR J0030+0451 measured by NICER and the tidal deformability of gravitational wave event (GW170817) observed by LIGO and Virgo collaboration. In addition, the structure of MSQS is investigated using an axially symmetric metric with spherical coordinates in which gamma - parameter observes the deformation of the star due to magnetic field.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Jet handedness as a measure of quark and/or gluon polarizations has been proposed for nearly 30 years. It was demonstrated by measuring the correlation of jet handedness in the electron positron annihilation process. Once parameters are determined, the method could be used to measure quark and/or gluon polarizations in other experiments. The reported data provided evidence for the jet handedness and handedness correlation. However, the jet handedness correlation measured in the electron positron annihilation process from the opposite jets contradicts theoretical prediction by a sign. In order to explain this, we present a chromo-hydrogen-like model in this paper. According to calculations, both jet handedness and handedness correlation depend on not only the polarization of the fragmenting valence quark but also the polarization of the sea quark. It is the appearance of the sea quark polarization that can solve the contradiction. In other words, measurements of jet handedness and handedness correlation can be used to determine the sea quark polarization. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, we tried to investigate the possible correlation of inter and intra-band quadrupole transition probabilities of rotational bands. To this aim, all the available experimental values of quadrupole transition rates between different levels of the ground band together quadrupole transitions of gamma and beta bands, 2(y)(+)-> 0(g)(+) and 2(beta)(+) -> 0(g)(+), of even-even prolate nuclei in the 150 < A < 250 mass region are analyzed. We extended the kernel density estimation approach as a non-parametric estimation formalism for this analysis and compared its predictions with the results of the commonly used parametric technique with emphasis on Porter-Thomas distribution. The results show that the statistical correlation is dominant for such inter band transitions between different levels of the ground band but for intra-band transitions which originated from the beta band, deviation from correlated behavior is obvious. Also, the comparison of the statistical behavior of 2(+) -> 0(+) transitions of different rotational bands, suggests the most GOE-like behavior for the quadrupole transitions between the levels of the ground band. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The paper studies the effects that arise at the coherent excitation of the anomalously low-lying isomeric level 3/2+(8.19 +/- 0.12 eV) in the 229Th nucleus driven by laser radiation in wide band gap dielectrics. It is shown that in such an excitation a) the appearance of additional decay channels with a width Gamma of the 229mTh isomer due to electron states in the band gap leads to an effective "freezing" of the system in the ground state (the repopulation process at relatively small Gamma and the Zeno effect at large Gamma), making the process of nuclear excitation practically impossible, b) the probability of the alpha decay of a coherent superposition of the ground and isomeric states becomes equal to the half-sum of the alpha widths of both levels and is increased by about a factor of two in comparison with the probability of the alpha decay of 229Th, c) the intensity of the main alpha lines oscillates with the Rabi frequency and the total alpha spectrum shifts towards higher energies for long time measurements, d) the inverse population of nuclear levels required for the Thorium gamma ray laser is achieved relatively quickly within the ir pulse duration, e) the observation of the Zeno effect according to the Cook's scheme is possible for the system of three lower levels of the 229Th nucleus. (c) 2022 Elsevier B.V. All rights reserved.
Saraswat, KapilRawat, Deependra SinghChandola, H. C.
17页
查看更多>>摘要：In the present analysis, we compute the energy loss of heavy quarks (charm and bottom) due to elastic collisions and gluon radiation in proton-Lead (p-Pb) collisions at root SNN = 5.02 TeV. We calculate the collisional energy loss using Peigne and Peshier formalism and radiative energy loss using the generalised dead cone approach and reaction operator formalism. We also calculate the fluctuations in the resulting medium using the CMT (Chakraborty, Mustafa and Thoma) formalism. The nuclear modification factors RpPb including shadowing, energy loss and fluctuations are calculated for B+,0 and D+,0 mesons in p-Pb collisions at root SNN = 5.02 TeV and are compared with the recent measurements by CMS experiment. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：We analyze the time evolution of the kinetic properties of nuclear matter produced in heavy-ion collisions at Fermi energies. The collision system is simulated using Constrained Molecular Dynamics (CoMD) transport calculations whose output is the isospin, position, and momentum of the nucleons. Focusing on central 35 A & BULL;MeV 40Ca+40Ca collisions we utilize this information to extract localized momentum distributions in volume elements of 8 fm3 and time steps of 5 fm/c. We then parameterize the single-particle momentum distributions with thermally motivated fit functions in the local rest frame of each cell. While the transverse-momentum distributions are well reproduced by thermal ones, the longitudinal ones carry a marked imprint of the initial nuclear motion which we capture by introducing a centroid motion into our fit functions. In particular, we find that Fermi distributions yield significantly better fits than Boltzmann ones, a consequence of the Pauli blocking implemented in CoMD. From the fits we extract the time dependence of the thermodynamic and collective properties of the excited nuclear medium. We find that the transverse temperature gradually rises to about 6 MeV, which is accompanied by a dissipation of the initial centroid motion of the incoming nuclei which vanishes at about 100 fm/c after initial impact. We are therefore able to track the transition of beam energy into random kinetic energy for nucleons, suggesting a three-dimensional equilibration of energy in the late stages of the collision. (C) 2022 Elsevier B.V. All rights reserved.
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