International Journal of Modern Physics E

The spectroscopic properties play a crucial role in understanding the structure of nuclei, in particular, the shape and shape transitions of nuclei. In recent years, the exotic shapes of nuclear systems, such as the rod and pear shapes, have attracted a lot of attention. Covariant density functional theory (CDFT) has become a standard tool for nuclear structure calculations, and it provides a global and accurate description of nuclear ground states and excitations. In the present paper, we briefly review the recent progress in covariant density functional theory (DFT) for spectroscopic properties of the rod- and pear-shaped nuclei with the cranking calculations in a rotating mean field and the collective Hamiltonian method beyond mean field. The novel linear-chain structure of alpha clustering is discussed with the cranking approach, and low lying spectra of pear-shaped nuclei are illustrated with the quadrupole–octupole collective Hamiltonian.

The systematics of neutron-induced reactions at 14.5MeV are of great importance to describe the excitation of nuclei for the $(n,p)$ reactions. In this study, a new empirical formula is obtained by introducing the proton separation energy to the principal empirical formula for estimating the $(n,p)$ reaction cross-sections for 77 nuclei in the light element mass number range $19\le A\le 101$ at the incident neutron energy of 14.5MeV. The calculated results are compared with the evaluated data declared by the TENDL nuclear data library. The predictions of our formula reveal better agreement with the experimental data than the results obtained from the previous suggested formulae.

We investigate the role of suspected resonance states, that are yet to be confirmed experimentally, on different thermodynamic quantities as well as the higher-order fluctuations and the correlation between conserved charges using ideal hadron resonance gas (HRG) model. We have discussed the temperature dependence of the various thermodynamic quantities and compared them with the lattice QCD result. We observe that the values of the bulk thermodynamic variables such as pressure, energy density, entropy density and second-order susceptibilities are increased by the inclusion of the additional resonances. Further, we find that the hadronic phase of lattice QCD result of ${\chi }_S^2,{\chi }_{BS}^{11}$ and ${\chi }_{QS}^{11}$ can be described well in ideal HRG model with the additional resonances. We have also studied the $\sqrt{s_{NN}}$ dependence of the fluctuation observables of net-proton, net-kaon and net-charge. Proper experimental acceptance cuts have been used in the model to compare with the data from experimental measurements. It has been observed that the experimental data of lower-order fluctuation observable can be described well by the ideal HRG model. However, higher-order fluctuation observables cannot be described by ideal HRG model for all $\sqrt{s_{NN}}$ studied here, which indicates the possibility of presence of critical or nonequilibrium physics for those energies. The effect of additional resonances on fluctuation observables of net-charge at different $\sqrt{s_{NN}}$ has also been studied. Finally, the chemical freeze-out parameters have been extracted from the experimental data of ${\sigma }^2/M$ of net-proton and net-charge using two different sets of hadronic spectra. We find that for both the sets, the extracted temperature is slightly lower than those obtained from the hadronic yields. Moreover, it is observed that the extracted temperature of the system gets further reduced with addition of more resonances.

An overall description of the cross-sections and tensor analyzing powers corresponding to the elastic interaction ${}^{12}\mathrm{\text{C}}({}^7\overrightarrow{\mathrm{\text{Li}}},{}^7\mathrm{\text{Li}}){}^{12}\mathrm{\text{C}}$ at $E_{\mathrm{\text{lab}}}({}^7\mathrm{\text{Li}})=34\mathrm{\text{MeV}}$ has been obtained with a coupled channel analysis using the rotational model. Based on the high electric quadrupole moment of the ${}^7\mathrm{\text{Li}}$ projectile, an optical model potential equal to the sum of a quadrupole deformed generalized Woods–Saxon potential and a standard Spin-Orbit term has been used. The deformed part of the potential induces reorientations and transitions that involve the first four energy states of the ${}^7\mathrm{\text{Li}}$ nucleus. These states are supposed to belong to an inverted $K$$=$$1/2$ rotational band proposed in the literature. Partial reproductions of the inelastic interaction ${}^{12}\mathrm{\text{C}}({}^7\overrightarrow{\mathrm{\text{Li}}},{}^7{\mathrm{\text{Li}}}_{0.4776\mathrm{\text{MeV}}}^{\ast }){}^{12}\mathrm{\text{C}}$ have also been achieved by using the same deformed potential with the same parameter values that describe the elastic interaction. Comparisons are made with previous results obtained from optical model potential and continuum-discretized coupled-channel calculations using the cluster-folding model. The use of a deformed scattering potential introduces a tensor term that allows the reproduction of the tensor analyzing powers.

All three components of the tensor analyzing power for the reaction of ${\pi }^{-}$-meson photoproduction on a deuteron have been measured in photon energy range of 280–500MeV and proton energy range of 15–70MeV. The experiment has been conducted on an internal tensor-polarized deuterium gas target of the VEPP-3 electron storage ring using the method of detecting two final protons in coincidence. Measured components of the tensor analyzing power have been compared with calculations results obtained within the framework of diagrammatic approach.

In this paper, we present the effect of a strong magnetic field in the burning of a neutron star (NS). We have used relativistic magneto-hydrostatic (MHS) conservation equations for studying the PT from nuclear matter (NM) to quark matter (QM). We found that the shock-induced phase transition (PT) is likely if the density of the star core is more than three times nuclear saturation (${\rho }_s$) density. The conversion process from NS to quark star (QS) is found to be an exothermic process beyond such densities. The burning process at the star center most likely starts as a deflagration process. However, there can be a small window at lower densities where the process can be a detonation one. At small enough infalling matter velocities the resultant magnetic field of the QS is lower than that of the NS. However, for a higher value of infalling matter velocities, the magnetic field of QM becomes larger. Therefore, depending on the initial density fluctuation and on whether the PT is a violent one or not the QS could be more magnetic or less magnetic. The PT also have a considerable effect on the tilt of the magnetic axis of the star. For smaller velocities and densities the magnetic angle are not affected much but for higher infalling velocities tilt of the magnetic axis changes suddenly. The magnetic field strength and the change in the tilt axis can have a significant effect on the observational aspect of the magnetars.

Nuclear flow observable has been investigated systematically for the collision of nearly symmetric nuclei ${}_{79}^{197}\mathrm{\text{Au}}+{}_{79}^{197}\mathrm{\text{Au}},$ ${}_{60}^{150}\mathrm{\text{Nd}}+{}_{60}^{150}\mathrm{\text{Nd}},$ ${}_{54}^{131}\mathrm{\text{Xe}}+{}_{50}^{118}\mathrm{\text{Sn}},$ ${}_{40}^{96}\mathrm{\text{Zr}}+{}_{40}^{96}\mathrm{\text{Zr}},$ ${}_{28}^{58}\mathrm{\text{Ni}}+{}_{28}^{58}\mathrm{\text{Ni}}$ and ${}_{18}^{40}\mathrm{\text{Ar}}+{}_{21}^{45}\mathrm{\text{Sc}}$. Both balance and transition energies are found to be dependent on various input parameters like composite mass of the colliding nuclei, incident energy and impact parameter bins of the reaction. In addition to this, it has been concluded that power law behavior is perceived in both the balance and transition energies. Transition energy is more suitable to study the behavior of compressed nuclear matter. In this paper, we found that squeeze out phenomenon is helpful to understand the reaction dynamics.

The properties of odd nuclei have been investigated within the collective model by assuming the system is composed of a single nucleon in the $j=3/2$ single particle orbit coupled to a $\gamma$-unstable even-core. The Davidson potential has been used in the corresponding Bohr Hamiltonian for the even core. The excitation energy spectrum and the electric quadrupole transition ratios have been obtained. The results have been used to predict the experimental data of the some selected odd isotopes.

In this paper, we investigate the possible mechanisms, which are responsible for the production of slow target fragments with energy $\le 400$MeV that are emitted from interactions of ${}^{28}$Si nucleus with emulsion nuclei at energy 14.6GeV per nucleon. Angular distributions of slow fragments are compared with the corresponding results from collisions of ¹H, ³He, ⁴He, ⁷Li and ${}^{12}$C with emulsion at the energy range 2.2–3.7AGeV. We investigate the effects of both projectile energy and mass number on the angular distributions for slow secondary charged fragments called gray and black track producing particles. The average emission angles are found to be ${64}^{\circ }$ and ${82}^{\circ }$ for gray and black tracks, respectively. These values are nearly constant for all compared experiments. There are two different mechanisms of gray particle production in forward and backward directions while there is a single symmetric mechanism for black particles in both directions. The temperatures are found to be 58 and 6MeV for systems of emissions for gray and black particles, respectively. There are strong effects of target size on those mechanisms. The emission system of these particles becomes slower and shows low temperature with the increase in volume of target nucleus.

In this work, we extend a previous study of matrix models of strength distributions. We still retain the nearest neighbor coupling mode but we extend the values of the coupling parameter $v$. We consider extremes, from very small $v$ to very large $v$. We first use the same transition operator as before $〈nT(n+1)〉=\mathrm{\text{constant}}(=1)$. For this case, we get an exponential decrease for small $v$, as expected, but we get a phase transition beyond $v$=10, where we get separate exponentials for even $n$ and for odd $n$. We now also consider the dipole choice where $〈nT(n+1)〉=\sqrt{(n+1)}$.

The model of multiple Dirac eikonal scattering (MDES) of incident proton by target-nucleus nucleons is developed, in which new expressions for the elastic $pA$-scattering amplitudes are obtained from the multiple scattering Watson series with employing the eikonal approximation for the Dirac propagators of the free proton motion between successive scattering acts on nucleons. Based on this model, calculations for the complete set of observables of the elastic $p+{}^{40}\mathrm{\text{Ca}}$ and $p+{}^{208}$Pb at 800MeV have been performed, using proton–nucleon amplitudes determined from the phase analysis and the nucleon densities obtained from describing the target-nucleus structure in the relativistic mean-field approximation. A comparison has been made of the results of these calculations with analogous calculations on the basis of the Glauber multiple diffraction theory.

We have measured the differential cross-sections for the elastic as well as inelastic scattering populating the 2.43MeV $(5/2^{-})$ excited state in ${}^9\mathrm{\text{Be}}$ using ${}^3\mathrm{\text{He}}$ beams at energies of 30, 40 and 47MeV on a ${}^9\mathrm{\text{Be}}$ target. The experimental results for the elastic scattering were analyzed within the framework of the optical model using the Woods–Saxon and double-folding potentials. The theoretical calculations for the concerned excited states were performed using the coupled-channel method. The optimal deformation parameters for the excited states of ${}^9\mathrm{\text{Be}}$ nucleus were extracted.