Nuclear Physics A最新文献

Neutrino-nucleus reaction cross sections on ¹⁸O are evaluated by shell-model calculations and compared with those on ¹⁶O. Important contributions from Gamow-Teller transitions are noticed for ¹⁸O (${\nu }_e$, e⁻) ¹⁸F in contrary to the case for ¹⁶O, where spin-dipole transitions are dominant contributions. Calculated cross sections for ¹⁸O (${\nu }_e$, e⁻) ¹⁸F are shown to be larger than for ¹⁶O at low neutrino energies below 20 MeV in natural water with the 0.205% admixture of ¹⁸O due to the lower threshold energy (1.66 MeV) for ¹⁸O than that for ¹⁶O (15.42 MeV). The resulting electron spectra, that is, the cross sections as functions of emitted electron energy $T_e$, are also shown to be quite different, reflecting the different threshold energies. The electron spectra from (${\nu }_e$, e⁻) reactions on ¹⁸O and ¹⁶O in water Cherenkov detectors for supernova neutrino detection are investigated for both the cases with and without the neutrino oscillation and compared with those of the neutrino-electron scattering. It has been shown that the contribution from ¹⁸O (0.205% mixture) enhances the rates from ¹⁶O by 60% for the case without the oscillation and by 20-30% for the case with the oscillation below $T_e$ =20 MeV. For the case with the neutrino oscillation, the event rates for ¹⁸O and ¹⁶O become comparable to those of the neutrino-electron scattering. However, their rates at low energy ($T_e<$ 20 MeV) are much lower than those of the neutrino-electron scattering, which is important for the pointing accuracy to the supernova direction.

Considering various initial deformations, the ground, first excited, and second excited states binding energies are calculated using the effective field theory motivated relativistic mean-field based IOPB-I force parameter. The alpha decay chains for both the ²⁰⁷Th and ²⁰⁸Th are examined. As observed for both nuclei, it takes four subsequent α-particle emissions to reach the stable Pb nucleus. The half-lives determined by two widely used Viola-Seaborg and modified universal decay law formulas are compared with the available experimental data. The surface property-like symmetry energy is also predicted for these nuclei in the framework of the coherent density fluctuation model and establishes a connection between the decay behavior and the symmetry energy.

We present a cluster expansion EoS model for strongly-interacting matter based on the generalized Beth-Uhlenbeck formalism to describe hadrons as bound clusters of quarks. This formalism can describe both confined and deconfined phases. Our emphasis is on the region of vanishing baryon densities, where numerical solutions available from Lattice QCD predict a smooth crossover transition from hadron to quark matter. Medium effects are taken into account as self energies, which are motivated from both perturbative QCD calculations and phenomenological models. Parameters are tuned to Lattice QCD data and result in a good agreement of the thermodynamics.

The production cross-section of ⁶⁸Ge, ⁶⁹Ge, ⁶⁵Zn and ⁶⁷Ga radioisotopes from alpha-induced nuclear reaction with ${}^{nat}$Zn have been measured using the stacked foil activation technique followed by the off-line γ-ray spectroscopy in the incident alpha energy range 14-37 MeV. The obtained nuclear reaction cross-sections are compared with previous experimental data available in the EXFOR data library, evaluated nuclear data from TENDL-2019 and theoretical results, calculated using TALYS nuclear reaction code. We have also performed the detailed uncertainty analysis for these nuclear reactions and their respective correlation metrics are presented. Since α-induced reactions are important in nuclear medicine and developing the nuclear reaction codes so needful corrections related to the coincidence summing factor and the geometric factor have been considered during the data analysis in the present study.

Quantum computing raises the possibility of solving a variety of problems in physics that are presently intractable. A number of such problems involves the physics of systems in or near thermal equilibrium. There are two main ways to compute thermal expectation values on a quantum computer: construct a thermal state that reproduces thermal expectation values, or sample various energy eigenstates from a Boltzmann distribution of a given temperature. In this paper we address the second approach and propose an algorithm that uses active cooling to produce the distribution. While this algorithm is quite general and applicable to a wide variety of systems, it was developed with the specific intention of simulating thermal configurations of non-Abelian gauge theories such as QCD, which would allow the study of quark-gluon plasma created in heavy-ion collisions.

The present work is carried out to see the role of double spin-orbit parameters (W₁ and W₂) on reactions having spherical-prolate, spherical-oblate, oblate-prolate and oblate-oblate configurations. For the study, semi-classical Skyrme energy density formalism is used by employing SkIx (x=2,3,4) and SAMi Skyrme forces. The calculations suggest that the presence of double spin-orbit strength imparts significant influence on spin-dependent potential (V_J) as maximum barrier height of $V_J$ (V${}_{JB}$) is observed with SAMi force (W₁≠W₂) and minimum with SkI2 (W₁=W₂) i.e., V${}_{JB}$${}_{\left(SAMi\right)}$>V${}_{JB}$${}_{\left(SkI4\right)}$>V${}_{JB}$${}_{\left(SkI3\right)}$>V${}_{JB}$${}_{\left(SkI2\right)}$. The maxima and minima in $V_{JB}$ are further related to the contribution from the isoscalar and isovector parts of the spin-orbit potential. As far as shape of projectile and(or) target is concerned, the higher V${}_{JB}$ is obtained for oblate-prolate configuration and lower when spherical-prolate configuration is used. The chosen Skyrme forces also modify the fusion barrier height V_B of different target-projectile combinations in the similar way as the spin-orbit barrier height (V${}_{JB}$) does. These Skyrme forces are further applied to address the experimental fusion excitation functions and fusion barrier distributions of the considered reacting partners. The contribution of V_J is also estimated in fusion cross-section of considered reactions.

Based on Keras deep learning framework, the feedforward neural network (FNN) model is employed to improve the predictions of the liquid drop model (LDM). It is shown that the prediction ability of FNN can be significantly improved if multiple hidden layers are used with only four input parameters. The root-mean-square deviation (RMSD) of nuclear mass predicted by LDM can be reduced from 2.38 MeV to 196 keV with the multi-hidden-layer FNN model, which is only one third of the single-hidden-layer FNN model. The predictions of two-neutron separation energies (S_2n) and single-neutron separation energies ($S_n$) indicate that the multi-hidden-layer FNN model gives a better description of the shell structure. In addition, the extrapolation capability of the model in the super-heavy nuclear region is studied, the results show that better extrapolation capability can be achieved if multiple hidden layers are employed.