Nuclear Physics A最新文献

In this paper, we tried to describe both normal and intruder levels of the ground and first excited beta and gamma rotational bands of ^162,164,166Dy deformed nuclei in the framework of the interacting boson model. A normal Hamiltonian of SU(3) dynamical symmetry limit is extended by adding a 2p-2 h excitation term. Also, the results are compared with the predictions of the partial dynamical symmetry for these levels of considered nuclei. The results show that, this extension removes the degeneracy suggested by the pure SU(3) symmetry and makes satisfactory agreement with the experimental counterparts for the energy levels, too. Also, a comparison between the results of this extended formalism and partial dynamical symmetry shows the advantages of the first one in the description of intruder levels, whereas the latter, makes exact results for the normal energy levels of beta and gamma energy bands. The predictions of pure SU(3), partial dynamical symmetry SU(3) and mixed formalism for different quadrupole transition rates between normal and intruder levels of this nucleus are compared with the predictions of pseudo-SU(3) model and the advantages of each model have explained in detail.

The origin of the neutron skin thickness, measured by the CREX and PREX collaborations as thin for ⁴⁰Ca and thick for ²⁸Pb, remains a mystery. We investigate the effects of tensor and nonlinear isovector–isoscalar terms in a relativistic mean-field model (RMF) on the properties of finite nuclei and nuclear matter. Tensor couplings are crucial for better quality binding energies of finite nuclei and charge radii for relatively heavy nuclei. However, for light nuclei, the tensor terms cannot improve the compatibility of charge radius predictions by the RMF model with experimental data. We find that parameter sets with a larger nonlinear isovector–isoscalar parameter, particularly ${\eta }_{2\rho }$ = 0.028, agree better with experimental data for Δ$r_{np}$ across light, medium, and heavy isotope chains. Using PT28, we calculate Δ$r_{np}$ for ²⁰⁸Pb as 0.214 fm, J as 33.078, and L as 58.426. Δ$r_{np}$ for ²⁰⁸Pb obtained using PT28 is consistent with the PREX-II data. Moreover, the corresponding values of J and L agree with the low L constraints. Meanwhile, the canonical mass radius predicted by PT28 aligns with the mass and radius data from the NICER collaboration. The combination of tensor and nonlinear isovector–isoscalar couplings in the RMF model provides accurate predictions for finite nuclei binding energies and relatively heavy nuclei charge radii, resulting in relatively thick Δ$r_{np}$ values for ²⁰⁸Pb without substantial L values.

To understand the break-up fusion reaction dynamics, the forward recoil range distribution (FRRD) measurements of ¹²C + ¹⁶⁵Ho system at the incident projectile energy of ≈ 88 MeV has been performed. The recoil catcher activation technique followed by the off-line gamma ray spectroscopy was implemented. It is observed that the FRRD measurements of the evaporation residues (ERs) populated via xn and pxn channels have a single Guassian peak at large cumulative thickness. This is attributed to complete momentum transfer from the projectile to the target nucleus. However, in case of the FRRD measurements of the ERs populated via αxn, αpxn and 2αxn emitting channels, in addition to peak corresponding to complete momentum transfer, the Gaussian peaks at lower cumulative thicknesses are also observed. This is accredited to the breakup fusion. Moreover, the effect of projectile breakup on complete fusion cross section is also studied. The suppression in fusion cross section is observed when compared with the universal fusion function, thus indicating the breakup probability of ¹²C projectile.

Large-scale shell-model calculations have been performed for the study of two-neutrino double-beta ($2\nu \beta \beta$) decay in ⁸²Se, ⁹⁴Zr, ¹⁰⁸Cd, ¹²⁴Sn, ¹²⁸Te, ¹³⁰Te, ¹³⁶Xe, and ¹⁵⁰Nd. We have employed JUN45 interaction to calculate the nuclear matrix element (NME) for $2\nu \beta \beta$ decay in ⁸²Se. In the case of ⁹⁴Zr, the glekpn effective interaction is used. For ¹⁰⁸Cd, we have used a realistic effective interaction derived through the G-matrix approach. In the case of ¹²⁴Sn, ^128,130Te and ¹³⁶Xe, the sn100pn effective interaction is employed. For ¹⁵⁰Nd, we have used KHHE effective interaction based on holes in a ²⁰⁸Pb core. We have extracted the half-lives of these nuclei for the $2\nu \beta \beta$ decay with the help of calculated NME. Our results are consistent with the available experimental half-lives. The variation of cumulative $2\nu \beta \beta$ NME with respect to the excitation energy of the intermediate $1^{+}$ states is also shown, and in all cases, it is ensured that their values are almost saturated. In the present work we have calculated more intermediate $1^{+}$ states as much as possible in comparison to results available in the literature.

The values of the parameters ${\rho }^{pp},{\sigma }_{\text{tot}}^{pp}$ and $B^{pp}$ extracted in the region of Coulomb-nuclear interference (CNI) in the ATLAS and TOTEM experiments at energy $\sqrt{s}=13$ TeV are studied based on the general expression for the Coulomb-nuclear amplitude. Due to the significant differences between these data, we undertake both their joint analysis and the retrieval of parameter values separately for each experiment. A significant incompatibility of these parameters published by the ATLAS and TOTEM experiments is shown. This is especially noticeable in the case of ${\sigma }_{\text{tot}}$ and the situation is similar to what once happened at the TEVATRON: the values of ${\sigma }_{\text{tot}}^{ATLAS}$ with account of errors do not overlap with ${\sigma }_{\text{tot}}^{TOTEM}$.