The European Physical Journal A最新文献

The isomeric ratios of (^{198})Au, (^{197})Hg and (^{195})Hg produced by (alpha )-particle induced reactions on natural platinum were investigated experimentally up to 29 MeV by using the standard stacked foil activation technique and (gamma )-ray spectrometry. The isomeric ratios of (^{197})Hg and (^{195})Hg determined by the conventional activation cross section formula showed strong cooling time dependence. The time dependence was resolved by adjusting the isomeric transition branching ratios for the two isotopes within a simultaneous decay curve analysis framework. Our analysis suggests 94.5±0.7% and 48.9±1.8% as the isomeric transition branching ratios of (^{197m})Hg (24 h) and (^{195m})Hg (42 h), respectively. The isomeric ratios and independent production cross sections of (^{198})Au, (^{197})Hg, (^{195})Hg and some other Hg, Au and Pt isotopes were also measured down to 6 MeV with these corrected isomeric transition branching ratios, and compared with predictions of statistical and pre-equilibrium models by TALYS-2.0 to discuss spin cutoff parameter dependence. We found the measured isomeric ratios are better predicted if we reduce the spin cutoff parameter to half or less from that estimated with the rigid body moment of inertia.

The distorted wave Born approximation (DWBA) with a nonlocal deuteron-nucleus d-A potential (Canadian Journal of Physics, 100(6):309–318, 2022) is used to calculate (d, p) transfer cross sections. We considered three target nuclei: light (^{16})O, intermediate (^{40})Ca and heavy (^{208})Pb. For each target nucleus we extracted spectroscopic factors and determined asymptotic normalization coefficients for various values of the single particle radius. The spectroscopic factors are reduced in agreement with previous works in the literature. Compared to the results of DWBA with a local model, the nonlocal model resulted in more peripheral transfer reactions for (^{40})Ca and (^{208})Pb target nuclei, but no significant effect is observed for the light (^{16})O target nucleus. The predicted transfer cross sections are in very good agreement with the experimental data particularly for (^{40})Ca and in the vicinity of the first peak. For the other two target nuclei the predictions of the DWBA with a local model are in slightly better agreement with experiment than the predictions of the nonlocal model at large angles beyond the first peak. For the (^{16})O(d, p)(^{17})O reaction, the fast decrease in the transfer cross section at small forward angles is better predicted by the nonlocal model than the local one. This suggests that the nonlocal model accounts, at least partially, for the channel coupling nonlocality resulting from deuteron break up in the entrance channel.

The present review studies total reaction cross sections from elastic scattering angular distributions of light stable and exotic projectiles ((2 le Z_P le 10), (4 le A_P le 24)) on ²⁰⁸Pb at energies around the Coulomb barrier. From the overall about 200 data it is found that the widely accepted simple grouping of the derived reduced cross sections into three categories—tightly bound, weakly bound, and exotic halo projectiles—is too simplistic and does not fully reflect the range of the experimental data. Furthermore, the energy dependence of the reduced cross sections shows unexpected properties which were hitherto only sparsely considered.

(^{180})Hg is experimentally found to fission asymmetrically. This result was not expected as a naive fragment shell effects study would support the symmetric mode to be the most probable. In the present study we investigate both symmetric and asymmetric (^{180})Hg fission modes at the mean field level using various multipole moment constraints. Potential energy surfaces are analysed in terms of shell effects that shape their topographies and connections to fragment shell effects are made. The non-occurrence of low energy symmetric fission is interpreted in terms of (^{90})Zr fragment properties. Throughout this study a comparison with (^{264})Fm and its symmetric doubly magic (^{132})Sn fission fragments is done.

We present results from an experiment dedicated to measure the lifetimes of the low-lying excited states of ²⁰⁵Bi. This nucleus was studied in the one-proton transfer reaction ²⁰⁴Pb(¹⁶O,¹⁵N)²⁰⁵Bi and the lifetimes of the (11/2^-_1), (7/2^-_1), (5/2^-_1), (7/2^-_2) states were determined by utilizing the Recoil Distance Doppler Shift method. Upon comparing the results with the expectations of the particle-core coupling model, it indicates a low quadrupole collectivity in the structure of these states.

Several refined prompt emission model codes, nowadays employed, use the partition of total excitation energy (TXE) according to the temperature ratio R_T = T_L/T_H of fully accelerated fragments. In such codes R_T is given as input, either as an unique value for all fragmentations or as a function of A_H; This temperature ratio R_T being obtained by fitting the experimental ν(A) data with the respective prompt emission model code. This paper proposes a method for obtaining “experimental R_T(A_H)” (also based on experimental ν(A)), but without resorting to prompt emission model calculations for the fit of ν(A) data. So that this is an independent method providing R_T(A_H) which can be employed by any prompt emission model code in which the TXE partition is done at the full acceleration according to R_T given as input. A procedure which facilitates the parameterization of R_T(A_H) is proposed, too. A prediction of the R_T(A_H) shape at very high excitation energies of the fissioning nucleus is also reported. The comparison of R_T(A_H) ratios obtained from any TXE partition based on modeling at scission with those provided by the present method can constitute a supplementary validation of the respective modeling at scission.

We calculate the spectroscopic parameters of resonance X(4630) observed in the process (B^{+}rightarrow J/Psi phi K^{+}) by at the LHCb experiments at CERN by means of thermal QCD sum rule method at non-zero temperature. The exotic vector X(4630) is assigned as the diquark–antidiquark state ([cs][overline{cs}]) with spin-parity (J^{PC}=1^{-+}). Employing the two-point QCD sum rule approach up to the sixth order of the operator dimension by including non-perturbative contribution, we calculate the mass and decay constant of X(4630) at (Tne 0). The numerical analyses demonstrate that the values of the mass and decay constant of X(4630) near the deconfinement temperature decrease up to (9.8%) and (60%) of their vacuum values. At (Trightarrow 0), the obtained results for the mass (m_{X(4630)}=(4649pm 40)) MeV and decay constant (lambda _{X(4630)}=(10.07pm 0.8)times 10^{-3} ) MeV are in excellent agreement with the results reported by LHCb experiments and other theoretical predictions.

The nuclei lying in the vicinity of the proton drip line are proton emitters. A systematic analysis of the half-life of one proton emitter was estimated using the Effective Liquid Drop Model. We have exploited various mass tables say AME2020, WS4+RBF, FRDM, and KTUY in evaluating the Q-values. The half-lives obtained using various mass tables are compared with experimental values. Among the theoretical mass tables, WS4 is found to have less deviation in the prediction of the half-lives of one proton emission. Alpha-decay half-lives are also estimated to determine which decay mode dominates in the selected isotopes. Geiger–Nutall plots have been plotted and the linear nature of the graph has been successfully reproduced for all the mass tables. The New Geiger–Nuttal law, which illustrates the angular momentum dependency on half-life, also reproduces the linear nature of the graph.

This Topical Collection of the European Physics Journal A is devoted to recent progress in the nuclear many-body problem. In particular, it aims at a comprehensive compilation of developments related to the work of a pioneer in that field, Peter Schuck, who passed away in 2022. Together with Peter Ring, he co-authored the book on “The Nuclear Many-Body Problem”. Different concepts presented in this seminal book have been elaborated further within a broad international collaboration. For instance, the quasi-particle approaches in connection with nuclear superfluidity and cluster formation in nuclear systems, in particular alpha-particle condensation and quartetting at subsaturation densities, have been put forward inspired by Peter Schuck. These advances obtained in the nuclear many-body problem can also be applied to other systems, for instance solid state physics. This Topical Collection is considered as addendum and continuation of the textbook of P. Ring and P. Schuck.

Superfluid dilute neutron matter and ultracold gas, close to the unitary regime, exhibit several similarities. Therefore, to a certain extent, fermionic ultracold gases may serve as emulators of dilute neutron matter, which forms the inner crust of neutron stars and is not directly accessed experimentally. Quantum vortices are one of the most significant properties of neutron superfluid, essential for comprehending neutron stars’ dynamics. The structure and dynamics of quantum vortices as a function of pairing correlations’ strength are being investigated experimentally and theoretically in ultracold gases. Certain aspects of these studies are relevant to neutron stars. We provide an overview of the characteristics of quantum vortices in s-wave-type fermionic and electrically neutral superfluids. The main focus is on the dynamics of fermionic vortices and their intrinsic structure.