The European Physical Journal A最新文献

Closed expressions for the masses of the charged and neutral pions are derived based on a simple approximate model for electrostatic screening when a proton is located adjacent to a neutron. The estimated mass values agree to a few percent of experimentally measured values. The electric dipole moment of the deuteron is also estimated based on the phenomenological toy model used here.

The fission yields of mercury isotopes were calculated and evaluated by using the improved scission point model. The asymmetric fission of ¹⁸⁰Hg was analyzed within the framework of the scission point model with octupole deformed fragments. The fission mass asymmetry of ¹⁸⁰Hg is attributed to the influence of N = 44, 56 and Z = 34, 46 shell gaps for octupole deformations and the liquid drop model. The evolution of proton and neutron numbers in asymmetric fragments of mercury isotopes is also explained by octupole deformed shell gaps.

Here we aim to examine the fusion dynamics and explore the influence of the proton halo structure on above and below barrier fusion cross sections for reactions induced by ⁸B on ²⁸Si, ⁵⁸Ni, ¹⁴⁴Sm and ²⁰⁸Pb targets. The calculations have been carried out by Continuum discretised coupled channel (CDCC) approach-based computer code FRESCO. It is found that on inclusion of continuum couplings, the total (TF) and complete fusion (CF) calculations are affected insignificantly for light and heavier mass targets with respect to the predictions of Universal fusion function (UFF) curve and without coupling calculations. While a significant variation in both TF and CF has been observed for medium mass target. Further, in present work it has also been noticed that the calculated suppression factor for proton-halo does not follow a systematic trend of other neutron-halo or stable (weakly or tightly bound) projectile.

The absorbing boundary conditions method is applied in the microscopic Bloch–Brink cluster model using the generator coordinate method to study the resonance states of (^8textrm{Be}). A complex absorbing potential is introduced into the Hamiltonian, equivalent to the absorbing kernels added to the Hill-Wheeler equation. The (0^{+}), (2^{+}), and (4^{+}) states of (^{8}textrm{Be}) are analyzed for their corresponding energies and widths. The obtained results are consistent with those of the algebraic version of the resonating group method. This work is helpful in demonstrating the efficiency of the absorbing boundary conditions method for addressing nuclear cluster resonance problems within the framework of the generator coordinate method.

Excited states above the (9^+) isomer in the odd-odd N = Z nucleus (^{66})As were studied by employing the (^{40})Ca((^{28})Si, pn) fusion-evaporation reaction at the Accelerator Laboratory of the University of Jyväskylä, Finland. A key method in this study was the use of conversion electrons emitted in the de-excitation of the isomeric state in (^{66})As as a tag for prompt (gamma ) rays. Several new states have been added to the (^{66})As level scheme, which was extended up to a tentative spin of 23(hbar ). The previously reported even-spin yrast band has been reassigned to have odd spin values. The odd-spin states above the (9^+) isomer are compared with shell-model calculations using the jj44b and JUN45 interactions. Additionally, the recoil-(beta ) tagging efficiency of the recently developed scintillator detector named Tuike has been determined experimentally for the first time.

The possibility of wobbling mode in the A (approx ) 80 mass region is investigated by using the constrained triaxial covariant density functional theory and quantum particle rotor model for rubidium isotopes. Several states with the obvious triaxial deformation and high-j particle configuration are obtained in (^{79,81,83,85})Rb, which are suitable for establishing the wobbling mode. Taking the nucleus (^{81})Rb as an example, the available experimental energy spectrum with the (pi )g(_{9/2}) configuration is described well. The decreased energy difference between the partner bands, the enhanced (B(E2)_{out})/(B(E2)_{in}) values, the angular momentum components and the azimuthal plots indicate that (^{81})Rb can be transverse wobbling candidate. The present work provides a promising basis for future experimental research on the wobbling mode in the A (approx ) 80 mass region.

Inclusive spectra of the kaons produced in ArSc collisions as functions of their transverse momentum (p_T) at mid-rapidity have been calculated within the approach based on the assumption of the similarity of inclusive spectra of the hadrons produced in nucleus–nucleus collisions at their small transverse momenta in the mid-rapidity region taking into account the quark-gluon dynamics in nucleon–nucleon interactions. This article gives a satisfactory description of NA61/SHINE data on (p_T)-spectra of the (K^pm ) mesons produced in ArSc collisions at the mid-rapidity ((ysimeq ) 0).

The even-odd staggering in fission fragments yield distributions is an important observable to address the role of intrinsic excitations in the fission process. However, its computation as a function of the fragment split is an ill-posed problem that is usually solved through certain assumptions. Arguably, the most widely used method for its computation is the log-third-difference method, which assumes an underlying local Gaussian distribution. Experimental data of the even-odd effect show sharp features and peaks that are a challenge for the log-third difference method (or any method for that matter). This paper presents a detailed study of the performance of the log-third-difference method and describes three strategies for improving the precision and accuracy around these sharp features. The best results are obtained with an iterative application of the method and with the use of a multi-Gaussian fit. A hybrid process combining both corrections is also described and applied to real data. In regions with a smooth behaviour, the direct application of the log-third-difference method remains the best option.

The radiation damage of 21 (upmu )m thick self-biased epitaxial (varDelta E) detectors were tested as a function of fluence of 90 MeV (^{14})N ions. Technology of production and technique of measurements of (varDelta E) detectors were described. A new technique of soldering contact to thin detector is shown. In the present work the 21 (upmu )m thick self-biased detectors marked as d4 and d5 show proper operation with the fluence about 4(cdot )10(^{15}) (hbox {ions/cm}^{2}) and the fluence about 8(cdot )10(^{15}) (hbox {ions/cm}^{2}), respectively. The charge collection efficiency of thin d5 (varDelta E) detector was increased about double at fluence about 8(cdot )10(^{15}) (hbox {ions/cm}^{2}). The charge collection efficiency of thin d4 (varDelta E) detector was increased about 35(%) at fluence about 4(cdot )10(^{15}) (hbox {ions/cm}^{2}) followed decrease about 70(%) of detector counting rate registration from fluence 9.1(cdot )10(^{15}) (hbox {ions/cm}^{2}) to fluence about 5(cdot )10(^{16}) (hbox {ions/cm}^{2}) due to partially removing of Al evaporated contact from detector surface as an effect of heavy ion irradiation. Increase of charge collection efficiency of thin self-biased detectors manufactured by the low-temperature technique was probably produced by increasing of build-in potential as an effect of activate carrier concentration of boron ions in epitaxial layer by heavy ion irradiation.