Nuclear Physics A最新文献

The configurations of terminating bands in Er isotopes are investigated using the unpaired cranked Nilsson-Strutinsky (CNS), and the paired cranked Nilsson-Strutinsky-Bogoliubov (CNSB) models and also, new CNS(B) formalism. The calculated excitation energies of the bands have been compared with the experimental findings, and good agreements are observed. Our calculations show that the CNS(B) approach successfully is in agreement CNSB predictions and experimental results. Some systematics of terminating bands in erbium isotopes are also discussed.

We have conducted a comprehensive and systematic study of the proton radioactivity and α-decay half-lives of neutron-deficient nuclei. This investigation involved the utilization of various Proximity potentials and also considered the incorporation of thermal effects. For the half-life calculations, we employed both temperature-independent and temperature-dependent interaction potentials. We observed that proton radioactivity serves as the dominant mode of decay for nuclides situated very close to the proton drip-line. We explored a universal curve that examines the correlation between the decimal logarithm of experimental half-lives and the negative decimal logarithm of the penetrability for both proton radioactivity and α-decay.

Strange particles are produced only during high-energy collisions and carry important information regarding collision dynamics. Recent results by the ALICE Collaboration on strangeness enhancement in high-multiplicity p+p collisions have highlighted the importance of the rope hadronization mechanism in high-energy nucleon-nucleon collisions. With the help of the PYTHIA8 model, we made an attempt to study the strange particle production in high-energy p+p collisions at the LHC energy in the light of different color reconnection models and rope hadronization mechanism. The effect of color reconnection ranges on different observables is also discussed. The integrated yield of strange hadrons and baryon-to-meson ratios as a function of charged-particle multiplicity in p+p collisions at $\sqrt{s}$ = 13 TeV are well described by the hadronization mechanism of color ropes together with the QCD-based color reconnection scheme. The increasing trend of the average transverse momentum, $〈p_T〉$, as a function of ${〈dN/d\eta 〉}_{\left|\eta \right|<0.5}$ can be explained quantitatively by the MPI-based color reconnection mechanism with a reconnection range of RR = 3.6; on the other hand, it is underestimated by the rope hadronization model.

Various decay modes in superheavy nuclei have been of significant interest among which cluster radioactivity has recently gained sizable attention. The α-decay being a predominant decay mode in the superheavy region, the accurate determination of cluster decay half-lives is also crucial in this region as it has tremendous potential to be explored as one of the major decay channels. The usability of the Royer analytical formula [Nuclear Physics A 683 (2001) 182], which is based on the asymmetric fission model, has been investigated for the cluster and α-decay in superheavy region, by comparing it with several other (semi)empirical/analytical formulas. After fitting the formula on around 100 cluster-decay data and around 423 α-decay data, the refitted Royer formula (RRF) is found to be very robust which is able to estimate the cluster decay and α-decay half-lives with good accuracy. In fact, a comparison of the half-lives of both the decay modes using the same formula points towards a substantial chance of heavy cluster (Kr and Sr) decay from various isotopes of Z=118 and 120. Hence, the formula proposed in this study works fairly well for the estimation of cluster decay half-lives in superheavy regions where most empirical formulas fail to match with the half-lives from the various established theories.

This report presents experimental differential cross section measurements at α_0-particles’ eight outgoing angles of 50°, 70°, 90°, 106°, 120°, 130°, 150°, and 160° from ¹¹B(p, α₀)⁸Be reaction induced by 2.5 MeV proton beam bombarding on a natural boron target. The proton beams were accelerated by the 5SDH-2 pelletron at the University of Science - Hanoi National University (HUS). A good agreement has been observed between the obtained results and those from the literature. The importance of the data in a widely angular range is evidenced for the precise determination of the total integrated cross section.

We have constructed the empirical formula for fusion barrier height ($V_B$), fusion barrier position ($R_B$), and inverted parabola (ħω) of light nuclei with atomic number in the range 2$\le Z_C\le$10. This formula is obtained by studying the fusion barrier characteristics of 333 projectile target combinations. The values produced by the present formula are also compared with experiments. The present semi-empirical formula produces fusion barrier characteristics of light nuclei with the simple inputs of mass number (A) and atomic number (Z) of projectile targets. This semi-empirical formula can be utilized to calculate and interpret fusion barrier characteristics in light nuclear systems.

In the present work we have analyzed the transverse momentum spectra of charged particles in high multiplicity pp collisions at LHC energies $\sqrt{s}=5.02$ and 13 TeV published by the ALICE Collaboration using the Color String Percolation Model. For heavy ions Pb-Pb at $\sqrt{s_{NN}}=2.76$ and 5.02 TeV along with Xe-Xe at $\sqrt{s_{NN}}=5.44$ TeV have been analyzed. The initial temperature is extracted both in low and high multiplicity events in pp collisions. For $A-A$ collisions the temperature is obtained as a function of centrality. A universal scaling in the temperature from pp and $A-A$ collisions is obtained when multiplicity is scaled by the transverse interaction area. From the measured energy density ε and the temperature the dimensionless quantity $\epsilon /T^4$ is obtained. Our results for Pb-Pb and Xe-Xe collisions show a sharp increase in $\epsilon /T^4$ above T ∼ 210 MeV and reaching the ideal gas of quarks and gluons value of $\epsilon /T^4\sim 16$ at temperature ∼230 MeV.

In order to investigate the contribution of α production in the reaction cross sections, measurements of elastic scattering and inclusive α particle angular distributions have been carried out with the ⁹Be projectile on ⁸⁹Y, ¹²⁴Sn, ¹⁵⁹Tb, ¹⁹⁸Pt, and ²⁰⁹Bi targets over a wide angular range at energies near the Coulomb barrier. The measured elastic scattering angular distributions were fitted with optical model calculations, and reaction cross sections were extracted. The same data were also analyzed using both global optical model potentials (Global OMP) and microscopic São Paulo potentials (SPP), to obtain the reaction cross sections. The data available in the literature for ⁹Be projectile includes the elastic scattering angular distributions, α production cross sections, and complete fusion cross sections on these and other targets at several energies are also utilized for comparative studies. The reaction cross section extracted from the three potentials (Best Fit, Global OMP and SPP) are in reasonable agreement for all the targets except for the energies below the barrier where the results from SPP deviate by 30-50%. Inclusive α particle production cross sections were also extracted by integrating the α particle angular distributions. The present data and data available from literature of reaction and α-particle production cross sections were utilized to make systematic studies. Systematics of reaction and α-particle production cross sections revealed their universal behavior. The ratio of complete fusion (CF), inclusive α cross sections, and their sum (CF+α) to reaction cross sections show that at sub-barrier energies inclusive α dominates and above barrier CF dominates, and cumulative of these two processes almost explains the reaction cross section at all energies over a wide range of target mass. A comparative study of α production with other weakly bound projectiles is also performed and a clear distinction between projectile types is observed, which is found to correlate well with α separation energies of the projectiles.

The mean total kinetic energy as a function of fission fragments, <TKE>(A), is calculated for neutron-induced fission of ^{247,249,251,253,255}Cf, as well as for spontaneous fission of ^{248,250,252,254}Cf using the scission point model. A comparative analysis is performed between the calculated results and existing experimental data. Investigation into the behavior of <TKE>(A) is conducted, particularly focusing on intermediate and heavy actinides. While nuclear and Coulomb energy evaluations suffice for estimating <TKE> values in light actinides, this approximation proves inadequate for evaluating TKE values for intermediate and heavy actinides. Additionally, an evaluation is made of the total excitation energy as a function of fission fragments, <TXE>(A), concerning spontaneous fission in ^247−254Cf. It is found that TXE values sharply increase near the symmetric region across all isotopes and exhibit a gradual increase in heavy fission fragments. Furthermore, an exploration of the total neutron multiplicity as a function of fission fragments, ${\nu }_T\left(A\right)$, is conducted for ²⁵²Cf fission using two methods. The ${\nu }_T\left(A\right)$ results obtained through these methods are compared with experimental data, and ${\nu }_T\left(A\right)$ is estimated for unmeasured californium isotopes. The average neutron emission per fission event, $\overline{\nu }\left(A_i\right)$, is then calculated for spontaneous fission of ²⁵¹Cf and ²⁵³Cf, yielding values of 3.46 and 3.59, respectively.

In the present work, beta-decay properties such as $\log ft$ values and half-lives have been systematically studied corresponding to Ba isotopes using large-scale shell-model calculations. An extensive comparison of beta decay results corresponding to ¹⁴¹Ba → ¹⁴¹La using shell-model calculations is made with the recently available experimental data. In addition, we have also calculated the nuclear and beta decay properties corresponding to ¹³⁹Ba → ¹³⁹La and ¹⁴⁰Ba → ¹⁴⁰La transitions. The model-space considered here is $Z=50-82$ and $N=82-126$ with ¹³²Sn core, and the interaction employed here is jj56pnb interaction. The beta decay results using shell-model calculations for all the mentioned isotopes are compared with the available experimental data. This is the first theoretical interpretation corresponding to recent experimental data.