Nuclear Physics A最新文献

An improved Gamow-like (IMGL) formula for cluster radioactivity half-lives is proposed by introducing an accurate charge radius formula, an analytic expression of assault frequency, the angular momentum carried by the emitted cluster and the isospin effect. By using the IMGL formula, the cluster radioactivity half-lives of 20 nuclei are calculated. It is shown that the IMGL formula improves the agreement with experimental data compared to its predecessor. Then, several sets of other semi-empirical formulas, including the Ni-Ren-Dong-Xu (NRDX), universal decay law (UDL), Tavares-Medeiros (TM), Balasubramaniam-Kumarasamy-Arunachalam-Gupta (BKAG), Viola-Seaborg-Sobiczewski (VSS) and extended universal decay law (EUDL) formulas, are used to calculate the half-lives of cluster radioactivity. By comparing the agreement between the half-lives extracted from different semi-empirical formulas and the experimental data, it is found that the IMGL formula is more accurate than others. At last, within the IMGL formula the cluster radioactivity half-lives of Z=85-97 isotopes that are not available experimentally are predicted. It might be helpful for searching for the new cluster emitters in future measurements.

Observable properties of neutron stars are studied within a hadronic equation of state derived from the quark level. The effect of short-range repulsion is incorporated within the excluded volume framework. It is found that one can sustain neutron stars with masses as large as 2.2$M_{\odot }$ even including hyperons in β equilibrium, while producing radii and tidal deformabilities consistent with current constraints.

By employing the nonlinear Regge trajectory relation $M=m_R+{\beta }_x{(x+c_{0x})}^{2/3}(x=l,n_r)$, we investigate the heavy-heavy systems, such as the doubly heavy diquarks, the doubly heavy mesons, the heavy-heavy baryons, and the heavy-heavy tetraquarks. The fitted Regge trajectories illustrate that these heavy-heavy systems satisfy the above formula and show the existence of an universal description of the heavy-heavy systems. The universality embodies not only the universal behavior $M\sim x^{2/3}$ but also the universal parameters. The values of $c_{f{n}_r}$ and $c_{fl}$ vary with different heavy-heavy systems, but they are close to one. There is an inequality ${\beta }_{n_r}>{\beta }_l$, and it holds for all the discussed heavy-heavy systems. Moreover, the expression of ${\beta }_x$ [Eq. (11)] explains its variation with the change of the constituents' masses.

The observed asymmetric fission of the ¹⁸⁰Hg^⁎ compound nucleus challenges conventional expectations of symmetric fission, which are attributed to the presence of shell closures at Z=40 (semi-magic) and N=50 (magic). To comprehend this novel phenomenon, the dynamical cluster-decay model has been employed. For the first time, this model incorporates the bulk and neutron-proton asymmetry coefficients of the nuclear shape-dependent mass excess formula which are tuned recently to the ground state mass excess data of AME2020 and/or FRDM(2012) along with the temperature dependence for the nuclear shape and the surface energy coefficient of the nuclear proximity potential. The calculations have considered nuclear shapes as both spherical and deformed (quadrupole), with and without temperature dependence for the quadrupole deformation. A new minimum appears in the symmetric mass region of the fragmentation potential for masses (80, 100), when the fragments are deformed and optimally oriented, at an energy lower than that obtained for masses (90, 90) where the fragments are assumed to be spherical or nearly spherical at higher temperatures. This new minimum seems equivalent to the appearance of a new shell gap with deformation and is responsible for the asymmetric fission of ¹⁸⁰Hg^⁎. The most probable fission channel and the transition from asymmetric to symmetric mass distribution at higher excitation energies are consistent with experiments for the current temperature dependence assigned to the quadrupole deformation parameter.

We generalize and extend the recently proposed method [1] to account for contributions of system size (or volume/participant) fluctuations to the experimentally measured moments of particle multiplicity distributions. We find that in the general case there are additional biases which are not directly accessible to experiment. These biases are, however, parametrically suppressed if the multiplicity of the particles of interest is small compared to the total charged-particle multiplicity, e.g., in the case of proton number fluctuations at top RHIC and LHC energies. They are also small if the multiplicity distribution of charged particles per wounded nucleon is close to the Poissonian limit, which is the case at low energy nuclear collisions, e.g., at GSI/SIS18. We further find that mixed events are not necessarily needed to extract the correction for volume fluctuations. We provide the formulas to correct pure and mixed cumulants of particle multiplicity distributions up to any order together with their associated biases.

In this work, the production of $\gamma p\to \varphi \left(2170\right)p$ is studied for the first time by using the two gluon exchange model and effective Pomeron exchange model under the assumption that ϕ(2170) is a conventional $s\overline{s}$ state. On the whole, the numerical results show that the total cross section of $\varphi \left(2170\right)$ through γp scattering can reach more than 70 nb at a center-of-mass energy of W=7 GeV. A comparison between the outcomes of the two models reveals subtle discrepancies. Moreover, base on the cross section of $\varphi \left(2170\right)$ photoproduction, we systematically analyzed the production of $\varphi \left(2170\right)$ at Ultra-Peripheral Collisions (UPCs) and Electron-Ion Colliders (EICs) by using the STARlight and eSTARlight program developed by Brookhaven National Laboratory (BNL). Accordingly, the cross section, event number and rapidity distribution of $\varphi \left(2170\right)$ through EICs and UPCs are predicted based on the accelerator experiments. These projections offer valuable theoretical insights for forthcoming experiments at EicC, EIC-US, RHIC, and LHC facilities.

The stochastic mean-field (SMF) approach beyond the time-dependent-Hartree-Fock theory is used to explore the primary production cross sections in ${}^{64}\text{Ni}+{}^{130}\text{Te}$ at the bombarding energy $E_{\text{c.m.}}=184.3$ MeV and ${}^{206}\text{Pb}+{}^{118}\text{Sn}$ at $E_{\text{c.m.}}=436.8$ MeV. Secondary production cross-sections in the same systems are calculated using a statistical de-excitation model with GEMINI++ code. The obtained results are compared with available experimental data. Analysis employing SMF and GEMINI++ exhibit a good agreement with the experimental data.

Natural silver targets were irradiated using an alpha particle beam to measure the activation cross sections of radioisotopes within the energy range of 23–40 MeV. The newly obtained cross section data, compared with previous experimental results, underline the importance of this work in the context of nuclear reactions and medical applications. Alpha particle induced reaction with ${}^{nat}$Ag involved the production of radioisotopes such as ¹¹¹In, ¹⁰⁵Ag, ${}^{106m}$Ag. In this study, we focused on calculating correlation matrices for the ${}^{nat}$Ag(α,x) nuclear reactions. These matrices were generated by considering various interconnected variables, such as decay constants, particle number densities, γ-ray intensities and detector efficiencies for both monitor and sample nuclear reaction products.

Parts 3 and 4 of the original Abstract have been modified as:

3. I use these new values of the $D=6,8$ power corrections to extract ${\alpha }_s$ from the BNP lowest moment. To order ${\alpha }_s^4$, I find within the SVZ expansion: ${\alpha }_s\left(M_{\tau }\right){|}_{e^{+}{e}^{-}}^{SVZ}=0.3081{\left(49\right)}_{fit}{\left(71\right)}_{{\alpha }_s^5}$ [resp. $0.3260{\left(47\right)}_{fit}{\left(62\right)}_{{\alpha }_s^5}]$ implying ${\alpha }_s\left(M_Z\right){|}_{e^{+}{e}^{-}}^{SVZ}=0.1170\left(6\right){\left(3\right)}_{evol}$ [resp. $0.1192\left(6\right){\left(3\right)}_{evol}$] for Fixed Order (FO) [resp. Contour Improved (CI)] PT series. They lead to the mean: ${\alpha }_s\left(M_{\tau }\right){|}_{e^{+}{e}^{-}}^{SVZ}=0.3179{\left(58\right)}_{fit}{\left(81\right)}_{syst}$ and