Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The isovector giant dipole resonances (IVGDR) in proton-rich Ar and Ca isotopes have been systematically investigated using the resonant continuum Hartree-Fock+BCS (HF+BCS) and quasiparticle random phase approximation (QRPA) methods. The Skyrme SLy5 and density-dependent contact pairing interactions are employed in the calculations. In addition to the giant dipole resonances at energy around 18 MeV, pygmy dipole resonances (PDR) are found to be located in the energy region below 12 MeV. The calculated energy-weighted moments of PDR in nuclei close to the proton drip-line exhaust about 4% of the TRK sum rule. The strengths decrease with increasing mass number in each isotopic chain. The transition densities of the PDR states show that motions of protons and neutrons are in phase in the interiors of nuclei, while the protons give the main contribution at the surface. By analyzing the QRPA amplitudes of proton and neutron 2-quasiparticle configurations for a given low-lying state, we find that only a few proton configurations give significant contributions. They contribute about 95% to the total QRPA amplitudes, which indicates that the collectivity of PDR states is not strong in proton-rich nuclei in the present study.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A model for cold-fusion reactions related to the synthesis of super-heavy nuclei in collisions of heavy projectile-nuclei with a <jats:sup>208</jats:sup>Pb target nucleus is discussed. In the framework of this model, the production of the compound nucleus by two paths, the di-nuclear system path and the fusion path, are taken into account simultaneously. The formation of the compound nucleus in the framework of the di-nuclear system is related to the transfer of nucleons from the light nucleus to the heavy one. The fusion path is linked to the sequential evolution of the nuclear shape from the system of contacting nuclei to the compound nucleus. It is shown that the compound nucleus is mainly formed by the fusion path in cold-fusion reactions. The landscape of the potential energy related to the fusion path is discussed in detail. This landscape for very heavy nucleus-nucleus systems has an intermediate state, which is linked to the formation of both the compound nucleus and the quasi-fission fragments. The decay of the intermediate state is taken into account in the calculation of the compound nucleus production cross sections and the quasi-fission cross sections. The values of the cold-fusion cross sections obtained in the model agree well with the experimental data. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>This investigation aims to find an appropriate dinuclear system for the formation of <jats:inline-formula> <jats:tex-math><?CDATA ${}^{296}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M1.jpg" xlink:type="simple" /> </jats:inline-formula>119 superheavy compound nucleus. By studying the driving potential and measuring the capture cross section of the reactions, the evolution of the dinuclear system can be understood. In this study, we obtained capture, fusion, and evaporation residue cross sections and survival probability at energies near the Coulomb barrier for four reactions, namely <jats:inline-formula> <jats:tex-math><?CDATA $^{45}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M2.jpg" xlink:type="simple" /> </jats:inline-formula>Sc + <jats:inline-formula> <jats:tex-math><?CDATA $^{251}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M3.jpg" xlink:type="simple" /> </jats:inline-formula>Cf, <jats:inline-formula> <jats:tex-math><?CDATA $^{42}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M4.jpg" xlink:type="simple" /> </jats:inline-formula>Ca + <jats:inline-formula> <jats:tex-math><?CDATA $^{254}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M5.jpg" xlink:type="simple" /> </jats:inline-formula>Es, <jats:inline-formula> <jats:tex-math><?CDATA $^{39}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M6.jpg" xlink:type="simple" /> </jats:inline-formula>K + <jats:inline-formula> <jats:tex-math><?CDATA $^{257}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M7.jpg" xlink:type="simple" /> </jats:inline-formula>Fm, and <jats:inline-formula> <jats:tex-math><?CDATA $^{38}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M8.jpg" xlink:type="simple" /> </jats:inline-formula>Ar + <jats:inline-formula> <jats:tex-math><?CDATA $^{258}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M9.jpg" xlink:type="simple" /> </jats:inline-formula>Md. Our calculations show that the reaction <jats:inline-formula> <jats:tex-math><?CDATA $^{38}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M10.jpg" xlink:type="simple" /> </jats:inline-formula>Ar + <jats:inline-formula> <jats:tex-math><?CDATA $^{258}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044107_M11.jpg" xlink:type="simple" /> </jats:inline-formula>Md is a suitable choice for the formation of an element with 119 protons among the studied reactions from a theoretical viewpoint. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>The dependence of proton emission half-lives on the nuclear asymmetry parameter is investigated using the WKB method and two types of empirical formula. Using the single-folding formalism with asymmetry-dependent nuclear radius and surface diffuseness of nuclear matter, the nuclear potential and consequently the half-life are functions of the asymmetry factor. Despite small values of asymmetry in neutron-deficient proton emitters, noticeable changes in the half-lives are observed. The addition of an asymmetry parameter term to the two forms of empirical formulas leads to a reduction in the rms error for ground state and isomeric transitions. A noticeable reduction of about 43% is obtained for isomeric transitions in the second form of the empirical formula. Considering ground state transitions in two categories, odd-even and odd-odd emitters, and adopting deformation and asymmetry-dependent empirical formulas, the rms decreases remarkably. The lowest values of rms errors, viz. 0.1492, 0.2312, and 0.1999, are obtained for the aforementioned empirical formulas for ground state transitions of odd-even and odd-odd emitters and for all isomeric transitions, respectively.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Transport models cannot simultaneously explain very recent data on pion multiplicities and pion charged ratios from central collision of Sn+Sn at 0.27 <jats:italic>A</jats:italic> GeV. This stimulates further investigations on the pion dispersion relation, in-medium <jats:inline-formula> <jats:tex-math><?CDATA $N\pi\to \Delta$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044109_M2.jpg" xlink:type="simple" /> </jats:inline-formula> cross sections, and <jats:inline-formula> <jats:tex-math><?CDATA $\Delta \to N \pi$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044109_M3.jpg" xlink:type="simple" /> </jats:inline-formula> decay widths near the threshold energy or at subthreshold energy of pion production in isospin asymmetric nuclear matter. In this study, the pion dispersion relation, in-medium <jats:inline-formula> <jats:tex-math><?CDATA $N\pi\to \Delta$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044109_M4.jpg" xlink:type="simple" /> </jats:inline-formula> cross section, and <jats:inline-formula> <jats:tex-math><?CDATA $\Delta \to N \pi$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044109_M5.jpg" xlink:type="simple" /> </jats:inline-formula> decay width near the threshold energy are investigated in isospin asymmetric nuclear matter by using the one-boson-exchange model. With the consideration of the energy conservation effect, the in-medium <jats:inline-formula> <jats:tex-math><?CDATA $N\pi\to\Delta$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044109_M6.jpg" xlink:type="simple" /> </jats:inline-formula> cross sections are enhanced at <jats:inline-formula> <jats:tex-math><?CDATA $s^{1/2}\lt 1.11$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044109_M7.jpg" xlink:type="simple" /> </jats:inline-formula> GeV in a nuclear medium. The prediction of pion multiplicity and <jats:inline-formula> <jats:tex-math><?CDATA $\pi^-/\pi^+$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044109_M8.jpg" xlink:type="simple" /> </jats:inline-formula> ratios near the threshold energy could be modified if this effect is considered in transport model simulations. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this study, based on the Gamow-like model, we systematically analyze two-proton ( <jats:inline-formula> <jats:tex-math><?CDATA $2p$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044110_M1.jpg" xlink:type="simple" /> </jats:inline-formula>) radioactivity half-lives of nuclei near or beyond the proton drip line. It is found that the calculated results can reproduce experimental data well. Furthermore, using this model, we predict the half-lives of possible <jats:inline-formula> <jats:tex-math><?CDATA $2p$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044110_M2.jpg" xlink:type="simple" /> </jats:inline-formula> radioactivity candidates whose <jats:inline-formula> <jats:tex-math><?CDATA $2p$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044110_M3.jpg" xlink:type="simple" /> </jats:inline-formula> radioactivity is energetically allowed or observed but not yet quantified in the latest table of evaluated nuclear properties, i.e., NUBASE2016. The predicted results are in good agreement with those from other theoretical models and empirical formulas, namely the effective liquid drop model (ELDM), generalized liquid drop model (GLDM), Sreeja formula, and Liu formula. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>An improved semi-empirical relationship for cluster radioactivity half-lives is proposed by introducing an accurate charge radius formula and an analytic expression of the preformation probability. Moreover, the cluster radioactivity half-lives for the daughter nuclei around <jats:sup>208</jats:sup>Pb or its neighbors and the <jats:sup>12</jats:sup>C radioactivity half-life of <jats:sup>114</jats:sup>Ba are calculated within the improved semi-empirical relationship. It is shown that the accuracy of the new relationship is improved significantly compared to its predecessor. In addition, the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead and trans-tin nuclei are predicted by the new semi-empirical formula. These predictions might be useful for searching for the new cluster emitters of the two islands in future experiments. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>Correlations of conserved charges, i.e., the baryon number, electric charge, and strangeness, are calculated at finite temperature and chemical potentials up to the fourth order. The calculations are done in a 2+1 flavor low energy effective theory, in which the quantum and thermal fluctuations are encoded through the evolution of flow equations within the functional renormalization group approach. Strangeness neutrality and a fixed ratio of the electric charge to the baryon number density are implemented throughout the computation. We find that higher-order correlations incorporate more sensitive critical dynamics than the quadratic ones. In addition, a non-monotonic dependence of the fourth-order correlations between the baryon number and strangeness, i.e., <jats:inline-formula> <jats:tex-math><?CDATA $ -\chi^{BS}_{31}/\chi^{S}_{2}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044112_M1.jpg" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math><?CDATA $ \chi^{BS}_{22}/\chi^{S}_{2}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044112_M2.jpg" xlink:type="simple" /> </jats:inline-formula>, on the collision energy is also observed. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>The current-mode-counting method is a new approach to observing transient processes, especially in transient nuclear fusion, based on the non-homogeneous Poisson process (NHPP) model. In this paper, a new measurement process model of the pulsed radiation field produced by transient nuclear fusion is built based on the NHPP. A simulated measurement is performed using the model, and the current signal from the detector is obtained by simulation based on Poisson process thinning. The neutron time spectrum is reconstructed and is in good agreement with the theoretical value, with its maximum error of a characteristic parameter less than 2.3%. Verification experiments were carried out on a CPNG-6 device at the China Institute of Atomic Energy, with a detection system with a nanosecond response time. The experimental charge amplitude spectra are in good agreement with those obtained by the traditional counting mode, and the characteristic parameters of the time spectrum are in good agreement with the theoretical values. This shows that the current-mode-counting method is effective for the observation of transient nuclear fusion processes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Direct detection experiments tend to lose sensitivity in searches for sub-MeV light dark matter candidates due to the threshold of recoil energy. However, such light dark matter particles could be accelerated by energetic cosmic rays, such that they could be detected with existing detectors. We derive constraints on the scattering of a boosted light dark matter particle and electron from the XENON100/1T experiment. We illustrate that the energy dependence of the cross section plays a crucial role in improving both the detection sensitivity and also the complementarity of direct detection and other experiments.</jats:p>