Global density-dependent α\alpha-nucleon interaction for α\alpha-nucleus elastic scattering

We provide a global density-dependent $^4$He-nucleon (DD-$\alpha N$) interaction to construct the $\alpha$-nucleus optical model potential (OMP) in a wide range of incident energies. The global parametrization for the DD-$\alpha N$ interaction is obtained based on the proton-$^4$He OMP which reproduces the elastic scattering cross-section data very well in the incident energies of 12.04--500 MeV per nucleon. We derive the $\alpha$-nucleus potential by a folding procedure with the point-nucleon density obtained by a microscopic mean-field model using the present DD-$\alpha N$ interaction. The density dependence of the DD-$\alpha N$ interaction is fixed phenomenologically to reproduce the $\alpha$-nucleus elastic scattering cross-section data by the $^{16}$O, $^{40}$Ca, $^{58}$Ni, $^{90}$Zr, and $^{208}$Pb targets at $E/A =$ 10--342.5 MeV. We also show the total reaction cross sections, which are helpful in fixing one free parameter, the renormalization factor for the imaginary part of the $\alpha$-nucleus potential. Lastly, we show some examples, which clearly demonstrate the validity and power of the present DD-$\alpha N$ approach.Comment: 20 pages, 11 figure

Global optical potential for nucleus-nucleus systems from 50 MeV/u to 400 MeV/u

We present a new global optical potential (GOP) for nucleus-nucleus systems, including neutron-rich and proton-rich isotopes, in the energy range of $50 \sim 400$ MeV/u. The GOP is derived from the microscopic folding model with the complex $G$-matrix interaction CEG07 and the global density presented by S{\~ a}o Paulo group. The folding model well accounts for realistic complex optical potentials of nucleus-nucleus systems and reproduces the existing elastic scattering data for stable heavy-ion projectiles at incident energies above 50 MeV/u. We then calculate the folding-model potentials (FMPs) for projectiles of even-even isotopes, $^{8-22}$C, $^{12-24}$O, $^{16-38}$Ne, $^{20-40}$Mg, $^{22-48}$Si, $^{26-52}$S, $^{30-62}$Ar, and $^{34-70}$Ca, scattered by stable target nuclei of $^{12}$C, $^{16}$O, $^{28}$Si, $^{40}$Ca $^{58}$Ni, $^{90}$Zr, $^{120}$Sn, and $^{208}$Pb at the incident energy of 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 250, 300, 350, and 400 MeV/u. The calculated FMP is represented, with a sufficient accuracy, by a linear combination of 10-range Gaussian functions. The expansion coefficients depend on the incident energy, the projectile and target mass numbers and the projectile atomic number, while the range parameters are taken to depend only on the projectile and target mass numbers. The adequate mass region of the present GOP by the global density is inspected in comparison with FMP by realistic density. The full set of the range parameters and the coefficients for all the projectile-target combinations at each incident energy are provided on a permanent open-access website together with a Fortran program for calculating the microscopic-basis GOP (MGOP) for a desired projectile nucleus by the spline interpolation over the incident energy and the target mass number.Comment: 25 pages, 13 figure

Hydrodynamic and Mass Transfer Properties in a Three Phase External Loop Airlift Compared with a Three Phase Internal Loop Airlift and a Slurry Bubble Column

The effects of suspended solid particles on the hydrodynamic and mass transfer properties were experimentally studied in a wide range of the superficial gas velocity, solid particle property and liquid viscosity in an external loop airlift bubble column in comparison with those in an internal loop airlift bubble column as well as a normal bubble column. The circulating liquid velocities UL, gas holdups G and volumetric gas liquid oxygen transfer coefficients kLa in the riser of the external loop airlift were found to be almost unaffected by the completely suspended solid particles. The above three properties obtained could be represented by our previous correlations for the gas-liquid two phase flow within an accuracy of ± 30% for a practical reactor design and operation. The analogous results were obtained on the G and kLa data in the three phase normal and internal loop airlift bubble columns, although a small amount of suspended solid particles was observed to cause a slight decrease in these values in contrast to a lower or negligible decrease in those of the three phase external loop airlift

Gas-Liquid Interfacial Area, Bubble Size and Liquid-Phase Mass Transfer Coefficient in a Three-Phase External Loop Airlift Bubble Column

The interfacial area a was measured by the sulfite oxidation method in a three-phase external loop airlift bubble column suspending completely the different concentrations of ion exchange resin particles in aqueous carboxymethyl cellulose (CMC) solutions with a wide range of viscosity. The column had been previously studied for the circulating liquid velocity UL, gas holdup G and volumetric gas-liquid oxygen transfer coefficient kLa in the two- and three-phase systems. The average bubble size dB and oxygen transfer coefficient kL were obtained as dB = 6 G/a and kL = (the previous kLa)/a, respectively. The similar studies were carried out in the internal loop airlift and normal bubble columns for comparison. The a values in the external loop airlift were found to be little affected by the column height and particles concentrations, and to decrease with increasing viscosity. All the three columns showed a linear dependence of a on G. A simple correlation of a, dB or kL was proposed as a function of G and viscosity for the external loop airlift as well as both internal loop airlift and normal columns. A well-known relationship between kL and dB was confirmed to hold independent of column types and operating conditions for a given two or three phase system

In-beam γ-ray spectroscopy of 136Te at relativistic energies

The reduced transition probability B(E2; 0+ 1 →2+ 1 ) to the first excited 2+ state of the neutron-rich nucleus 136Te, with two protons and two neutrons outside the doubly magic 132Sn core, was measured via Coulomb excitation at relativistic energies at the RIKEN Radioactive Isotope Beam Factory. A value of B(E2)= 0.191(26) e2b2 was extracted from the measured inelastic scattering cross section on an Au target taking into account the contributions from both Coulomb and nuclear excitations. In addition, an upper limit for the transition strength to a 2+ state of mixed-symmetry character in the excitation energy range of 1.5–2.2 MeV was determined and compared to the predictions of various theoretical calculations. Because of the high statistics gathered in the present experiment the error of the deduced B(E2) value is dominated by the systematic uncertainties involved in the analysis of Coulomb excitation experiments at beam energies around 150 MeV/u. Therefore, the latter are for the first time assessed in detail in the present work.Spanish Ministerio de Economía y Competitividad (FPA2014-57196-C5-4-P, FPA2017-84756-C4-2-P, FIS2014-53448-C2-1-P