Phenomenological Scaling of Rapidity Dependence for Anisotropic Flows in 25 MeV/nucleon Ca + Ca by Quantum Molecular Dynamics Model

Anisotropic flows ($v_1$, $v_2$, $v_3$ and $v_4$) of light fragments up till the mass number 4 as a function of rapidity have been studied for 25 MeV/nucleon $^{40}$Ca + $^{40}$Ca at large impact parameters by Quantum Molecular Dynamics model. A phenomenological scaling behavior of rapidity dependent flow parameters $v_n$ (n = 1, 2, 3 and 4) has been found as a function of mass number plus a constant term, which may arise from the interplay of collective and random motions. In addition, $v_4/{v_2}^2$ keeps almost independent of rapidity and remains a rough constant of 1/2 for all light fragments.Comment: 4 pages, 5 figure

Application of Poly (vinylbutyral) Nanocomposites in Environment Design

This text passed an adoption to totally mix a method to lead to make even PVB/SiO2 compound material into the nano SiO2 grain son in gather the PVB material.. With the UV-VIS, FT-IR, XRD, SEM etc. modern tested means token tiny view facial look, structure and optics function of material. Result enunciation:because the lead of the nano SiO2 grain son go into and make the compound material of the PVB/SiO2 have good ultraviolet rays to shield function; Meanwhile, the tenacity of material gets an obvious exaltation, it splits an elongation rate is 8 times than the for pure PVB material. Key words: nanocomposite; mixing process; nanometer silica; environment desig

Scaling of Anisotropic Flows and Nuclear Equation of State in Intermediate Energy Heavy Ion Collisions

Elliptic flow ($v_2$) and hexadecupole flow ($v_4$) of light clusters have been studied in details for 25 MeV/nucleon $^{86}$Kr + $^{124}$Sn at large impact parameters by Quantum Molecular Dynamics model with different potential parameters. Four parameter sets which include soft or hard equation of state (EOS) with/without symmetry energy term are used. Both number-of-nucleon ($A$) scaling of the elliptic flow versus transverse momentum ($p_t$) and the scaling of $v_4/A^{2}$ versus $(p_t/A)^2$ have been demonstrated for the light clusters in all above calculation conditions. It was also found that the ratio of $v_4/{v_2}^2$ keeps a constant of 1/2 which is independent of $p_t$ for all the light fragments. By comparisons among different combinations of EOS and symmetry potential term, the results show that the above scaling behaviors are solid which do not depend the details of potential, while the strength of flows is sensitive to EOS and symmetry potential term.Comment: 5 pages, 5 figure

Bi- and tri-dentate imino-based iron and cobalt pre-catalysts for ethylene oligo-/polymerization

Recent progress on the use of iron and cobalt complex pre-catalysts for ethylene reactivity is reviewed. The review is organized in terms of the denticity of the chelate ligands employed, with particular reference to the influence of the ligand frameworks and their substituents on the catalytic performance for ethylene oligomerization/polymerization catalysis. The majority of the systems bear tri-dentate ligation at the iron/cobalt centre, though it is clear that bi-dentate iron/cobalt complex pre-catalysts have also attracted significant attention. Such systems produce in most cases highly linear products ranging from oligomeric α-olefins to high molecular weight polyethylene, and as such are promising candidates for both academic and industrial considerations

Incompressible SPH Based on Rankine Source Solution for Water Wave Impact Simulation

AbstractSmoothed Particle Hydrodynamics (SPH) is a Lagrangian meshless particle method. It was originally developed to simulate astrodynamics but has been extended to model dynamics problems with violent motions in many areas. This paper is based on ISPH and its pressure time history is transformed into another equation based on a Rankine source solution. In the new formulation of ISPH, the governing equation for pressure does not include any derivatives of unknown functions and so overcomes the problems associated with direct numerical approximation to second derivatives in existing ISPH formulation, and some important numerical handling techniques will also be included, like free surface particle identification method and solid boundary discrete scheme. The newly improved method will be applied to model various wave and wave impact interaction with different angle slopes, and the results of comparison with experimental data are also given. According to the comparison of pressure time history, this new method can get a good agreement with experimental results

Relativistic Correction to J/\psi Production at Hadron Colliders

Relativistic corrections to the color-singlet J/\psi hadroproduction at the Tevatron and LHC are calculated up to O(v^2) in nonrelativistic QCD (NRQCD). The short distance coefficients are obtained by matching full QCD with NRQCD results for the subprocess g+g\to J/\psi+g. The long distance matrix elements are extracted from observed J/\psi hadronic and leptonic decay widths up to O}(v^2). Using the CTEQ6 parton distribution functions, we calculate the LO production cross sections and relativistic corrections for the process p+\bar{p}(p)\to J/\psi+X at the Tevatron and LHC. We find that the enhancement of O(v^2) relativistic corrections to the cross sections over a wide range of large transverse momentum p_t is negligible, only at a level of about 1 %. This tiny effect is due to the smallness of the correction to short distance coefficients and the suppression from long distance matrix elements. These results indicate that relativistic corrections can not help to resolve the large discrepancy between leading order prediction and experimental data for J/\psi production at the Tevatron.Comment: 9 pages, 5 figure

Isospin dependence of projectile-like fragment production at intermediate energies

The cross sections of fragments produced in 140 $A$ MeV $^{40,48}$Ca + $^9$Be and $^{58,64}$Ni + $^9$Be reactions are calculated by the statistical abration-ablation(SAA) model and compared to the experimental results measured at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The fragment isotopic and isotonic cross section distributions of $^{40}$Ca and $^{48}$Ca, $^{58}$Ni and $^{64}$Ni, $^{40}$Ca and $^{58}$Ni, and $^{48}$Ca and $^{64}$Ni are compared and the isospin dependence of the projectile fragmentation is studied. It is found that the isospin dependence decreases and disappears in the central collisions. The shapes of the fragment isotopic and isotonic cross section distributions are found to be very similar for symmetric projectile nuclei. The shapes of the fragment isotopic and isotonic distributions of different asymmetric projectiles produced in peripheral reactions are found very similar. The similarity of the distributions are related to the similar proton and neutron density distributions inside the nucleus in framework of the SAA model.Comment: 7 pages, 4 figures; to be published in Phys Rev