We present a new, publicly available set of Los Alamos OPLIB opacity tables for the elements hydrogen through zinc. Our tables are computed using the Los Alamos ATOMIC opacity and plasma modeling code, and make use of atomic structure calculations that use fine-structure detail for all the elements considered. Our equation of state model, known as ChemEOS, is based on the minimization of free energy in a chemical picture and appears to be a reasonable and robust approach to determining atomic state populations over a wide range of temperatures and densities. In this paper we discuss in detail the calculations that we have performed for the 30 elements considered, and present some comparisons of our monochromatic opacities with measurements and other opacity codes. We also use our new opacity tables in solar modeling calculations and compare and contrast such modeling with previous work.

A comprehensive set of calculations of the radiative losses of solar coronal plasmas is presented. The Los Alamos suite of atomic structure and collision codes is used to generate collisional data for 15 coronal elements. These data are used in the Los Alamos plasma kinetics code ATOMIC to compute the radiative power loss as a function of electron temperature. We investigate the sensitivity of the loss curves to the quality of the atomic data and changes in the coronal elemental abundances, and we compare our results with previous work.

Depending upon the properties of their compact remnants and the physics included in the models, simulations of neutron star mergers can produce a broad range of ejecta properties. The characteristics of this ejecta, in turn, define the kilonova emission. To explore the effect of ejecta properties, we present a grid of two-component 2D axisymmetric kilonova simulations that vary mass, velocity, morphology, and composition. The masses and velocities of each component vary, respectively, from 0.001 to 0.1 M ⊙ and 0.05 to 0.3 c, covering much of the range of results from the neutron star merger literature. The set of 900 models is constrained to have a toroidal low electron fraction (Y e ) ejecta with a robust r-process composition and either a spherical or lobed high-Y e ejecta with two possible compositions. We simulate these models with the Monte Carlo radiative transfer code SuperNu using a full suite of lanthanide and fourth-row element opacities. We examine the trends of these models with parameter variation, show how they can be used with statistical tools, and compare the model light curves and spectra to those of AT2017gfo, the electromagnetic counterpart of GW170817.

The K shell excitation of H-like uranium (U(91+)) in relativistic collisions with different gaseous targets has been studied at the experimental storage ring at GSI Darmstadt. By performing measurements with different targets as well as with different collision energies, we were able to observe for the first time the effect of electron-impact excitation (EIE) process in the heaviest hydrogenlike ion. The large fine-structure splitting in H-like uranium allowed us to unambiguously resolve excitation into different L shell levels. State-of-the-art calculations performed within the relativistic framework which include excitation mechanisms due to both protons (nucleus) and electrons are in good agreement with the experimental findings. Moreover, our experimental data clearly demonstrate the importance of including the generalized Breit interaction in the treatment of the EIE process.

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The electron-impact excitation of the individual levels that constitute the 4p 5 5s configuration of Kr is experimentally and theoretically investigated at incident electron energies of 20.0, 15.0, 13.5 and 12.0 eV, for scattering angles ranging from 10 • to 135 • . High resolution electron energy-loss spectroscopy is used to obtain spectral intensities for the excitation of each of the four 4p 5 5s levels from the ground state. The intensities lead to three differential cross section ratios. Absolute electron-impact excitation cross sections are then determined by normalization to elastic scattering cross sections using the conventional inelastic to elastic normalization method. The present theoretical cross sections are calculated using two different methods, namely the R-matrix method and the unitarized first-order many-body theory. Comparisons between the experimental and the theoretical results show some good agreement, but reveal areas where significant improvement of the present models is needed. Additionally, it is shown that in the present case, just as in general for the rare gases, differential cross section ratios provide a sensitive test of theoretical models as well as unique insights concerning relativistic effects in the scattering process. Comparisons with existing models and other experimental data are also presented.

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We present new experimental measurements and theoretical calculations of R-matrix and unitarized first-order many-body theory for electron-impact excitation of krypton. The usefulness of differential cross section ratios in providing sensitive tests of electron scattering models for the excitation of the configuration of the heavy rare gases is demonstrated. In addition to differential cross sections alone, these ratios provide interesting physical insights into the details of the collision process. Comparisons of the measured ratios with predictions from the present and other available calculations show some agreement, but also reveal that significant improvements of these models are required.