Ghosh, T. K. | Search NASA

DOE OSTI2019

Constraining the symmetry energy with heavy-ion collisions and Bayesian analyses

Efficiency corrected single ratios of neutron and proton spectra in central Sn 112 + 112 Sn and Sn 124 + 124 Sn collisions at 120 MeV/u are combined with double ratios to provide constraints on the density and momentum dependencies of the isovector mean-field potential. Bayesian analyses of these data reveal that the isoscalar and isovector nucleon effective masses, m s ⁎ − m v ⁎ are strongly correlated. The linear correlation observed in m s ⁎ − m v ⁎ yields a nearly independent constraint on the effective mass splitting Δ m n p ⁎ = ( m n ⁎ − m p ⁎ ) / m N = − 0.05 − 0.09 + 0.09 δ . The correlated constraint on the standard symmetry energy, $S_0$ and the slope, L at saturation density yields the values of symmetry energy S ( ρ s ) = 16.8 − 1.2 + 1.2 MeV at a sensitive density of ρ s / ρ 0 = 0.43 − 0.05 + 0.05 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2017

Sorption of Ag and its vaporization from graphite at high temperatures

Not Available

Seelig, J. B. (ORCID:0000000214662537)↗

NASA NTRS1996

Cross-Effects in Microgravity Flows

Film growth by chemical/physical vapor deposition is a process of considerable interest in microgravity experiments. The absence of natural convection should allow better control of film growth processes but, in highly non-isothermal ampoules, thermal slip (creep) can become a matter of significant concern. The reported research is a theoretical and experimental investigation of the flow of gas/vapor mixtures under non-continuum conditions. The Boltzmann equation has been solved for a monatomic gas under non-condensing conditions and the various phenomenological coefficients have been computed. Computations for realistic potentials as well as for velocity and creep slip have been completed and the creep slip has been found to be dependent on the type of gas confirming the accuracy of previous variational results. The variational technique has been extended and planar flows calculated via the Burnett solutions. Velocity, diffusion and creep slips have been computed for gas mixtures and previously unknown dependencies of the creep slip on the mixture properties have been observed. Also for gas mixtures, an integral representation of the linearized Boltzmann operator has been developed for use in numerical and variational calculations for all intermolecular force laws. Two, two-bulb capillary systems have been designed, built and tested for the measurements of cross-flows; one of glass for isothermal measurements and one of stainless steel for non-isothermal measurements. Extensive data have been collected for Ar-He and N2-He mixtures at a variety of pressures and mole ratios. Viscosity, velocity slip coefficients and tangential momentum accommodation coefficients have been obtained from measurements with a spinning rotor gauge via a new theory that has been formulated for the spinning rotor gauge in the slip regime. The FIDAP fluid dynamics code has been applied to condensing flows in ampoules in the continuum regime and agreement obtained with the earlier work of Duval.

Loyalka, Sudarshan K.↗