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The Chandrasekhar H‐equations for matrix‐valued functions are solved by an iterative method. Complex variables and positivity techniques are used to obtain convergence. This approach may be applied to subcritical neutron transport in a slab with isotropic scattering.

Using the results of an acoustic reverberation experiment at 75 kHz, in which the active volume was localized to the vicinity of the source and receiver, the volume scattering coefficient is calculated and compared to the attenuation coefficient. Assuming isotropic scattering, the conclusion is reached that scattering does not significantly affect the pressure dependence of acoustic attenuation in the ocean at this frequency.

The effects of chemical binding and thermal motion on the extrapolation distance in the thermul-neutron Milne problem with isotropic scattering from a nonabsorbing medium are discussed. (R.E.U.)

A six-flux theory is derived for the diffuse reflectance and fluorescence of mixed powder samples of various shades of gray. One component of the powder is assumed to be fluorescent, with nonoverlapping excitation and emission bands. For symmetrical normal illumination and isotropic scattering, the six-flux reflectance reduces exactly to the Kubelka-Munk (two-flux) expression. Measurements of the fluorescence of a series of silica-silicon carbide-calcium tungstate mixed powder samples, which were found to vary over a range of 60:1, correlate well with the six-flux theory over the full range, whereas a two-flux theory is satisfactory only at high sample reflectances.

Hunter (1977) found that a Monte-Carlo simulation of electron swarms in hydrogen, based on an isotropic scattering model, produced discrepancies between the predicted and measured electron transport parameters. The present paper shows that, with an anisotropic scattering model, good agreement is obtained between the predicted and experimental data. The simulation code is used here to calculate various parameters which are not directly measurable.

A description is given of the results of the application of singular integral equation theory to Chandrasekhar's X- and Y-functions. Both exact and asymptotic formulae are given for the unique functions which are analytic functions of their argument. Computations are reduced to the solution of rapidly convergent Fredholm equations and to the calculation of various quadratures. Numerical tables for the case of isotropic scattering will be published as a supplement to the Astrophysical Journal. (Author)

The Rayleigh ratio of the light scattered at 90° by solutions of three simple electrolytes has been measured with high precision using a modified Brice Phoenix light-scattering photometer. From the results obtained at wavelengths 546 and 436 mµ the contribution Rc.f. to the scattering due to fluctuations in concentration of the solute has been calculated from the total isotropic scattering of the solutions and the contribution Rd.f. from the density fluctuations on the system. The quantities Kc/Rc.f. so obtained are compared with (–∂ ln a0/∂c)p,T obtained from activity data. Also included are measurements on the refractive index, refractive index increment and depolarization of the solutions at wavelengths 546 and 436 mµ.

Time dependent radiative transfer equation for plane-parallel isotropic scattering medium in first Gaussian approximation

In this paper X- and V-functions which occur in the solution of transfer problems in atmospheres of finite optical thicknesses and scattering radiation isotropically with an albedo ϖ 0 ≤ 1 for single scattering are tabulated. The values of the albedo, ϖ 0 , and optical thickness, τ, for which solutions are tabulated are: ϖ 0 = 1, 0,95,0,9,0,8,0,5, and τ = 0,05,0,10,0.15,0,20,0,25,0,5, and 1.

Approximate forms are developed for the X- and Y-functions of isotropic scattering of Chandrasekhar in terms of the well-tabulated H -function. The approximl]. tions that are asymptotically correct for slabs of large thickness are compared with available tabulated values.

In a recent paper, Crompton, Elford, and Robertson (1970; hereafter referred to as CER) considered certain questions concerning the steady-state distribution of electrons moving in a neutral gas under the influence of a uniform electric field E. The present communication comments on some aspects of the error discussion in the Appendix of the paper by CER. The analysis will be restricted to the case of isotropic scattering.