The viscosity of a liquid plutonium-iron eutectic alloy, which contains 9.5 atom per cent iron and melts at 411 degrees C, was determined up to 808 degrees C at Mound Laboratory by an oscillating cup viscosimeter. This type of apparatus employed a right-circular cylindrical cup containing the liquid under investigation attached to a torsion fiber. The dampening effect of the liquid upon the normal oscillations of the pendululm was a function of the viscosity of the liquid. The amplitudes of the oscillations of the pendulum were measured by a photographic technique. The periods of the oscillations were determined by an automatic timing mechanism. The reliability of the viscosimeter was demonstrated by following the expected function of the viscosity of liquid lead and bismuth over a larger temperature range than was previously reported.

The constitution of the plutonium-copper binary alloy as determined by differential thermal analysis is presented. The system is characterized by two congruent melting compounds, PuCu2 (m.p. 865 degrees C.) and Pu4Cu17 (m.p. 954 degrees C.); two incongruent melting compounds, PuCu4 (m.p. 906 degrees C.) and Pu2Cu11 (m.p. 926 degrees C.); three eutectics, 96 atom per cent copper (m.p. 626 degrees), 70.5 atom per cent copper (m.p. 849 degrees C.), and 91 atom per cent copper (m.p. 881 degrees C.); and two peritectics at 75 atom per cent (m.p. 906 degrees C.) and 85.5 atom per cent (m.p. 926 degrees C.). Solid solution was found above 97 atom per cent plutonium. The apparatus, the method of investigation, and the binary alloy phase diagram is discussed.

A Po/sup 210/ source was used to furnish a reliab1e ground for both electron and positron sources. This was done to prevent the electron and positron sources from charging during BETA spectral studies in magnetic lens spectrometers. An approximately 20- mu c Po/sup 210/ source was placed 1.2 in. behind a 4- mu c Na/sup 2 / 2>s positron emitter backed by 20- mu g/cm/sup 2/ Formvar in the spectrometer; this arrangement resulted in a charging rate decrease of approximately 80%. When the source was placed 0.5 in. away, no charging was detectable over a period of more than one week. The discharge is attributed mainly to the loss of electrons from the source and backing caused by ionization of alpha particles since few alpha particles are stopped near the source. (B.O.G.)

The results presented here have shown that the spectral signature of absorption in a cloudy layer could be duplicated (except for the 1.06 {micro}m region) with a rather sophisticated radiative transfer model, if the absorption by both aerosol and cloud droplets was enhanced. In the case of aerosol, highly absorbing (imaginary part of refractive index between 0.1 and 0.01), small (2 - 5 nm) particles dramatically improved the match between observations and model computations. Duplication of the observed cloud absorption required a thin layer of drizzle (large droplets). The only feature remaining unexplained at this time is the enhanced absorption at 1.06 {micro}m. These results are only based on one day of observations and need to be verified. This study suggests the need for additional co-located broadband and spectral observations in clear and cloudy sky conditions in different atmospheric regimes. In-situ aerosol and cloud droplet microphysical measurements will be crucial to unravel the role of these particles in the ''enhanced absorption'' issue. Finally, accurate absorption measurements are needed at 1.06 {micro}m to understand observed absorption in that spectral region.