This report is the final in a series of preliminary reports that follow the studies of scavenging systems related to radioactive fallout. The project consisted of two phases: preliminary experiments to relate the sizes of particles in air to specific radioisotopes, and preliminary laboratory studies of scavenging of particles by liquid drops, including studies of sticking probability and effects of Brownian motion and water vapor diffusion.

Abstract: "The niobium-oxygen equilibrium has been determined by metallographic examination of arc-cast alloys made of electron-gun-refined niobium metal and special purity niobium pentoxide. Two intermediate oxides, NbO and NbO2, melt without decomposition at 1945 C and 1915 C, respectively. Eutectic reactions exist between niobium and NbO and 1915 C and between NbO and NbO2 at 1810 C. Experimental supports a peritectic reaction between NbO2 and Nb2O5 1510 C. The maximum solid solubility of oxygen in niobium metal is 0.72 weight per cent."

This is the final report on the progress, "A Wide-Range Neutron Detector and Monitoring Instrument," ARF 1118-6. This report covers activities from May 8, 1958 to May 8, 1959. This report describes the basic design principles of a proportional counter that has been constructed whose cathode diameter increases towards one end.