By use of small magnetic probes inserted into the discharge, the magnetic field distributions in the interior of a high-power pinched discharge have been measured as a function of time. From these data the current distributions can be deduced. By applying a static pressure calculation, in the cases when the radical pinch accelerations are small, the plasma pressure nkT in the pinch has been determined, with superimposed axial magnetic fields, and for stable and unstable configurations.

The total neutron cross sections for normal uranium, U235, and Pu239 are reported as a continuous function of energy for neutron energies between 40 and 7500 Kev. Three additional measurements were made between 17 and 20 Mev. The data were obtained from a good geometry transmission experiment in which 1-in.-diameter cylindrical samples were interposed midway between a neutron source and a neutron counter spaced at about 20 in. separation. In general, the statistical errors were within +- 0.2 barn. Measurements on normal uranium were in agreement with those made at Wisconsin in 1950 (LA-1060). The total cross section curves are almost identical for the three materials and very similar to those of other heavy elements. This suggests that the total neutron cross section for other heavy elements can be predicted with some accuracy.

"Report of the Survey of Los Alamos and Pueblo Canyon for radioactive contamination and radioassay tests run on sewer water samples and water and soil samples taken from Los Alamos and Pueblo Canyons." The objective of this report was to determine the extent and sources of radioactive contamination in the areas studied.

An accidental burst of radiation occurred at the laboratory on 1 February 1951 during remote control operation of a critical experiment. There was no personnel hazard. Normal operations were resumed within 24 hr, and the active material involved in the burst returned to service within three weeks. An unforeseen brief excursion into the prompt critical region was engendered in the act of scramming the assembly at the end of a series of measurements. This report describes the effects of the burst and analyzes the probable causes in some detail.

A polarographic method for the determination of titanium in the presence of plutonium has been devised. Hydrochloric acid solutions of plutonium and titanium are reduced with zinc, made one molar in tartaric acid, and further reduced in the polarographic cell with liquid zine amalgam. Plutonium is thus reduced to the non-interfering (III) oxidation state and a well defined anodic wave for the oxidation of titanium (III) to titanium (IV) is obtained. The height of this wave is directly proportional to the titanium concentration for plutonium-titanium solutions containing 20 grams plutonium per liter. The precision for the analyses of duplicate samples has been calculated at the 95 percent confidence level to be 2.9 percent for those containing 0.025 to 0.050 gm titanium per liter and 1.1 percent for those containing 0.089 to 0.51 gm titanium per liter.

The oxidation of uranium metal has been studied from the standpoint of the oxygen dependence of the reaction rate in an effort to establish the mechanism. The experimental data of Perkins agree with the theoretical dependence of the oxygen pressure derived this report. This agreement supports the hypothesis that the rate-controlling step in the migration of cations in the DO2 lattice, although the observed time dependence is not necessarily in agreement with this conclusion. Experimental entropies of activation are corrected for the observed pressure dependence. No firm conclusion could be reached as to whether the rate of diffusion or adsorption is rate-controlling.