Based on the assumption that the noise contribution of a semiconductor detector is due solely to the bulk properties of the semiconductor, equations are presented which indicate the theoretical limits of noise in detector-amplifier combinations. These equations show that an optimum amplifier time constant and detector bias voltage exist for which condition the minimum noise is independent of the semiconductor resistivity. The optimum performance of a detector-amplifier system is shown to depend only upon detector area, input capacity (less detector capacity), semiconductor minority carrier lifetime, and the transconductance of the amplifier input tube. A new detector structure including a guard-ring electrode as an integral part of the detector structure is described which largely eliminates noise due to surface leakage. Experimental results for detector leakage and energy resolution are presented which agree well with theory.

Abstract: "The distribution ratios and equilibrium constants for the extraction of zirconium and hafnium from 4 M perchloric acid with various combinations of fluorinated [beta]-diketones and organic solvents have been determined. The separation factors K'Zr/K'HF, found for this acidity were: Z-thenoyltrifluoroacetone in benzene, 25; Z-thenoyltrifluoroacetone in o-dichlorobenzene, 16; benzoyltrifluoroacetone in benzene, 18; isovaleroyltrifluoroacetone in benzene, 13; isovaleroyltrifluoroacetone in n-hexane, 13."

The phase shifts for proton-proton scattering as calculated from the one-pion exchange contribution (OPEC) alone are of some interest because they describe the scattering correctly in the high angular momentum states, and because in the lower angular momentum states the deviation from the OPEC phases is an indication of the strength of the two-pion and higher exchanges processes. The attached table gives the proton-proton nuclear-bar phase shifts as calculated from OPEC. Phase shifts and mixing parameters are given in degrees, as function of the T, the laboratory kinetic energy of the incoming protons in Mev. Phase shift and mixing parameters are listed in the angular momentum states.

The following report describes the charged secondary particles from all presently known decay modes of positive K mesons that have been identified, and the masses of the primaries measured by the momentum-range method.