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No abstract

A precise measurement of the cross section for the procluctio~l of C1I positron activity by the proton bombardment of natural carbon is described. Extensi1.e subsicliary esperiments were performed to evaluate the errors in the factors entering the measurerneIlt. The cross section is (03.3 f 0.3) X lo-" cnlL per atom of natural carbon for protons of range 0515 mg/cm? of alurninum (indicated energy 08.1 MeV). INTRODUCTIOS + inch thick. Twelve different targets were used. From the quoted chemical *Present address: hT~~clear-Chicago Corporation, Des I'laines, Illinois. ?The cross section \\rill be reported here as though C1l decayed entirely by positron emission. Scobie and Lewis (1057) have reported (0.19 f 0.03)y0 I< capture.

Cross sections of (p,pn), (p,p2n)

The isomeric state in Au196 decays to the ground state with an initial M4 transition of energy 175.5 ± 0.5 kev, followed by 148.2 ± 0.5 kev and 188.8 ± 0.5 kev transitions in cascade; a transition of 85.0 ± 0.5 kev is probably also in cascade with these transitions. There is evidence of a weak 135.9 ± 0.5 kev transition converted in Pt, indicating a small electron capture branch in the decay. The half-life of the isomeric state is 9.5 ± 0.3 hours.