The fission and spallation reactions caused in uranium by bombardment with high energy protons (340 t o 350 MeV) were investigated. The reaction products were separated from the target by chemical processes and identified by their radioactive properties. The relative yields of the observed fission products were measured, and the results plotted as a function of mass number. Several of the spallation products were identified and their yields estimated. An attempt was made to determine the most probable atomic number for a nuclide of given mass formed directly from fission. Studies were made of the relative yields along several isobaric chains as a function of atomic number. From these data predictions of the mass and charge of the fissioning nucleus are made.

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The slow neutron transmission of several samples of plutonium is being investigated with the Columbia Neutron Velocity Spectrometer. The spectrometer, which has been described previously (Rainwater et al., Phys. Rev. 71, 65 (1947)), was recently improved, recalibrated, and the operational factor reevaluated (CUD-59). Results reported here were obtained by the procedure described in that report.