The bremsstrahlung produced by electrons with incident energies of 0.5, 1.0, 20., and 2.8 MeV bombarding aluminum and iron targets of sufficient thickness to stop the electrons, has been measured. Spectral distributions of external bremsstrahlung intensity per unit solid angle, at representative emission angles ranging from 0 to 150 deg are presented graphically. Spectral distributions of radiation energy integrated over all angles and integrated over only the forward hemisphere are presented. Plots of total intensity as a function of angle show the degree of peaking in the forward direction with increasing electron energy. Total external radiation energy is found to vary as the square of the bombarding electron energy T0 over this energy range. The external efficiency for bremsstrahlung production is found to be 4.8×10−3 T0 for Al and 9.2×10−3 T0 for Fe, where T0 is in MeV.

A study has been made of the gamma radiation following the decay of Ir 192 . The energies, intensities, internal conversion coefficients and multipolarities of the gamma transitions have been determined. Energy level schemes for the daughter nuclei, Pt 192 and Os 192 , are proposed. The spins and parities of most of the levels are given.The spin of the first excited state of Mn 55 at 128 kev has been measured in the electric excitation process with 3-Mev alpha particles. Determinations of the K conversion coefficient and the angular distribution of the gamma rays lead to a spin assignment of 7/2" for the excited state and multipolarity Ml for the transition to the ground state. The K conversion coefficient (ax=0.0144db0.003) wa s measured by comparison with the known coefficient of the 137-kev transition in Ta 181 . The spin, parity, and transition probability are consistent with those expected for a rotational state.

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