Measurements have been made of the γ-γ and the conversion-electron-γ directional correlations of the 121-280-keV and the 136-265-keV cascades in As75 following the decay of Se75. High-resolution Ge(Li) and Si(Li) detector systems were used exclusively, providing a significant degree of independence of these results from the effects of competing cascades. The Si(Li) electron spectrometer included a cooled field-effect transistor preamplifier to enhance its operation. The data are used to obtain the γ multipole mixing ratios δ and the internal-conversion particle parameters b2 for transitions in As75. A precise definition of the mixing ratios in terms of reduced emission matrix elements is given in order to determine their sign unequivocally so that a comparison with theoretical predictions will be unambiguous. The results are δ(280-keVγ)=-0.392±0.011, δ(265-keVγ)=-0.06±0.02, b2(E1;121-keVKe-)=-1.96±0.04, b2(E1;136-keVKe-)=-1.87±0.23. These values for the mixing ratios are discussed in light of those obtained in other experiments, and a comparison is presented of the results for the particle parameters with the theoretical predictions based on the point- and the finite-size-nucleus pictures. © 1969 The American Physical Society.
