M1−E2Mixing Ratios and Conversion-Electron Particle Parameters for the Electromagnetic Transitions inAs75

Abstract

Measurements have been made of the 7-7 and the conversion-electron-7 directional correlations of the 121-280-keV and the 136-265-keV cascades in As 75 following the decay of Se 76 . 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 fieldeffect transistor preamplifier to enhance its operation. The data are used to obtain the 7 multipole mixing ratios 8 and the internal-conversion particle parameters hi for transitions in As 75 . 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 8 (280-keV 7) = -0.392±0.011,S(265-keV 7) --O.06±0.02, fc(JEl; 121-keV K e")= -1.96±0.04, b 2 (El; 136-keV K e~) --1.87=1=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.

Mixing ratios in67Zn determined by gamma-gamma angular correlations

“…The sign convention for 6 follows the suggestion of Becker and Steffen [4]. The results are summarized in Table 2.…”

Gamma-gamma angular correlation studies in97Tc

“…The mixing-ratio 6 given in the text and the tables has a sign according to the suggestion of Becker and Steffen [16]. The 12-channel MCG was used in the study of this cascade.…”

Gamma-gamma directional correlations in the decay of206Po

“…E2/M 1 mixing ratios determined by the method of least squares using the directional correlations coefficients A z and L1/L2-subshell ratios. The sign convention for 6 follows the suggestion of Becker and Steffen [9] E (keY) The present limits are given by the overlapping area in respectively figure. Also results from L-subshell ratios [6] Table 2 (522) …”

“…The mixing ratios compatible with both correlation and conversion electron data (found from the overlapping area in respectively figure) are then presented in Table 3. The sign of the mixing ratios is throughout defined in accordance with the use of emission matrix elements [9].…”