Gamma--gamma directional correlation studies on 77Ge decay

The decay properties of the levels in 77As were investigated following the decay of 11.3 hour 77Ge. Singles γ-ray energy and intensity measurements were obtained with a 54 cm3 high resolution Ge(Li) detector. Extensive γ-γ coincidence and directional correlation measurements were obtained with large coaxial Ge(Li) detectors. An improved decay scheme was constructed. From γ-γ correlation measurements, deduced log ft values, and internal conversion coefficients, the J/sup π/ values for the following levels were confirmed: g.s., 3/2-; 215.51, 3/2-; 264.41, 5/2-; 475.45, 9/2+; 614.49, 3/2- or 5/2+; 631.82, 5/2+; 1189.81, 7/2+; and 1560.67, 5/2+. Further J/sup π/ values were proposed as follows: 194.75, 1/2-; 1528.32, 5/2-; 1538.80, 3/2- or 5/2; 2000.16, 5/2+; 2341.64, 5/2 or 7/2; 2354.12, 5/2 or 7/2; and 2543.70, 5/2 or 7/2. The following delta(E2/M1) mixing ratios were obtained: 215.51-keV, -0.164 +- 0.16 or -0.321 +- 0.011; 558.02-keV, -0.139 +- 0.006; 810.35-keV, 0.194 +- 0.030 or 2.37 +- 0.18; 928.85-keV, -0.63 +- 0.41; 1263.86-keV, -1.41 +- 0.06 or -0.079 +- 0.013; 1312.80-keV, -5.86 +- 1.7 or -1.03 +- 0.11; and 1368-keV, -21. +- 12. or 0.519 +- 0.49