Kernspektroskopische untersuchungen AN 8Li, 42K, 86Rb, 141Ce, 144Ce, 144Pr und 203Hg

Zusammenfassung The half-lifeof 8 Li has been found to be T 1 2 = 0.854±0.008 sec. The 2 − → 2 + β-groups of 42 K and 86 Rb were measured with the Heidelberg intermediate-image spectrometer. The shape factors show large deviations from the statistical shape with large statistical errors, however, in the case of 86 Rb. The integral β-circularly polarized γ-correlations were measured by Compton forward scattering. For 42 K, rather uncertain best values for the six matrix elements were obtained. The β-circularly polarized γ-correlation of 141 Ce is characterized by an asymmetry parameter ω = −0.16 ± 0.05 , which favours a value of X in the range 4.5 X X is the matrix element ratio in the ξ-approximation. In the cases of 144 Ce and 203 Hg, the reduced anisotropy coefficient ϵ′ of the β-γ directional correlation was found to be positive and not strongly energy dependent ( 144 Ce), and negative and strongly energy dependent ( 203 Hg). The β-circularly polarized γ-correlations of 144 Ce, 144 Pr and 203 Hg were measured. The 144 Ce correlation has ω = 0.64 ± 0.25 . The 144 Pr results (two cascades) agree with the formerly established value of 0 − for the 144 Pr ground state. The 203 Hg result ω = −0.18 ± 0.04 confirms the negative sign of the β-transversely polarized conversion electron correlation. The results are discussed with respect to the ξ-approximation.