Time differential angular correlation measurements on 160Dy and the electric quadrupole moment of the first excited state

Abstract

The statistical perturbation of the angular correlations of the 1178 keV-87 keV cascade and the 879 keV-87 keV cascade of 160Dy has been investigated by time differential measurements. We used liquid sources of 3 + ions of 160Tb in 1 N perchloric acid, 1 N sulphuric acid, and 0.01, 1.0, 3.0 and 10.0 N hydrochloric acid. In all cases the measured angular correlation coefficients A 2 and A 4 are well described by single exponential functions. The results for the attenuation parameters λ 2 and λ 4 for the perchloric solution and the solution in sulphuric acid are: λ 2 = (0.0686 ± 0.0054) · 10 9 sec −1 λ 4 = (0.2118 ± 0.0186) · 10 9 sec −1 sulphuric acid, λ 2 = (0.0687 ± 0.0074) · 10 9 sec −1 λ 4 = (0.2102 ± 0.0193) · 10 9 sec −1 perchloric acid, respectively. The values of hydrochloric acid observed for different normalities agree within the limits of error. The weighted average is: λ 2 = (0.0804 ± 0.0030) · 10 9 sec −1 λ 4 = (0.2452 ± 0.0082) · 10 9 sec −1. We observed no indication of an influence of the chemical structure on the ratio of λ 4/ λ 2. The average of all measurements is λ 4/ λ 2 = 2.10 ± 0.15 (4.9 %). From this ratio we derive for the electric quadrupole-moment of the first excited state the value (1 − R) Q sp, = 1.67 ± 0.46 b. This result is in agreement with Coulomb excitation data.