Measurements of the quadrupole moments of the first 2+ states of 150Sm and 194Pt by the reorientation precession technique

We have observed the influence of the nuclear quadrupole moment on the γ-ray angular correlation following Coulomb excitation by heavy ions scattered through angles of about 90°. A prolate quadrupole moment precesses the γ-particle correlation in the opposite direction to that produced by a moment of oblate shape. The method has been applied to the first 2⁺ states of ¹⁵⁰Sm and ¹⁹⁴Pt, which are found to be prolate, Q=-1.25±0.2 b, and oblate, Q=+0.77±0.5 b, respectively.