Mesures de vies moyennes et de coefficients de mélange dans le noyau Mg

The mean lives of the lowest seven excited states of ²⁷Mg were measured in the ²⁶Mg(d, pγ) reaction with two different versions of the Doppler-shift attenuation method. Mean lives of τ_m = 1.4±0.3, 1.15±0.20, 0.89±0.16, 0.10±0.05, < 0.08, < 0.075 and 0.64±0.15 ps were found for the levels at E_x = 984, 1698, 1940, 3109, 3476, 3558 and 3762 keV, respectively. Gamma-ray angular distribution and γ-γ angular correlation measurements lead to the following mixing ratios: δ(1940 → 984 keV) = +0.05±0.04 and δ(984 → 0 keV) = −0.22±0.02. The deduced transition strengths are discussed in the framework of the Nilsson model.