Reaction independent analysis of gamma ray angular distributions from Ge(Li)-detector measurements

Abstract

Reaction-independent analysis of particle-γ angular correlations from aligned nuclei involves particle detection near 0° or 180°, and is generally limited by the energy resolution of the particle counter if a NaI(Tl) counter is used to detect the γ-rays, and by the relatively low coincidence rates if a Ge(Li) counter is used. Under certain circumstances, an alternative method, which does not require particle-γ coincidences, is the simultaneous analysis of the angular distributions for two or more γ transitions from the same nuclear state. High resolution angular correlation information can thus be obtained using a Ge(Li) detector. Angular distribution data for several spin-2 levels in 42Ca and 58Ni serve as illustrations of this method. It is shown that E2/M1 mixing ratios for 2 → 2 transitions can be evaluated with an accuracy comparable to particle-γ or γ− γ angular correlation measurements.