Angular momentum dissipation in16O +58Ni collisions investigated by observation of light particles andγ rays
A systematic study of angular momentum dissipation in deep-inelastic heavy ion collisions is carried out by combining two experimental methods: the angular correlation ofα particles and protons in coincidence with deeply inelastic light fragments; and the first two moments of theγ-ray multiplicity. The unified analysis of these data, using a quantum mechanical treatment of the particle anisotropies and statistical decay calculations, yields most probable fragment spinsI0=10.8±1.1ħ and 13.4±1.1ħ for58Ni and62Zn, respectively, close to the sticking limit. For the width of the vector spin distribution assumed in our analysis to be equal in all three directions we obtainσ=3.9±1.3 ħ and 2.9±1.8ħ for58Ni and62Zn, respectively. These values correspond to most probable alignment parameters 〈Pzz〉=0.66±0.19 and 0.82±0.17 for58Ni and62Zn, respectively. As only very few partial waves of this light system undergo deep-inelastic scattering,σ directly relates to spin fluctuations, and is compared to asymptotic values from transport theories.