Collinear Ternary Cluster Decay of Hyper-deformed $^{60}$Zn at High Angular Momentum

Binary and ternary cluster decay of $^{60}\mathrm{Zn}$ compound nuclei at high angular momentum, formed in the $^{36}\mathrm{Ar+{}^{24}Mg}$ reaction at $E_\mathrm{lab}$($^{36}\mathrm{Ar}$) = 195 MeV, has been measured in a unique kinematic coincidence set-up consisting of two large area position sensitive $(x,y)$ gas detector telescopes with Bragg-ionisation chambers(BRS). The BRS gives the opportunity to measure the reaction angles in- and out-of-plane, and through Bragg-curve spectroscopy to achieve a complete identification of the nuclear charge for different final channels. We observed very narrow out-of-plane angular correlations for two heavy fragments emitted in either purely binary events or in events with a missing mass consisting of 2 and 3$\alpha$-particles. These narrow correlations are interpreted as ternary fission decay from compound nuclei at high angular momenta through an elongated (hyper-deformed) shape with very large moment of inertia. In these stretched configurations the lighter mass in the neck region remains at rest or with very low momentum in the center of mass.