Coplanar ternary cluster decay of hyper-deformed $^{56}$Ni and $^{60}$Zn at high angular momentum
Résumé
Using a unique two-arm detector system for heavy ions (BRS, binary reaction spectrometer) coincident fission events have been measured from the decay of 60Zn and 56Ni compound nuclei formed at 83–88 MeV excitation energy. From the binary coincidences inclusive and exclusive cross sections for fission channels with differing losses of charge were obtained. Narrow out-of-plane correlations corresponding to coplanar decay are observed for two fragments emitted in binary events, and in the data for ternary decay with missing charges from 4 up to 8. Differential cross sections for the different binary and ternary fission channels are obtained. The ternary cluster fission can be explained by the statistical decay from equilibrated compound nuclei with hyper-deformed shapes with angular momenta around 45–52 h.