Multi-detector registration system for the study of multi-body decay of heavy body nuclei

Malaza, Vusi David (2012-12)

Thesis (MMil)--Stellenbosch University, 2012.

Includes bibliography

Thesis

Nuclear ssion is commonly known as a process where a heavy nucleus such as Uranium or Thorium decays into two fragments of roughly equal mass. On occasion however, instead of decay into two parts a process known as binary ssion, the nucleus can decay into three fragments. In this decay channel known as ternary ssion, the nucleus splits into three fragments with the third particle being too light compared to the main ssion fragments. There are also instances where heavy nuclei split into three fragments of comparable masses, the so called \true ternary ssion" as was predicted by the theoretical calculations of Strutinsky [Str63]. While theoretical predictions hold promises for this decay mode, experimental attempts had little success in proving the existence of true ternary ssion in low energy ssion. The challenges and di culties faced by experimentalist in con rming the existence of true ternary ssion also proved that this ssion mode is a very rare phenomenon. This thesis is devoted to the investigation of ternary ssion know as collinear cluster tripartition (CCT) in spontaneous ssion of 252Cf, and the design and development of two time-of- ight spectrometers aimed at identifying all collinear multi-body decay partners directly. Prior to this study the only technique that was used at identifying decay partners in CCT was the \missing mass" approach. In this approach only two partners are identi ed directly with the third partner being identi ed by subtracting the two observed partners from the initial mass of the nucleus. The experimental results from the two spectrometer setups showed that it was possible to identify all three partners of the CCT channel. The results also con rmed the existence of the so called \Sn lost" CCT mode which was already observed in earlier experiments.

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