Lifetimes of the TSD candidate bands in 157,158Er at ultra high spin

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The nuclei 157,158Er have both single particle and collective structures at very high spin. This conclusion has been based on the measurement of gamma ray energies and energy levels. Rotational bands have been found at very high spin in both nuclei. Based on the gamma ray energies measured this band has the characteristics of a deformed band. The moment of inertia that can be deduced from the gamma ray energies is lower than expected from a superdeformed band and its behaviour as a function of spin is like that in triaxial bands found in heavier nuclei. In this experiment lifetimes will be measured which can then be used to determine transition strengths. These are a more exact measure of both deformation and triaxiality than the gamma ray energies alone. The experiment will be carried out using the GAMMASPHERE array at Argonne National Laboratory in the USA. Data will be collected for 12 days. The data will then be analysed in Liverpool in order to achieve the physics aims. The data will form part of the thesis of a resarch student.