Nuclear Physics Rolling Grant

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The majority of the mass of the universe is made up of atomic nuclei that lie at the centre of the atom. The fundamental questions in nuclear physics are, 'What are the limits of nuclear existence?'; 'What are the heaviest nuclei that can be made in the laboratory?'; 'What are the limits on the angular momentum that a nucleus can sustain before fission?'; 'Do new forms of collective motion occur far from the valley of nuclear stability?' How does the ordering of quantum states, alter in highly dilute or neutron-rich matter?' The aim of this research proposal is to try to answer these questions. No one yet knows how heavy a nucleus can be; in other words, just how many neutrons and protons can be made to bind together. We will study the heaviest nuclei that can be made in the laboratory and determine their properties which will allow better predictions to be made for the 'superheavies'. For lighter nuclei we will explore in the region of the proton and neutron drip lines, which are the borders between bound and unbound nuclei. We will determine more carefully than ever before the precise location of these drip lines. As we approach the neutron drip line, only accessible for light nuclei, we will explore how the fundamental nuclear forces change their behaviour in diffuse neutron matter. On the other side of the line of stability, those at the proton drip line have so much electrical charge that they are highly unstable and try to achieve greater stability through the process of proton emission. We will investigate how nuclear behaviour is affected when protons become unbound. For these exotic systems we will also explore how the nucleus prefers to rearrange its shape, which can be a sphere, rugby ball, pear, etc. and how it stores its energy among the possible degrees of freedom. We will also investigate how the properties of these nuclei develop as we make them spin faster and faster. We will try to determine more carefully than ever before the precise nature of ultra high spin states in heavy nuclei, just before the nucleus breaks up due to fission. This programme of research will employ a large variety of experimental methods to probe many aspects of nuclear structure, mostly using instrumentation that we have constructed at several world-leading accelerator laboratories. The work will require a series of related experiments at a range of facilities in order for us to gain an insight into the answers to the questions posed above. These experiments will help theorists to refine and test their calculations that have attempted to predict the properties of nuclei, often with widely differing results. The resolution of this problem will help us to describe the complex many-body system that the nucleus represents.