Nuclear Physics consolidated grant

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The atomic nucleus was 'discovered' by Ernest Rutherford a hundred years ago. It comprises the tiny massive core at the centre of the atom. We now know that the nucleus is composed of protons and neutrons, and that these particles are themselves comprised of quarks, but this does not allow us to make a complete prediction of the behaviour of any given nucleus or isotope. The system is too complex, involving three of the four forces: the electromagnetic, weak and strong nuclear forces. The behaviour of the nucleus is often described as an emergent phenomenon as it cannot be readily predicted from its component parts. This drives theoretical effort and the need to benchmark theory with precision measurements. Our group addresses several fascinating aspects of the atomic nucleus: We study nuclei on the very limits of stability, in particular those with an excess of protons, and those which have the same number of protons and neutrons (N=Z nuclei). These nuclei exhibit special symmetries and deviations from these symmetries tell us very detailed information on the validity of competing nuclear models. Such measurements are very challenging as these nuclei are very difficult to produce in any quantity to perform experiments on. Our programme uses some of the principal facilities for nuclear physics worldwide where such exotic nuclei can be produced. A further aspect of our research into the structure of the nucleus concerns the shape of the nucleus. It is a remarkable property of the nucleus that it can adopt different shapes: spherical, oblate (smartie-shaped) and prolate (rugby-ball shaped) often for a small costs in energy. Predicting the shape of a nucleus and how this shape evolves as the nucleus is excited (given more energy) is extremely challenging from a theoretical perspective. Determining nuclear shape experimentally can help to discriminate between competing models of the nucleus and pin down our theoretical understanding. The third strand of our research is into the origin of the chemical elements in stars, and the role played by nuclear physics in this question. Some elements and isotopes are only produced in very hot and exotic events such as exploding stars: novae and supernovae. In these events, a rapid series of nuclear reactions takes place. We seek to understand how rapidly such reactions take place by reproducing them in the laboratory. This is very challenging as many of the nuclei involved in these studies are themselves radioactive and difficult to produce. Nevertheless, we are able to advance our understanding of how the chemical elements are created.