Probing the limit of nuclear existence for heavy proton rich nuclei

A fundamental question in nuclear physics is, 'what are the limits on the number of protons and neutrons that can be bound inside an atomic nucleus?' The aim of this research proposal is to answer a vital part of this question by determining more carefully than ever before the precise location of what is known as the proton drip line. The proton and neutron drip lines are the borders between bound and unbound nuclei. Those at the proton drip line have such a large excess of protons that they are highly unstable and try to achieve greater stability through the process of proton emission. We propose to investigate, through complementary theoretical and experimental research programmes, how nuclear behaviour is affected when protons become unbound. Most of the established theoretical models of nuclei have been designed for and fitted to the properties of more stable nuclei. Thus by exploring the exotic nuclei at the farthest shores of the nuclear landscape, the deviation of their behaviour from those predicted by the standard models should be at its greatest and the inadequacies of those models revealed most dramatically. The proposal is for a new collaboration between the nuclear theory group at the University of Surrey and the experimental groups at Daresbury Laboratory and the University of Liverpool. The programme will extend both experimental knowledge and theoretical understanding of drip line nuclei. One of our standard tools for understanding nuclear behaviour is with a mathematical model called the 'mean field approach' in which individual protons and neutrons (collectively known as nucleons) are considered to move in an average energy field generated by all the other nucleons in that nucleus. Around the proton drip line it will be necessary to make use of mathematical techniques beyond this mean field picture to examine how nucleons interact with, and are 'aware of', each other's presence more accurately. Such behaviour, as for example the way two nucleons