The nucleus lies at the heart of the atom, comprising a dense clump of protons and neutrons, collectively known as nucleons. As such, a stable element found on earth often consists of several isotopes, each with a different mass number of nucleons and, therefore, slightly different mass. The classical view of a nucleus is that of a homogeneous, spherical ‘bag’ of protons and neutrons. However, under some conditions the nucleons can clump together into groups or clusters. The extent to which nucleons inside the nucleus can clump together to form clusters in light systems, e.g. carbon, oxygen or neon, directly influences the astrophysical production, rate of decay and even the types of processes that can occur. Many stable light nuclei have equal numbers of protons and neutrons and naturally exist on earth. Such nuclei have been the focus of many studies into clustering. However, the scope of clustering away from stability – where the number of protons and neutrons is not the same – has yet to be fully investigated. This is the so-called exotic clustering regime which nuclei often live for only a few seconds before disintegrating. Studies of such systems will aid our understanding of, for example, some of the most energetic events in the universe – X-rays bursts – for which nuclear clustering is believed to enhance the onset reaction.
The aim of the project was to begin addressing the deficiency of data on exotic nuclei by implementing novel measurement apparatus for key short-lived isotopes using resonant elastic scattering – a method to map out nuclear energy levels by scattering and fusing two nuclei together before disintegrating into the initial components after a tiny fraction of a second – and at the same time demonstrate improvements to this spectroscopic tool that can be applied to a wide range of nuclear structure studies. By scanning out lots of energies during the fusion or scattering process, the internal structure of the compound or fused nucleus can be examined in detail. The new experimental apparatus was developed to perform such studies in addition to software for the subsequent data analysis. Both of these can be used by the nuclear physics community to perform similar experimental investigations that will help tie down the dominant astrophysical processes across a range of different stellar temperatures and elucidate the role that nuclear clustering plays. Put simply, the structure of the fused nucleus gives information about how probably it is to be formed at different temperatures in stars. Thus, how energy is released in different stars and other stellar objects can be inferred.
