Nuclear Physics in the Cosmos

点击翻译按钮获取中文摘要

Since the dawn of mankind the human race has had a fascination with the stars but it's only in the last century that we have truly begun to understand their significance in answering our deepest of questions, "where do we come from?" In the early 1920s, it was suggested that nuclear reactions generate the energy that makes stars shine. These same nuclear reactions were then later discovered to be responsible for the creation of almost all of the chemical elements. When stars come to the end of their life cycles, their fuel finally spent, they can eject part or all of their matter into the Universe via stellar outbursts and cataclysmic explosions. This material provides the building blocks for the birth of new stars, of planets and of life itself. Our own Sun and its complement of planets were created from such material gathered from the debris of stellar ancestors. Thus, every living creature on Earth can be viewed as literally being made of stardust.Recent advances in astronomy and in the analysis of meteoritic inclusions have provided unprecedented observational data on astrophysical phenomena that enrich the Universe with their ejecta or outflow. In particular, pre-solar grains, tiny pieces of material found in meteorites, are revealing a wealth of information on the abundance of chemical elements produced in cataclysmic events, such as Supernovae, that occurred prior to the formation of the Solar System. In contrast, modern space-based telescopes provide a fresh insight into the properties of ongoing stellar processes occurring in our Galaxy. These two massive leaps in observational astronomy have broadened our knowledge of stellar environments tremendously. However, quite astonishingly, many key stages of stellar nucleosynthesis are still not fully understood, owing to uncertainties in the underlying nuclear reaction processes that drive the stellar outbursts. My research focuses on resolving these issues, by investigating the nuclear reactions involved in astrophysical environments, with the ultimate goal of allowing a meaningful comparison to be made between theoretical models and astronomical observations. It should be noted that the study of nuclear reactions that occur in stellar interiors is notoriously difficult for the experimenter. This is due to the formidable task of recreating the extreme conditions of stellar phenomena in a terrestrial laboratory. However, by using innovative experimental techniques, it is possible to bypass this problem and investigate the nuclear reactions of interest indirectly. These indirect investigations represent the bulk of my research programme. In each study, key nuclear physics information is obtained on the unstable end products of an astrophysical process and used to determine the rate at which the nuclear reaction takes place. These rates govern both the energy generation and path of nucleosynthesis in stellar environments and as such, have a strong influence on the observational properties of the astrophysical phenomena under investigation. This is an extremely exciting area of physics research, providing an interlinking between the fields of nuclear structure and reactions and astronomy and astrophysics.