FAUST

Since the dawn of mankind, the human race has been fascinated with the stars. However, 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?" Or, put in a different way, "where do all the chemical elements come from?"

From as early as the 1920s, it was suggested that nuclear reactions generate the energy that makes stars shine, but it wasn't until a number of years later that these same nuclear reactions were discovered to be responsible for the creation of almost all of the chemical elements. Specifically, 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, which enriches the Universe with the products of nucleosynthesis, provides the building blocks for the birth of new stars, planets and even life itself. In fact, our own Sun and its complement of planets were created from such material gathered from the debris of stellar ancestors. Consequently, every living creature on Earth can be viewed as being made of stardust.

More recently, astounding advancements in astronomy have produced unprecedented observational data on explosive astrophysical phenomena in our Universe. Such observations have allowed us to infer much about the production of chemical elements throughout the cosmos. However, rather astonishingly, many key stages of stellar nucleosynthesis are still not fully understood, owing to large uncertainties in the underlying properties of microscopic, unstable nuclei.

Meaning that, although we know the stars are responsible for the formation of chemical elements, it is still not known, in many cases, which types of stars produce which elements.

In this regard, atomic nuclei have been probed more or less exclusively by studying collisions between stable beams and stable targets over the past hundred years. This has restricted the nuclei that could be studied to just a small fraction of those that are thought to exist. In particular, most of the nuclei important for driving the creation of elements in stars have, up until now, been inaccessible to experiment.

However, with the advent of the next generation of radioactive beams facility, FRIB, in the USA, which came online earlier this year (2023), it is now possible to produce accelerated beams of unstable nuclei that only exist for fractions of seconds to minutes, to perform nuclear reaction experiments. By developing a unique charged-particle detection system, called FAUST, which is specifically designed to probe the properties of unstable nuclei, we will be able to unravel key mysteries surrounding the formation of chemical elements in the Universe and obtain critical information for understanding the fundamental strong force.

The FAUST project brings together two of the largest nuclear physics groups in the UK (The University of Surrey and the University of York), who specialise in the use of silicon strip detector technology and direct nuclear reaction studies, and the STFC Daresbury Laboratory. The goal of the FAUST project is to develop an advanced silicon strip detector array to detect charged particles, over a wide range of angles, following nuclear reactions with unstable beams delivered by the FRIB accelerator system.

Such charged particles are emitted with very high energies and cannot be studied with conventional systems. Furthermore, FAUST will be used in conjunction with the world's leading gamma-ray array, GRETA, to establish a global flagship detection system for the study of unstable nuclei.