Nuclear Astrophysics

The overarching driver of this theme is the understanding of the role of massive stars, their supernovae and resulting neutron stars, in the evolution of the Galaxy. We will expand on our well-established programme of explosive nucleosynthesis to encompass key stages in the massive star lifecycle where nuclear data are needed to interpret the wealth of observational data. We lead a programme of experiments at radioactive beam facilities (GANIL, TRIUMF, ANL) supported and complemented by stable beam experiments (TUNL, Orsay), to provide critical nuclear data for astrophysical models. We have a proven track record of astrophysical impact, from delivering innovative experimental approaches through to evaluation with state-of-the-art stellar and explosive models.

We will target, experimentally, key nuclear physics uncertainties that currently limit the interpretation of the wealth of astronomical observations now available across the life-cycle of massive stars. This ranges from their hydrostatic burning and nucleosynthesis, through to core-collapse supernovae, and the binary-system neutron star remnants of these. We will thereby determine the nuclear physics impact on astrophysical observables relevant to massive stars, right up to the point of neutron star mergers.
To address our research goals, we will expand our successful programme of direct measurements and transfer reactions, exploiting our recent technical developments in helium targets and building on existing expertise in silicon arrays and separators. Each research question requires a combination of methodologies to deliver the experimental information needed by the astrophysical models, and our track record demonstrates that we have the experience to perform such a range of experiments.

Following the life-cycle of massive stars, from hydrostatic burning, through CCSN to neutron star remnant, our specific goals are to:
1. Constrain the contribution of massive and very massive stars to galactic 26Al.
2. Push our 12C+12C cross section measurements into the Gamow window for the lightest massive stars.
3. Improve model predictions of weak r-process by providing cross section data on high priority (α,n) reactions.
4. Reduce the uncertainty on predicted 44Ti abundance in core collapse supernovae
5. Experimentally constrain the nuclear reactions powering X-ray burst light curves

These goals are all internationally recognised as critical to the advancement of our understanding of nuclear astrophysics and have been carefully chosen both for the necessity of nuclear physics data to interpret astronomical observations and for our expertise at York to deliver impactful measurements.

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