Nuclear excitation by electron capture (NEEC)

The origin of the heavy elements is one of the key questions in science. It has come into particular focus in recent years where the combination of gravitational wave astronomy and more conventional astronomical imaging has shown that merging neutron stars are the most likely site of the astrophysical r-process in which heavy elements like gold are produced through rapid neutron capture reactions. There are many outstanding questions about the r-process. One question centres around the role of isomers, long-lived excited states of nuclei. Isomers are likely to sit at various points of the pathway for r-process nucleosynthesis. If there are mechanisms which could depopulate these isomers then the overall nucleosynthesis process could change and hence the final abundances of heavy elements. One mechanism identified as potentially playing a role in the high temperature/density conditions where the r-process occurs is nuclear excitation by electron capture (NEEC). This is where a transition between two excited states in a nucleus occurs where the energy required to drive the transition comes from capturing an electron into a bound atomic orbital.

The aim of this PhD project will be to achieve experimental confirmation of the NEEC process. This is both topical and high profile research following a claim to have made the first observation of NEEC in the laboratory reported in Nature in 2018. This work has raised many questions as the probability for NEEC which was claimed exceeds the best theoretical estimates by many orders of magnitude.

The quest to observe NEEC will draw on many different branches of physics as a nuclear transition driven by electron capture naturally connects nuclear physics and atomic physics while observing such a process would have important implications for astrophysics. Moreover, options for observing NEEC in the laboratory include experiments at nuclear physics facilities with accelerated beams as well as experiments in hot plasmas created by some of the world’s most powerful petawatt lasers.

The PhD project will entail identifying candidate isomers to study and matching these to the most appropriate facilities and experimental approaches. The project will involve experiments at one or more international accelerator or laser facilities. Here, the student will participate in setting up and running the experiment and analysing the data. There will also be opportunity to present the work at relevant international conferences.

This project would suit a student with a broad interest in physics and astrophysics. This funded studentship is open to home students only and is supported by AWE.

How to Apply:

Applicants must apply via the University’s online application system at https://www.york.ac.uk/study/postgraduate-research/apply/. Please read the application guidance first so that you understand the various steps in the application process. To apply, please select the PhD in Physics for September 2024 entry. Please specify in your PhD application that you would like to be considered for this studentship.

Privacy notice:

In addition to the data sharing outlined in the University’s Privacy Notice – student applicants, applications will be shared with the industrial partner for the shortlisting process and interview panels. The industrial partner will delete details of unsuccessful applications once the selection process is complete.