Unlocking the mysteries of the neutrino and its mass through the nucleus

Neutrinos are everywhere! The most abundant massive particles in the universe, they come from all sorts of places: the Sun, the Earth, and outer space. Trillions of them pass harmlessly through our bodies every second. However, they are extremely hard to detect, meaning that neutrinos remain some of the most mysterious particles in the universe - and the only ones whose behaviour can't be fully explained by the Standard Model, the complicated equation describing all the fundamental particles in the universe.

Because they are electrically neutral, neutrinos are invisible to particle detectors, which are sensitive to electric charge. We can only detect them when they interact with matter, and produce their charged partners - particles like electrons - with one of three "flavours". Neutrinos are predicted to have zero mass - like photons, the particles of light - but we now know that they have (tiny) masses and that they "oscillate", changing flavour in flight. This raises questions - what are their masses and how do they correspond to the flavours, how do they acquire mass, and do neutrinos and their antiparticles behave differently?

Experiments investigating these questions use many different approaches, typically involving huge particle detectors, built deep underground. However, they all face a common challenge: interpreting their measurements requires understanding how neutrinos interact with atomic nuclei. This is extremely complicated, depending on subtleties of nuclear structure and myriad interaction mechanisms that mimic each other in detectors. Nevertheless, without better interaction models, next-generation neutrino experiments will not be able to achieve the precision they need to make new physics discoveries.

This fellowship proposes a novel, integrated approach, studying how nuclear effects manifest in different experiment types. We'll use data from SuperNEMO, located under the French Alps and seeking the rare neutrinoless double-beta decay, a never-observed process that could help explain our matter-dominated universe. We'll add precision electron-scattering measurements from CLAS, at Jefferson Lab in Virginia; and use neutrino-scattering data from SBND, a liquid-argon-based detector at Fermilab in Illinois, to test and improve nuclear models. We'll implement them for DUNE, a next-generation oscillation experiment with huge investment from the UK and beyond, which will study a beam of neutrinos travelling from Fermilab to the SURF lab, in a former gold mine in South Dakota.

With a unique background studying both neutrino interactions and neutrinoless double-beta decay, this fellowship will give me the chance to bring all of these ideas, data and opportunities together, and bring us closer to understanding the mystery of the neutrino and its mass.