A proton beam fired at a hydrogen target reveals how the neutron—an unstable particle that cannot be studied directly—responds to electric and magnetic fields. The Manchester nuclear physics group is using these photon-scattering experiments to measure the polarisabilities that describe how the building blocks of matter deform under force. This work addresses a fundamental gap: physicists can calculate the strong force using quantum chromodynamics, but they cannot yet predict how neutrons behave in real experiments. Without these measurements, models of nuclear structure remain incomplete, limiting our understanding of everything from how stars forge elements to the energy balance inside a nuclear reactor. The research is primarily curiosity-driven fundamental science. If successful, it will provide the first reliable experimental constraints on neutron polarisabilities, sharpening the theoretical tools used across nuclear physics. That deeper understanding could eventually improve models for nuclear energy production, where precise neutron behaviour governs reactor efficiency and safety. It may also refine calculations of the Lamb shift in muonic atoms—a subtle quantum effect that tests the limits of the Standard Model. Past fundamental work on nuclear forces has already yielded unexpected applications in medical imaging and security scanning; this project lays similar groundwork for future breakthroughs.
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Nuclear Physics aims to understand the structure and dynamics of nuclear systems. It is the key to understanding the Universe from the first microseconds of its inception when the quark-gluon plasma prevailed, through its history of star and galaxy formation where nuclear reactions play an essential role both in the generation of energy and the creation of elements. The field also has applications that benefit society in diverse areas, from medicine and security to power production, and a strong impact on other fields of science. The Manchester group is part of the UK nuclear community which has devised a mode of operation that enables it to make leading edge contributions at an international level. Experimental work is performed at specific overseas facilities with focussed investment in the necessary instrumentation to carry out this work. Atomic nuclei are a unique quantal laboratory in which microscopic as well as mesoscopic features, driven by effective two-body and three-body forces, can be studied. They are complex many-body systems, but often display unexpected regularities and simple excitation patterns that arise from underlying shell structure, pairing and collective modes of excitation. Such properties are also exhibited by simpler mesoscopic systems (for example, metallic clusters, quantum dots, and atomic condensates) the understanding of which draws heavily on techniques developed and honed in nuclear physics. A fundamental challenge is to understand nuclear properties ab-initio from the interplay of the strong, weak, and electromagnetic forces between individual nucleons. In recent years, enormous progress has been made with such programmes for light nuclei. For heavier nuclei, shell, cluster and other beyond mean field many-body techniques, based on effective interactions, provide essential frameworks for correlating experimental data, yet still lack the refinement to reliably predict nuclear properties as one moves more than a few nucleons from well-studied stable nuclei. Experimental measurements are made using the techniques of transfer reactions, gamma-ray spectroscopy and measurements of hyperfine atomic effects using lasers. We also aim to make connections between the interactions of nucleons and the underlying theory that describes the strong force, Quantum Chromodynamics. Key quantities are the polarisabilities that describe how the structures of nucleons respond to external electric and magnetic fields. We are developing theoretical tools to determine these from experiments on the scattering of photons from hydrogen and other light nuclei. The latter are needed to learn about the the properties of the neutron since it is an unstable particle, and are also interesting for the testing of nuclear forces in few-body systems and for the calculation of muonic atom Lamb shifts.
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