Nuclear Physics Consolidated Grant

The majority of the visible mass of the universe is made up of atomic nuclei that lie at the centre of atoms. Nuclear physics seeks to answer fundamental questions such as: "How do the laws of physics work when driven to the extremes? What are the fundamental constituents and fabric of the universe and how do they interact? How did the universe begin and how is it evolving? What is the nature of nuclear and hadronic matter?" The aim of our research is to study the properties of atomic nuclei and to measure the properties of hot nuclear matter in order to answer these questions. No one yet knows how heavy a nucleus can be; in other words, just how many neutrons and protons can be made to bind together. We will study the heaviest nuclei that can be made in the laboratory and determine their properties which will allow better predictions to be made for the "superheavies". For lighter nuclei we will explore in the region of the proton and neutron drip lines, which are the borders between bound and unbound nuclei. We will determine more precisely than ever before the location of these drip lines. Nuclei beyond the proton drip line have so much electrical charge that they are highly unstable and try to achieve greater stability through the process of proton emission. We will investigate how nuclear behaviour is affected when protons become unbound.

For these exotic systems we will also explore how the nucleus prefers to rearrange its shape, which can be a sphere, rugby ball, pear, etc. and how it stores its energy among the possible degrees of freedom. We will also investigate how the properties of these nuclei develop as we make them spin faster and faster. We will try to determine the precise nature of ultra high spin states in heavy nuclei, just before the nucleus breaks up due to fission. By violently removing a nucleon from a nucleus in a nuclear reaction at high energies and measuring its properties, we can investigate to what extent the nucleon "feels" the influence of its neighbouring nucleons, whether it is correlated with them. Such information tells us about the nuclear force inside the nucleus at different inter-nucleon distances. Nuclear matter can exist in different phases, analogous to the solid, liquid, gas and plasma phases in ordinary substances. By varying the temperature, density or pressure, nuclear matter can undergo a transition from one phase to another. In extreme conditions of density and temperature (about 100 thousands times more than the temperature at the heart of the sun!), a phase transition should occur and quarks and gluons (of which the protons and neutrons are made of) should exist in a new state of matter called the Quark-Gluon Plasma. By colliding nuclei together at high energies at the Large Hadron Collider at CERN, we will study properties of this new state of matter. Such information is not only important for nuclear physics but also to understand neutron stars and other compact astrophysical objects.

This programme of research will employ a large variety of experimental methods to probe many aspects of nuclear structure and the phases of strongly interacting matter, mostly using instrumentation that we have constructed at several world-leading accelerator laboratories. The work will require a series of related experiments at a range of facilities in order for us to gain an insight into the answers to the questions posed above. These experiments will help theorists to refine and test their calculations that have attempted to predict the properties of nuclei and nuclear matter, often with widely differing results. The resolution of this problem will help us to describe complex many-body nuclear systems and better understand conditions in our universe a few fractions of a second after the big bang.

Nuclear physics research and technology development has had a huge beneficial influence in our Society. Through low-carbon energy production, radiation detection for national security or environmental monitoring and cancer diagnosis and treatment in modern healthcare, the applications emerging from nuclear physics are numerous.

Recent high-profile scientific discoveries include:
- The confirmation of the existence of the superheavy chemical element 117, which was an APS top 10 physics news story in 2014. In collaboration with Lund and GSI, researchers from Liverpool demonstrated a way to identify new elements directly. This led to element 117 being named tennessine in 2016.
- ISOLDE was used to study the shape of the short-lived isotopes 220Rn and 224Ra. The data show that while 224Ra is pear shaped, 220Rn vibrates about this shape. The results of the Liverpool-led measurements, that also have implications for atomic EDM measurements, was selected as a top 10 breakthrough in physics by Physics World in 2013 and continues to receive strong interest from the media world-wide.
- The work at ultra-high spin in nuclei has been cited as one of the Science highlights of 2013 and in the major 2012 decadal report "Nuclear Physics: Exploring the Heart of Matter" and more recently as an article in the journal celebrating the Bohr, Mottelson and Rainwater Nobel prize.
- The ALICE measurement of the mass difference between 2H/anti-2H and 3He/anti-3He nuclei was published in Nature with a video summary and received attention in the international news media. Article metrics show that this paper was in the top 1% for online attention.

The University of Liverpool has significant industrial engagement programmes that support knowledge exchange and the development of future REF returnable impact cases with a focus on nuclear measurement techniques and instrumentation. Industrial collaborators include AWE, Canberra, Kromek, Ametek, John Caunt Scientific, Metropolitan Police, MoD, National Nuclear Laboratory, Rapiscan, Sellafield Ltd. and a large number of NHS Trusts.

The University Department of Physics is one of only three national training providers for the Modernising Scientific Careers Clinical Science (Medical Physics) MSc, funded by the NHS. This provides a unique opportunity to build collaborative research and Continuing Professional Development partnerships within the Healthcare sector.

Beyond satisfying human curiosity around the workings of nature, pure research in nuclear physics has also tremendous societal impact. The University of Liverpool has an excellent track record in public engagement and outreach in a subject that has a natural fascination for the public. Indeed, it fulfils the important role of educating the public in nuclear radiation and its wider aspects, both positive and negative and is important to drive interest in the study of STEM subjects. Nuclear Physicists are frequently invited to share their knowledge and talk about their research at schools, science festivals and community groups.

The University of Liverpool hosts the state-of-the-art Central Teaching Laboratory (CTL) facility. The CTL has a dedicated laboratory for Nuclear Physics and radiation measurements and schools and outreach activities will be held on a regular basis with University support. In November 2016 the CTL will host a Science Jamboree for 300 Cubs, Beavers and Brownies. We also plan a family day in the CTL with the aim of improving knowledge of both nuclear physics research and applications in energy, security and healthcare.

The Liverpool group has an extensive list of media interactions. In particular Professor Butler and Dr Harkness-Brennan have contributed to BBC TV and Radio broadcasts and have recorded Podcasts and other online resources for public engagement. The ALICE experiment featured prominently in the recent BBC production presented by Jim Al-Khalili on The Beginning and End on the Universe.