Edinburgh Nuclear Physics Group Consolidated Grant Proposal

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Physics and Astronomy

Abstract

The research programme aims at understanding the processes that forge the elements in stars and the big bang and obtaining a deeper understanding of nuclear matter. This requires remarkable experiments underground that let us study reactions at the very low energies occurring in stars such as the sun, and with beams of radioactive nuclei to understand the reactions that take place in explosive events such as supernovae which occur at higher temperatures and involve unstable isotopes. The astrophysical origin of the elements heavier than iron remains a particular mystery - they may for example be produced in thermally pulsing stars, supernovae and merging neutron stars. Fusion reactions with neutrons play a vital role in producing these elements but we do not understand these reactions, and the properties of radioactive isotopes produced by them, well enough. We will study reactions with neutron beams and study the properties of highly neutron-rich nuclei existing very far from stability. The nature of matter in neutron stars themselves remains a mystery. These are like large nuclei but bound by the gravitational force rather than the strong force. We will perform measurements of the neutron skin which forms on the surface of nuclei with intense high energy photon beams. The neutron skin is a mini laboratory for neutron star matter and by accurately measuring its properties we can access new information on neutron star structure and cooling mechanisms. The nature of matter inside neutron star cores is a great mystery, and it has been suggested that matter containing strange quarks may be present - a remarkable hypothesis. Our experiments will test the nature of nuclear matter for the conditions found in neutron stars. There is evidence that quarks can exist as a group of 6, a hexaquark, and may even be present inside neutron stars and influence their properties. This is not something found in textbooks but the theory of the strong force, quantum chromo dynamics, allows this exotic possibility. We will perform experiments to provide stronger evidence for the existence of the hexaquark and probe its properties.

Planned Impact

This proposal outlines an exciting research programme to explore the origins of the
chemical elements, the impact of nuclear physics on the behaviour of exotic environments
such as neutron stars and provide our first detailed understanding of how large groups
of quarks might behave.

To achieve these research objectives we will need to use all of our decades of
collective expertise and knowledge and then - we will need to take the next step -
and develop new and better experimental techniques, methods and equipment.

It is in these new developments that we find opportunities to exploit our research
techniques and methods in different ways and widen their impact.

Detector technologies have been developed which could provide significantly improved
medical scanners - better quality images faster. This concept has now been patented
and a proposal is now being prepared to make this innovation commercially available.

Medical research has recently indicated that ultra-fast bursts of gamma rays may be
more effective at killing tumour cells than conventional, continuous sources of
gamma-rays. Detecting ultra-fast bursts of gamma-rays is difficult but we have
recently devised a new method to detect such bursts - can we use this
to enable the development of safe, controllable and effective therapy?

Advanced nuclear reactor designs provide increased efficiency, reliability and safety.
But these designs are critically dependent on a detailed understanding of how neutrons
interact with, for example, the materials used to build the reactor. How will these
materials age during reactor operation? Neutrons are also used to target tumours and
it is important to understand how to control and manage the impact of neutrons on
healthy tissue and maximise their effect on cancerous tissue. Our research at facilities
which produce high fluxes of neutrons will help us understand both of these issues.

The nuclear physics research programme provides excellent training opprtunities
for PhD students. The size and scope of nuclear physics experiments means that
PhD students must actively engage with all of the scientific and technical aspects
of the experiments from beam transport to the experimental target, to the analysis
and interpretation of experimental data, and all points in between. The research
programme produces young scientists with a wide range of scientific and technical
competencies with employment opportunities in industry, business and academia.

Publications

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Auranen K (2018) Superallowed a Decay to Doubly Magic ^{100}Sn. in Physical review letters

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Kahl D (2019) s-wave resonances for the 18F(p,$\alpha$a)15O reaction in novae in The European Physical Journal A

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Rasco B (2018) The ORNL analysis technique for extracting ß -delayed multi-neutron branching ratios with BRIKEN in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Saha S (2020) On the ß -detection efficiency of a combined Si and plastic stack detector for DESPEC in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment