Edinburgh Nuclear Physics Consolidated Grant 2024-27

Our research program seeks to answer key open questions on the origin of the elements in stars, the processes responsible for stellar explosions, and the behaviour of nuclei at the limits of existence.

The experimental study of astrophysical reactions and nuclear properties requires cutting-edge instrumentation and suitable facilities for stable-, neutron-, and radioactive ion beams, as well as ion traps and decay spectrometers. The Group is uniquely well placed to exploit these capabilities at world-leading laboratories and has a strong track record in developing innovative instrumentation to match the unique requirements of different reaction- and nuclear properties studies.

Over the coming grant period we will initiate a program of reaction studies at the LUNA underground facility to investigate the origin of carbon, nitrogen, and oxygen isotopes in first-generation stars and to explore alternative neutron sources for the early synthesis of heavy elements. Also at LUNA, we will exploit the recent installation of a new 3.5MV accelerator to investigate open questions on the core metallicity of the Sun, carbon fusion in massive stars, and neutron source reactions for the slow-neutron capture process.

At the n_TOF (CERN) neutron beam facility, we will lead a rich program of neutron-induced reaction measurements, for example to explore the origin of radioactive 40K, believed to be responsible for heat generation in rocky exoplanets, elucidate the origin of rare pre-solar stardust grains with peculiar abundances of Si and S isotopes, and study the destruction of the cosmic gamma ray emitter 26Al in massive stars. We plan challenging neutron activation measurements on radioactive samples to help explain abundances of certain metal poor stars, and the origin of nature's rarest isotope 180mTa.

Also at CERN, we plan to improve on our previous investigations of 44Ti-destruction to shed light on the final stages of supernovae explosions of massive stars.

Storage rings will provide game-changing opportunities to study reactions with radioactive isotopes relevant to explosive astrophysical scenarios, by delivering both increased beam purity and intensities otherwise unavailable anywhere else in the world. At the Experimental Storage Ring at GSI we will explore the origin of some light p-nuclei, whose abundances are consistently underproduced by stellar models of core-collapse and type Ia supernovae.

The Group has approved experiments to exploit the recently commissioned Edinburgh-built CARME detection system at the CRYRING storage ring to study key reactions of novae explosions. With beamtime already approved at TRIUMF we will investigate reactions involved in the production of 18F, a main cosmic-ray emitter from novae, and in the break-out from the Hot-CNO cycle in X-ray bursts.

The Group has developed state of the art ion traps and radioactive decay detection systems to investigate masses and decay properties of exotic nuclei across wide areas of the nuclear landscape. Over the grant period, we will lead a program of high-precision mass measurements of neutron-rich light nuclei near closed shells as unique testbeds for modern nuclear theories.

Further mass measurements of neutron-rich heavy nuclei will provide constraints to explosive nucleosynthesis in the r-process. Such studies will be complemented at RIKEN by decay measurements of nuclei in the rare-earth region by exploiting unique experimental capabilities including the Edinburgh-built AIDA device.

Mass measurements near the proton-drip line will shed light on the limits of nuclear binding, while proton and alpha decay studies at Argonne will offer unique insights into the effect of nuclear shape on quantum tunnelling rates. With novel ion trapping devices developed in Edinburgh we will investigate exotic decay modes and radioactive molecules with potential for physics beyond the standard model and medical applications.