Research

My main research interests are in precision measurements that probe fundamental physics, especially searches for permanent electric dipole moments (EDMs) of atoms or particles.  A non-zero EDM would reveal a new source of CP-violation beyond the standard model, and possibly lead us closer to answering the question as to why there is so much more matter than antimatter in our universe.

Here at Sussex we are developing techniques to increase the magnitude of electric fields that can be applied in experiments looking to measure the neutron EDM (nEDM), since the sensitivity to the nEDM scales linearly with the size of the electric field in the neutron storage chamber. We are studying how to optimise the geometry of the electrodes and neutron storage chamber design in order to achieve higher electric fields, as well as studying high voltage breakdown in cryogenic liquides. The electric field can be increased by an order of magnitude beyond current levels if the nEDM measurement is performed in superfluid liquid helium.

Another key aspect of nEDM measurement is the precise control and understanding of the magnetic field environment where the neutrons are stored. Various optical atomic magnetometry systems are used to monitor the magnetic fields in the apparatus. We are developing a new system involving free precessing 3He spins read out by nearby Cs magnetometers that will give great improvements to the accuracy of the magnetic field evaluation. Optical atomic magnetometry may also be applied to sensing biomagnetic signals, such as MEG signals from the human brain.

Neutrinos potentially play a role in the matter-antimatter asymmetry question, since there is a possibility of CP violation being measured in neutrino oscillation. The DUNE experiment, based on a neutrino beam originating from Fermilab, measured by enormous liquid argon TPC detectors 1300 km away and 1 km underground, hopes to give the first detection of CP violation in the neutrino sector. The liquid argon TPC detectors require some of the same techniques that are also useful for cryogenic nEDM measurement, especially in terms of delivering very high voltages into cryogenic liquids. We are studying ways that the high voltage interacts with scintillation light collection systems that are planned for the DUNE detector.