2019 Bates Prize winner

Achievement

Dr Green is an excellent young theorist in atomic and molecular physics. His main achievement is the development of many-body-theory computational approaches for low-energy positron scattering and annihilation in atoms.

This has led to a complete understanding of the whole body of experimental data for positron interaction with noble-gas atoms. It includes the elastic scattering cross sections, annihilation rates and annihilation gamma-ray spectra.

Challenging

Positron interaction with a many-electron atoms is a very challenging theoretical problem. This is because of the role played by the correlated motion of the positron and atomic electrons.

The correlations have an overwhelming effect on the positron-atom scattering and annihilation, producing orders-of-magnitude enhancements of the relevant characteristics.

The approach pursued by Dr Green has enabled to fully account for these effects and predict the scattering cross sections, annihilation rates and gamma-ray spectra, and positron thermalisation rates for noble gases. This is in complete agreement with experimental data, some of which remained poorly understood for decades.

Implications

This understanding and the many-body-theory methods used by Dr Green have important implications for the much more difficult problem of positron annihilation in molecules, and for numerous applications of positron annihilation in condensed-matter spectroscopies and positron emission tomography (PET).

The success in solving the positron-atom problem has also opened the prospect of developing a similarly accurate theory for the interaction of positronium (an electron-positron-bound complex) with many-electron atoms.

A recent work, Many-Body Theory for Positronium-Atom Interactions, co-authored by Dr Green, with AR Swann and GF Gribakin, was published in Physical Review Letters in 2018. It demonstrated the strength of this approach by performing the first accurate calculations of pickoff annihilation rates (where the positron annihilates with an atomic electron) for positronium collisions on helium and neon.

Versatility

A versatile theorist, Dr Green has also made important contributions to distinct fields beyond antimatter-atom interactions.

Notably, he solved the fundamental problem of the motion of an electron in an ultra-intense laser field, taking into account the key effect of photon emission, and he predicted the emergence of quantum chaos in cold collisions involving simple atomic and molecular systems.

Publications

Evidence of Dr Green's high-calibre work and international standing is reflected in a number of key publications in leading international journals. These include:

• five papers published in Physical Review Letters since 2014
• three papers published since 2017
• two single-authored publications

Research and conferences

Dr Dermot has been awarded several internationally competitive research fellowships. Most recently he received a prestigious European Research Council starting grant.

He is often invited to international conferences.

Prizes

Dr Dermot has won a number of prizes, which include:

• The 2017 international Sheldon Datz Prize for outstanding young atomic physicist, awarded at the International Conference on Photonic, Electronic, and Atomic Collisions (ICPEAC).
• The 2010 Institute of Physics, Ireland, Rosse Medal for physics communication.
• The 2018 Queen’s University Belfast Vice-chancellor's Research Prize.

Education and roles

2015-2019 

Engineering and Physical Sciences Research Council (EPSRC) Fellow at Queen's University Belfast.

2018

Reader in Theoretical Physics at Queen's University Belfast where he is now a group leader and holds a European Research Council Starting Grant.

2013-2015

Research Fellow in theory of ultra-cold molecules at Durham University.

2012

Research Fellow in strong-field quantum electrodynamics at Queen's University Belfast.

2011

PhD in theoretical atomic physics from Queen's University Belfast.

2010

Visiting Fellowship at Harvard University.

2008

A first-generation university student, Dr Green graduated with a first-class MPhys from the University of Oxford (Balliol College).

Advocacy

Beyond developing his research, Dr Green advocates for the physics community as:

• Treasurer of the Institute of Physics, Ireland
• a committee member of the Institute of Physics, UK, Atomic and Molecular Interactions Group
• a member of the international scientific advisory board for the International Workshop on Positron and Positronium Physics

Bates Prize

Learn more about the Bates Prize, awarded by five IOP special interest groups.