Two papers from EPSRC Fellow Dermot Green (CTAMOP) have appeared back-to-back(!) in the highly prestigious pages of Physical Review Letters. The papers Phys. Rev. Lett. 119, 203403 (2017) and Phys. Rev. Lett. 119, 203404 (2017) describe the processes of positron cooling and annihilation in room-temperature noble gases, simulated using accurate positron-atom data calculated with the many-body theory developed by the QUB Antimatter and Atomic Many-Body Theory Group led by Dr Gleb Gribakin and Dermot. 

 

The work has enabled the first simultaneous probing of the energy dependence of the positron scattering cross sections, annihilation rates and annihilation gamma spectra, has yielded the best description of long-standing experimental results to date, and has resolved outstanding “puzzles" in the field: e.g., establishing that the significant discrepancy between gas-cell and trap-based measurements of the “thermal” positron annihilation rate in Xenon is a result of the rapid annihilation of low-energy positrons leading to a quasi-steady-state positron momentum distribution that differs from the Maxwell-Boltzmann one. 

 

This international recognition follows the award to Dermot of the 2017 "Sheldon Datz Prize” for Outstanding Young Scientist attending the International Conference of Photonic, Electronic and Atomic Collisions (ICPEAC, the flagship international conference in atomic collision physics http://icpeac30.edu.au/prizes.php). The prize recognised Dermot’s internationally leading work in many-body theory of positron and positronium interactions with atoms and molecules, which has been developed at Queen’s in collaboration with Dr Gleb Gribakin (CTAMOP) and more recently also with Dr Andrew Swann (CTAMOP). Dermot received the award in the ‘Sheldon Datz prize’ plenary session of the conference in Cairns, Australia, where he was invited to present a special report on his work.