UCL Department of Physics and Astronomy


Prof David Cassidy

Professor of Experimental Physics

Dept of Physics & Astronomy

Faculty of Maths & Physical Sciences

Joined UCL
1st Apr 2012

Research summary

My undergraduate degree was in Physics with Astrophysics from Royal Holloway College in 1995, after which I moved to University College London for my PhD in experimental positron physics under the supervision of Professor Michael Charlton. After finishing my doctorate in 1998 I became a postdoctoral research fellow at Harvard University in the United States, and worked on experiments to do with positron channeling in gold crystals, and also nuclear excitation of Indium by positron annihilation, using accelerators at Lawrence Livermore National Laboratory in California. After spending a year at Washington State University I moved to the University of California, Riverside in 2002 to work with Professor Allen Mills on experiments involving positron trapping, and the production of intense positron pulses. In 2012 I was appointed a lectureship at University College London.

My research interests continue to be informed by the use of positron trapping technology. The physics of single component (i.e. charged) plasmas is of fundamental interest, and also has a direct application to the formation of high density positron pulses. These can then be used to produce relatively high densities of positronium, a metastable elelctron-positron system. Moreover, the generation of sub nano-second pulses of positronium atoms makes it possible to study these short-lived atoms probed with lasers and greatly facilitates a wide range of atomic spectroscopic measurements involving positronium. At high densities one may even create positronium molecules, and perform spectroscopy on them. I am presently interested in creating long-lived Rydberg states of positronium that can be used in a free-fall gravity experiment; this is interesting because to date there has never been any measurement of gravity involving antimatter.