LARICCHIA1	Positron and positronium interactions with matter
Type	Experimental
#students	2
Orientation	Why is the scientific problem of interest at all? Every charged particle in nature has a corresponding antimatter counterpart with the same mass and opposite charge. The apparent imbalance between matter and antimatter in our universe remains one of the major unanswered questions in physics and cosmology. Positrons (e+) are the antiparticles of electrons (e-) with which they annihilate in matter within less than a billionth of a second. Prior to this, however, e- and e+ may form the lightest-known atom positronium (Ps), sometimes referred to as an isotope of hydrogen, with half the binding energy. Although unstable against annihilation, the intrinsic lifetime of Ps (~ 10-10-10-7s) is relatively long on a typical atomic scale (~10-16 s) and at UCL we produce beams of these unusual atoms and study their interactions with ordinary matter.
How	How is the research going to shed light on the given problem?. In addition to their fundamental importance for the comprehension of the physical universe, the relevance of positrons and Ps to our everyday world encompasses materials science and medical applications
What	What is the specific thing that the student will do, and how does it fit inside the overall project? In this respect, the aim of the present research project is to advance knowledge on the interactions of positron and positronium with atomic and molecular systems and thus to explore particular aspects of fundamental antimatter-matter interactions. Of particular interest to this project are reactions resulting in ionization (with and without Ps formation/break-up and/or excitation).
Special Knowlegde
Supervisor	Prof. Gaetana Laricchia g.laricchia@ucl.ac.uk
References (optional)	Experimental Aspects of Ionization Studies by Positron and Positronium Impact G. Laricchia, D.A. Cooke, A. Kover and S.J. Brawley in "Fragmentation Processes Topics in Atomic and Molecular Physics" Colm T. Whelan (Ed.), Cambridge University Press, (2013) 116 Positronium Collision Physics G. Laricchia and H.R.J. Walters La Rivista del Nuovo Cimento 35 (2012) 305 http://en.sif.it/journals/ncr/econtents/2012/035/06 DOI: 10.1393/ncr/i2012-10077-6 Electron-Like Scattering of Positronium S. J. Brawley, S. Armitage, J. Beale, D. E. Leslie, A. I. Williams, and G. Laricchia Science 330 (2010) 789 Abstract Reprint Full Text DOI: 10.1126/science.1192322