Positrons are the antimatter version of electrons and so their fate in a matter world is ultimately to annihilate. However, prior to this, a positron may combine with an electron to form a matter-antimatter hybrid called positronium. This is akin to a hydrogen atom with the proton replaced by a positron. Fundamental to our understanding of the physical universe, positron and positronium are these days also acknowledged as being fantastically useful in practical applications such as probing material properties and medical diagnostics. However, there is still much that we do not know for sure about the details of the interactions of these particles with ordinary matter. For example if, in a collision with an atom or molecule, a positron captures an electron, in which directions is the positronium likely to travel and with what probability? More...
Published: Jun 17, 2015 12:35:19 PM
How light of different colours is absorbed by carbon dioxide (CO2) can now be accurately predicted using new calculations developed by a UCL-led team of scientists. This will help climate scientists studying Earth’s greenhouse gas emissions to better interpret data collected from satellites and ground stations measuring CO2. More...
Published: Jun 15, 2015 10:29:10 AM
New research from UCL has uncovered additional second laws of thermodynamics which complement the ordinary second law of thermodynamics, one of the most fundamental laws of nature. These new second laws are generally not noticeable except on very small scales, at which point, they become increasingly important. More...
Published: Feb 10, 2015 11:55:53 AM
Dr Gillian Peach
+44 (0) 20 7679 3482
I was an undergraduate and postgraduate at Royal Holloway College, University of London (1954-1960) graduating with a B.Sc in Mathematics in 1957 and a Ph.D in Theoretical Physics in 1961. Having been a Research Assistant at UCL, 1960-1965 and a Research Associate, University of Maryland, 1965-1966, I have been at UCL from 1966 onwards. I have been on the Editorial Board of Journal Physics B: Atomic, Molecular and Optical Physics and am currently Co-Chairman of the working group on line broadening for Commission 14 of the International Astronomical Union (IAU).
My research involves the theoretical study of atomic and molecular processes that occur in low-energy and ultracold physics and in stellar astrophysics. Current research topics include:
- Ultracold collisions between atoms confined in traps
- Low-energy atom-atom collisions and applications to spectral line broadening
- Pressure broadening of spectral lines emitted in intense laser fields
- Polarization of radiation emitted by collisionally excited atoms
- The fundamental three-body problem: two-dimensional R-matrix methods for two-electron atomic systems
This research programme is conducted in collaboration with research groups
in the UK, Australia and France.
Page last modified on 06 mar 07 17:38