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
Professor Peter Barker
I have a background in atomic and molecular laser spectroscopy, non-linear optics, and laser trapping and cooling. Within the last 10 years my research has concentrated on the study of molecular cooling and trapping and on quantum cavity optomechanics. I have expertise in developing applications from more basic optical physics research. I was awarded a PhD in Physics from the University of Queensland, Australia in 1996. From 1997 to 2001 I was a Postdoctoral Research Associate, and then a Research Scientist and Lecturer in the Applied Physics Group in the Mechanical and Aerospace Engineering Department at Princeton University. At Princeton, I began to study the manipulation of atoms and molecules in pulsed optical fields by studying coherent Rayleigh scattering from molecules trapped in optical lattices. During this time I was part of a multidisciplinary team of physicists and engineers from Princeton University, Sandia National Laboratories and Lawrence Livermore developing a new type of wind tunnel for accelerating gases to hypersonic speeds using lasers and electron beams. In 2001 I took up the position of Lecturer in the Physics Department at Heriot-Watt University and became a Senior Lecturer in 2004. In October 2006 I joined the AMOP group at UCL as a Reader and was promoted to Professor in October 2007. Currently I have projects in cavity optomechanics using nanoparticles levitated in vacuum and larger microscale clamped systems based on whispering gallery mode resonators for studying fundamental quantum mechanics and for development of sensors.
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