Playing with Particles

Co-presented with the Professor Harry Messel International Science School (ISS) and the Science Foundation of Physics, Faculty of Science, University of Sydney

Professor Allan Clark
7 July, 2011

Large Hadron Collider

One of the ATLAS detectors

In a 27 kilometre-long circular tunnel beneath the Franco-Swiss border sits the world’s largest and most expensive physics experiment: the Large Hadron Collider, or LHC. This extraordinary feat of science and engineering aims to uncover some of the remaining secrets of our Universe, giving us a glimpse at the earliest moments after the Big Bang, and illuminating the very nature of the fundamental forces and particles that make up our world.

Professor Clark is Director of the Department of Nuclear and Particle Physics at the University of Geneva, where he works with the LHC's ATLAS detector group. In this talk he will outline the Standard Model, currently our best physical theory of matter and forces, before delving into the unknown to share some of the mysteries that remain in particle physics where our science breaks down– and how colliding particles together at close to the speed of light inside the Large Hadron Collider may help us find the answers.


Professor Allan Clark had his first course in particle physics in the 1960s, as an undergraduate at the University of Tasmania. At that time, particle physicists first suggested that nucleons were not indivisible, but were made up of quarks (and we know now of many other things). This was the start of a new period in the understanding of fundamental particles and their interactions. This sparked his interest and shaped his subsequent research activities.

Subsequent to his undergraduate studies at the University of Tasmania and his doctoral studies at the University of Oxford, Clark's research activities have concentrated on the collision of hadrons (mostly protons or anti-protons) at the highest possible energies, using particle accelerators. He has been a member of several experimental teams that have made major contributions to our understanding of particle interactions, for example the UA2 experiment that co-identified the W and Z bosons at the CERN proton-antiproton collider, the CDF experiment that identified the top quark at the Fermilab Tevatron proton-antiproton collider near Chicago, and the ATLAS experiment that is now collecting data at the CERN Large Hadron Collider in Geneva. His research at ATLAS aims to understand the limits and possible extensions of the so-called Standard Model of fundamental interactions.

In 1989 Clark was appointed Professor of Physics at the University of Geneva and since 1998 he has served as Director of the Department of Nuclear and Particle Physics. He has over the years served on many advisory panels, including the European Committee for Future Accelerators and the Swiss Institute of Particle Physics where he was the founding Chair.