B.Sc. (McGill '75)
Ph.D. (Harvard '80)
W.C. Macdonald Professor of Physics
My research interests are in experimental high energy physics at both ends of the distance scale; I have worked in particle physics at accelerator laboratories and am now participating in a program of ground based gamma ray astronomy. Very recently I have developed an interest in cosmology and am now contributing to an experiment to measure the effects of dark energy on the expansion history of the Universe.
I began my research career in Geneva, Switzerland at the CERN Intersecting Storage Rings where I did my thesis experiment (R606) studying proton-proton collisions. Following that I did postdoctoral work at the same accelerator but with a different detector (R110).
After joining the McGill Physics Department I worked for many years in the ZEUS collaboration at the DESY laboratory in Hamburg, Germany. ZEUS was an experiment in which electron-proton collisions are studied.
My current research is in astrophysics. I was a founding member of the STACEE collaboration. We constructed a detector which used Cherenkov light from high energy showers to detect gamma rays in the energy range 100 < E < 1000 GeV. This detector was built using the heliostats at a solar power research facility in New Mexico. It was a cheap way to get a very large mirror for collecting the Cherenkov photons. We ran STACEE between 1999 and 2007 and produced some nice results and some great students but, as better detectors such as VERITAS came on line, it was time to shut it down.
Currently I am a member of the VERITAS collaboration. We are operating a third-generation detector for gamma rays on the lower slopes of Mount Hopkins in Arizona. The detector comprises an array of four 12-metre diameter imaging telescopes. We can detect gamma rays with energies from about 100 GeV to beyond 10 TeV. You can read about it in a CERN Courier article that I wrote.
I am also a member of the CHIME collaboration. We are building a giant radio telescope to measure Baryon Acoustic Oscillations in the red shift range 0.8 < z < 2.5. This is the period during which dark energy began to control the expansion rate of the Universe. CHIME will comprise four parabolic cylinders, each 20 wide and 100 m long and sensitive to radio waves with frequencies between 400 MHz and 800 MHz. The idea is to map neutral hydrogen by detecting its 21-cm emission. The BAO signature will show up in the data and can be used as a 'standard ruler' to measure the expansion history of the Universe.
I enjoy building detectors and have produced several components and calibration systems for the ZEUS detector as well as a significant fraction of the STACEE apparatus. I continued this practice on the VERITAS project. I also do projects which are purely instrumentation research. For example I was a founding member of a collaboration that developed a Compton-Imager, a telescope that is used to detect gamma-rays in the 100 keV to 1 MeV range and will be used in safety and security applications.