Kenneth J. Ragan
Professor of Physics
B.Sc. (Alberta '80)
D.Sc. (Geneva '86)
Welcome to my home page. If you want to contact me for enquiries about
graduate work, my research, or any other subject, details can be found
at the bottom of this page.
If you're here to get information about PHYS 131, click
here!
For an overview of the McGill Astrophysics group's activities, click
here.
Research Interests
My major research interests are centred on my work at the
Fred Lawrence Whipple
Observatory of the SAO (Smithsonian Astrophysical Observatory),
where I'm involved with the
VERITAS collaboration.
Formerly, my major effort was
in Albuquerque, New Mexico, on the
STACEE
collaboration.
Both STACEE and VERITAS are
air Cherenkov
instruments, in which high energy
gamma-rays impinging on the upper atmosphere create showers of charged
secondary particles. These secondaries are energetic enough to be moving
faster than the (local!) speed of light in the upper atmosphere and so they
in turn emit Cherenkov light. Cherenkov light is the bluish emission that
is the electromagnetic equivalent of a sonic boom from a supersonic aircraft.
It is probably familar to you from the bluish glow visible in photographs
of stored spent nuclear fuel rods, where the emitted radiation
(electrons) emit the Cherenkov light in water.
In VERITAS (and previously, with the STACEE experiment) we detect the Cherenkov light at ground level even
though, by that point, the shower of secondary particles has been absorbed
high up in the atmosphere. Measuring the properties of the Cherenkov light (intensity
and direction) allows us to infer the direction and energy of the original
high energy gamma-ray, and thus to do gamma-ray astronomy.
STACEE was operated from 1996 to 2007 and
that used the wavefront-sampling technique to observe
astrophysical sources of high energy
gamma-rays. In particular, the gamma-ray energy range between about 40 GeV and 200 GeV
is an energy regime which is largely unexplored to date, and STACEE's goal was to
be sensitive to part of this range. Both lower energy
(space-based) and higher energy (ground-based) detectors have observed numerous sources,
primarily Active Galactic Nuclei (AGNs) and Supernova Remnants (SNRs), and
this energy regime is thought to be a crucial part of the effort to
understand the mechanisms powering these sources.
VERITAS' goals are similar, although the technique is quite different;
while STACEE was a wavefront sampling detector, VERITAS is
an array of four multiple imaging telescopes, each 12 m in size.
Individual imaging telescopes in
the gamma-ray regime have operated very successfully for many years
above an energy of about 250 GeV.
With multiple imaging telescopes, the sensitivity of the technique
increases (allowing us to see weaker gamma-ray sources) and the threshold energy
decreases (again allowing us to explore the 50 GeV to few-hundred GeV regime).
VERITAS is currently the world's most sensitive air Cherenkov instrument.
The McGill gamma-ray astrophysics research group
currently consists of two faculty (Prof. David Hanna and myself), a
post-doctoral researcher, three graduate students and an ever-changing number
of undergrad researchers!
I have other interests in the more traditional field of
accelerator-based particle physics,
in non-accelerator (underground) particle physics and particle astrophysics, and in
detector technology.
A full publication list is available here.
Teaching:
In 2024/2025, I will be teaching one freshman course:
is a calculus-based course in (surprise, surprise!) mechanics and waves, meant for freshman
students entering programs in Engineering or the physical sciences.
Interesting summer reading:
If you're in my course PHYS 131 in Fall 2024 (or in PHYS 101, which has very similar content but for the life-sciences streams) and are interested in the human
history of the development of Newton's ideas, you might want to check out "The Clockwork Universe"
by Edward Dolnick. We'll touch on many of these ideas in our course, but the book is
much more complete on the historical side (and less complete mathematically, of course) than we can possibly be. A great read!
Other teaching interests:
One of my interests is the development of new pedagogic approachs to undergraduate physics teaching, to enhance student conceptual learning. I'm a
member of SALTISE, a project funded
by the Quebec government to use technology and innovation to improve science education.
I am the recipient of the 2007 J.D. Jackson Award of Excellence in Teaching (given by the
Department of Physics), and was nominated by McGill for the 2009
National Technology Innovation Award (given by the
The Learning Partnership),
see here.
I was honoured with the Faculty of Science's 2011 Leo Yaffe Award for Excellence in Teaching, and the Principal's Prize for Excellence in Teaching in 2013.
Here is my keynote address at the 2009 McGill Workshop
on
"Learning to Teach" , hosted by the Faculty of Graduate and Postdoctoral Studies (GPS)
and Teaching and Learning Services (TLS) in November, 2009.
Older talks/presentations:
- Invited talk on Future Gamma Ray Detectors, given at the 2017 International School of Space Science "Cosmic Ray Physics in Space", June 2017, L'Aquila, Italy.
- An invited talk on recent VERITAS results given at the 2011 Rome International Conference on Astroparticle Physics (RICAP), Rome, May 2011.
- An introductory lecture on astro- and particle-physics for CEGEP students, March 2011.
- A seminar at the University of Texas (Austin), in January 2011;
- A non-specialist level talk for the STARS (Science Talks about Research for Staff) program at McGill, about astronomy without light,
February 2010;
- Colloquium at Queen's University,
April 2009;
-
Presentation in Faculty of Science series "Soup-n-Science", January 2008;
Journals and preprints:
On a lighter note:
Some of my favorite physics- (or science-)humour websites:
Ken Ragan Voice: (514) 398-6518
Physics Department Fax: 398-3733
McGill University
3600 University St.
Montreal, QC
Canada, H3A 2T8
The best way to contact me is electronically:
[email protected]