Page 21 - EUREKA! Fall 2017

Dark matter is by far the dominant stuff in

the universe, and we still have essentially no
clue what it is.

before they can solve a mystery that liked about it,” he says, “is that you’re the world are currently on the hunt
has been confounding physicists for required to understand some fairly for dark matter, including work at the Caption: top, below left, right
decades, Boulay and his collaborators simple concepts but there’s very little Large Hadron Collider near Geneva, etc Sustrum facea pa cus non
et fugit explat offictatia simus
— a group of more than 75 researchers memorization, which I was never the LUX underground experiment in pedi aliatec totati quatus
from 10 institutions in Canada, the very good at. So I always excelled in South Dakota, the XMASS project at solorerro dicil explit, nonse
U.K. and Mexico — must first address physics, because once you understand Japan’s Kamioka Observatory, and se endem iuritae preprorias
a seemingly endless string of details. a few basic concepts you can go a the IceCube Neutrino Observatory, a asi blatur si temposs itatur,
Today, up on that ladder, four months long way.” particle detector at the South Pole. toreribus rerrovitem quunt, si
tem ius, sende nisitincia cuptas
after the experiment was first fired Boulay earned an undergraduate But DEAP, which was conceived of eaque venditatus volenis
up in November 2016, Boulay and degree in physics at Laurentian around 2004, when Boulay was doing moloresto int. Photo: Luther Caverly
SNOLAB operations supervisor Tony University in Sudbury when the a post-doc at the Los Alamos National
Flower are trying to figure out how Sudbury Neutrino Observatory Laboratory in New Mexico, represents
to fix a bug in the cryogenic system. experiment was starting, exposing perhaps the best shot scientists have.
When it runs, as it is expected to him to particle physics, and stayed at Its potential is rooted in the unique
do for years, it vibrates, and that Laurentian for his master’s degree. He properties of argon, which will help
movement appears to be damaging got involved in the final assembly of researchers discriminate backgrounds
and loosening some of its components the SNO detector (see “SNO story,” when they study the recoil of
and fittings. page TK) while working toward his scattering particles, as well as the large
“This is typically of the lower-level PhD at Queen’s University, and had an volume of argon being deployed. Every
mechanical problems we’re sorting opportunity to analyze its first results. other component of the detector has
out,” says Boulay, DEAP’s project Then he zeroed in on the quest for an extremely low level of radioactivity,
director and a Canada Research Chair dark matter. which will allow the experiment
in Particle Astrophysics and Subatomic The term “dark matter” was coined to capitalize on the sensitivity of
Physics. “We’re certainly dealing with in the 1930s by Swiss astronomer its location deep underground at
a lot of technical and engineering Fritz Zwicky, who, according to the SNOLAB.
challenges, but the concept of a DEAP website, “determined the mass
particle scattering off a nucleus like a and velocity distributions of objects In 2006, Boulay led the development
billiard ball is fairly straightforward. At within the Coma galaxy cluster, and of a small prototype detector with
a fundamental level, what we’re doing found that the velocity distributions he liquid argon at Queen’s to demonstrate
is pretty simple, yet it’s one of the calculated implied the cluster had much that this process could work. That
biggest questions in particle physics, more mass than the observable light design, and expertise from the SNO
and maybe in science. suggested.” Forty years later, American experiment, informed the construction
“This is by far the dominant stuff astronomer Vera Rubin corroborated of the full-scale version. The argon
in the universe,” he says about dark the existence of dark matter by vessel, which has an inner radius of
matter, “and we still have essentially no studying the rotation of galaxies and 85 centimetres, is surrounded by
clue what it is.” concluding they “rotated too fast for 255 photomultiplier tubes (PMTs) to
the gravitational force of their visible capture the light pulses, and the whole
In a sense, Boulay was destined to stars to hold them together.” Her apparatus is immersed in a water tank
lead DEAP. He was born and raised results “pointed to the existence of vast to further block external radiation.
in Sturgeon Falls, an hour east amounts of unobservable mass, even Since it was turned on last November,
of Sudbury on the Trans-Canada 10 times more than visible, surrounding much of the focus at DEAP has been
Highway, and became interested in galaxies of stars.” calibrating the detector and collecting
physics at a young age. “The thing I Several dozen experiments around (continued on page 23)

20 science.carleton.ca Photo: science.carleton.ca 21 Photo: