Page 19 - EUREKA! Fall 2017

NEW

WINDOW

ON THE

UNIVERSE

DEAP-3600 AND THE

SEARCH FOR DARK MATTER

By Dan Rubinstein
Photos by Luther Caverly

n a cramped passageway that leads to SNOLAB’s cavernous Cube Hall,
Carleton physics professor Mark Boulay climbs a stepladder to inspect a
Icooling system built around a 3,000-litre tank of liquid nitrogen. The constant
supply of cryogenic nitrogen is fed downward through a series of tubes and
apertures to a two-inch-thick spherical acrylic vessel, where it keeps 3.6 tonnes
of argon in liquid form at a temperature of about -180 Celsius. That argon is the
core of the DEAP-3600 experiment — an attempt to detect an invisible substance
Mil mossus. Ro
elliquis qui volessitaes known as dark matter, which is thought to account for roughly one-quarter of the
doluptaquas universe’s energy density. Dark matter is believed to outweigh normal matter (the
expernatum si destrum atoms we are familiar with) by a factor of five to one, even though its existence
sit omnimuscia has so far only been inferred by its gravitational effects on stars and galaxies and
iusdae. Am nos aut other indirect measurements.
ma voloribus et
optatia denderro berit With the two kilometres of rock overhead blocking most of the cosmic
facimag niminci liquae radiation that reaches the planet, and with 10 times more sensitivity than any
nonsequ atemperspit other comparable experiment, the DEAP detector could allow scientists to
exerruntenis quid observe and identify dark matter by tracking the faint light pulses that result from
quam qui abor minctor
eperfero eseniaesti Photo: the elastic scattering of dark matter particles when they hit argon nuclei. But

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