The Large Underground Xenon (LUX) dark matter
experiment, which operates beneath a mile
of rock at the Sanford Underground Research
Facility in the Black Hills of South Dakota,
has completed its search for the missing matter
of the universe.
At an international dark matter conference
(IDM 2016) in UK, LUX scientific collaborators
presented the results from the detector's
final 20-month run from October 2014 to May
2016
LUX's sensitivity far exceeded the original
expectations of the experiment, but yielded
no trace of a dark matter particle.
LUX's extreme sensitivity makes the team confident
that if dark matter particles had interacted
with the LUX's xenon target, the detector
would almost certainly have seen them.
These new limits on dark matter detection
will allow scientists to eliminate many potential
models for dark matter particles, offering
critical guidance for the next generation
of dark matter experiments.
Dark matter is thought to account for more
than four-fifths of the mass in the universe.
Scientists are confident of its existence
because the effects of its gravity can be
seen in the rotation of galaxies and in the
way light bends as it travels through the
universe, but experiments have yet to make
direct contact with a dark matter particle.
The LUX experiment was designed to look for
weakly interacting massive particles, or WIMPs,
the leading theoretical candidate for a dark
matter particle.
If the WIMP idea is correct, billions of these
particles pass through your hand every second,
and also through the Earth and everything
on it.
But because WIMPs interact so weakly with
ordinary matter, this ghostly traverse goes
entirely unnoticed.
The LUX detector consists of a third-of-a-ton
of cooled liquid xenon surrounded by powerful
sensors designed to detect the tiny flash
of light and electrical charge emitted if
a WIMP collides with a xenon atom within the
tank.
The detector's location at Sanford Lab beneath
a mile of rock, and inside a 72,000-gallon,
high-purity water tank, helps shield it from
cosmic rays and other radiation that would
interfere with a dark matter signal.
The 20-month run of LUX represents one of
the largest exposures ever collected by a
dark matter experiment.
