World's most sensitive dark matter detector in the offing

A next-generation dark matter detector that will be at least 100 times more sensitive than its predecessor is on schedule to begin its deep-underground hunt for theoretical particles known as WIMPs, or weakly interacting massive particles.

WIMPs are among the top prospects for explaining dark matter, which comprises 85 per cent of all matter in the universe and is observed only through gravitational effects, researchers said.

The detector LUX-ZEPLIN (LZ) has received approval from the US Department of Energy for the project's overall scope, cost and schedule.

The latest approval step sets in motion the buildout of major components and the preparation of its nearly mile-deep lair at the Sanford Underground Research Facility (SURF) in San Diego.

The experiment is designed to tease out dark matter signals from within a chamber filled with 10 metric tonnes of purified liquid xenon, one of the rarest elements on Earth.

"Nobody looking for dark matter interactions with matter has so far convincingly seen anything, anywhere, which makes LZ more important than ever," said Murdock Gilchriese, LZ project director and physicist at the Lawrence Berkeley National Laboratory (Berkeley Lab).

"The nature of the dark matter, which comprises 85 per cent of all matter in the universe, is one of the most perplexing mysteries in all of contemporary science," said Harry Nelson, LZ spokesperson.

"Just as science has elucidated the nature of familiar matter - from the periodic table of elements to subatomic particles, including the recently discovered Higgs boson - the LZ project will lead science in testing one of the most attractive hypotheses for the nature of the dark matter," said Nelson, physics professor at University of California, Santa Barbara.

LZ is named for the merger of two dark matter detection experiments: the Large Underground Xenon experiment (LUX) and the UK-based ZonEd Proportional scintillation in Liquid Noble gases experiment (ZEPLIN).

LUX, a smaller liquid xenon-based underground experiment at SURF will be dismantled to make way for the new project.

"Liquid xenon has turned out to be a nearly magical substance for WIMP detection, as demonstrated by the sensitivities achieved by ZEPLIN and LUX," said Henrique Araujo from Imperial College London, who leads the project in the UK.

The SURF site shields the experiment from many particle types that are constantly showering down on the Earth's surface and would obscure the signals LZ is seeking.

Some previous and planned experiments that also use liquid xenon as the medium for dark-matter detection are helping to set the stage for LZ.