The Cryogenic Low-Energy Astrophysics with Noble liquids (CLEAN) experiment by the DEAP/CLEAN collaboration is searching for

dark matter In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...

using

noble gases The noble gases (historically the inert gases, sometimes referred to as aerogens) are the members of group 18 of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and, in some cases, oganesson (Og) ...

at the SNOLAB underground facility. CLEAN has studied

neon Neon is a chemical element; it has symbol Ne and atomic number 10. It is the second noble gas in the periodic table. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with approximately two-thirds the density of ...

and

argon Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...

in the MicroCLEAN prototype, and running the MiniCLEAN detector to test a multi-ton design.

Design

Dark matter searches in isolated noble gas scintillators with

xenon Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

and argon have set limits on WIMP interactions, such as recent cross sections from LUX and

XENON Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

. Particles scattering in the target emit

photons A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that ...

detected by PMTs, identified via pulse shape discrimination developed on DEAP results. Shielding reduces the cosmic and radiation background. Neon has been studied as a clear, dense, low-background scintillator. CLEAN can use neon or argon and plans runs with both to study nuclear mass dependence of any WIMP signals.

Status

The MiniCLEAN detector will operate with argon in 2014. It will have 500 kg of noble cryogen in a spherical steel vessel with 92 PMTs shielded in a water tank with

muon A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of ''ħ'', but with a much greater mass. It is classified as a ...

rejection.

References

Experiments for dark matter search {{particle-stub