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Physicist Mike Crisler inspects the bubble chamber of the Chicagoland Observatory for Underground Particle Physics experiment. Credit: Fermilab
The COUPP collaboration lowered its bubble chamber into a tunnel on the Fermilab site on March 28, 2005. Moving the bubble chamber 350 feet underground significantly reduces the background due to cosmic rays. Credit: Fermilab
Physicist Andrew Sonnenschein works on the COUPP detector. Credit: Fermilab
COUPP uses a glass jar filled with about a liter of iodotrifluoromethane, a fire-extinguishing liquid also known as CF3I. Credit: COUPP collaboration.
COUPP uses a glass jar filled with about a liter of iodotrifluoromethane, a fire-extinguishing liquid also known as CF3I. The jar is inside a pressure vessel that controls the formation of bubbles in the CF3I. After cameras have recorded a bubble, the chamber is compressed to collapse the bubble, then re-expanded to make it sensitive again for the next particle hitting a nucleus. Credit: COUPP collaboration.
The left photo shows a sequence of bubbles created by multiple scattering of a neutron. WIMPs are expected to produce a single bubble as shown in the right photo. COUPP found no signals above background. Credit: COUPP collaboration.
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