PICO.jpeg The PICO Collaboration (formed from the merger of two existing groups, PICASSO and COUPP) uses bubble chambers to search for galactic dark matter. The detectors consist of a fused-silica jar sealed to a flexible, stainless steel bellows, all immersed in a pressure vessel filled with hydraulic fluid. The jar is filled with a refrigerant that is superheated, so when a particle hits it, some of the refrigerant boils and forms a bubble. The bubbles are captured on camera, and 'heard' by piezos. When a bubble is detected the bellows compress to re-pressurize the refrigerant and prevent it all from boiling.

PICO-2L and PICO-60 were the first two iterations of the detector and have both finished their data-taking runs and been decomissioned. PICO-40 is currently commissioning at SNOLAB, and once the water shielding tank is full it will begin calibration data runs. PICO-500 is another scaled-up version of the detector (jumping from 40 L of target material to 350 L) which is in development and currently sourcing materials and components. It will eventually be installed in the Cube Hall at SNOLAB.

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