Following the success of the second run of PICO-60, the PICO collaboration re-designed the bubble chamber technology to improve background suppression in the continued search for dark matter. The new system involves two concentric quartz jars, orientated “right-side-up”, when compared to PICO-60. The advantage is the new inner jar eliminates the need for a buffer liquid (water region isolating the stainless-steel components from the target volume), which appeared largely responsible for the backgrounds observed in run 1. The new design also incorporates a newly engineered thermal system, which allows more stringent control over operating conditions that determine the energy threshold of the detector.
The detector began construction at SNOLAB in 2019 and was finished in 2020. Currently the new systems of the detector are being commissioned, stay tuned for new updates in 2021.
The above single bubble event was captured during the commissioning of the pressure system.