The PICO-60 experiment was, at the time of operation, the largest bubble chamber constructed for the search of dark matter. To take a closer look at the location of the experiment follow this link and choose image 24 on the virtual reality tour of SNOLAB. 


Dark matter experiments are located in laboratories deep underground to minimize the detection of naturally occurring radiation at the surface. In addition, the PICO-60 experiment was surrounded by a water shield to absorb neutrons that are created in the rock surrounding the lab. It is therefore often very anticlimactic to visit a dark matter experiment in its underground location, as no active part of the experiment is visible and instead all you see is a large water tank. The image on this page show are from the construction phase when the inside of the experiment was accessible.


PICO-60 inside its water tank at SNOLAB.
PICO-60 rendering.

PICO-60 was initially filled with CF3I, claiming competitive spin-dependent and spin-independent limits in the parameter space of low mass dark matter (publications). Unlike PICO-2L, this larger detector was located in the ladder lab area of SNOLAB, fully submerged in a water tank, and took data from 2013 to May 2014. Between the summer of 2014 and 2016, data taking was suspended to allow the PICO-60 detector to be upgraded, cleaned, and refurbished.

Data taking resumed in 2016, but for run 2 the target was filled with C3F8 to improve the sensitivity to spin dependent dark matter interactions. In addition, improved camera coverage made it possible to run the detector with the full 53 litres of active mass. In the first run only two high speed/resolution cameras were installed, restricting the active volume to about 25 litres. The experiment was cleaned and re-assembled so that particulate contamination was reduced significantly. The results from the second run were published in 2017 and 2019 (publications).

PICO-60 was decommissioned after the end of the data taking in the summer of 2017. The water tank and location of the experiment are now used for the new “right-side-up” chamber, PICO-40L.

PICO-60. Single bubble event.
PICO-60. Multi-bubble event.