It is located in a 61 m3 cavern at the 500 level of the Laboratoire Souterrain à Bas Bruit (LSBB) near Apt in southern France.
SIMPLE is an international collaboration with members from Portugal, France, and the United States.
The SIMPLE detector is based on superheated droplet detectors (SDDs), a suspension of 1–2% superheated liquid C2ClF5 droplets (~30 μm radius) in a viscoelastic 900 ml gel matrix, which undergo transitions to the gas phase upon energy deposition by incident radiation.
The detectors are typically operated at ~200 kPa and ~280 K. Due to the construction technique, SSDs are almost insensitive to background radiation, and their sensitivity can be adjusted by controlling the temperature and pressure of each device.
The final phase II analysis was published in Physical Review Letters in 2012.