SIMPLE (dark matter experiment)

SIMPLE (Superheated Instrument for Massive ParticLe Experiments) is an experiment search for direct evidence of dark matter. 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. The experiment is predominantly sensitive to spin-dependent interactions of weakly interacting massive particles (or WIMPs).

SIMPLE is an international collaboration with members from Portugal, France, and the United States.

Design

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 refrigerant, freon, is used as the active mass.

In effect, each droplet behaves as a miniature bubble chamber. Once a nucleation has occurred, the acoustic shock wave is picked up by microphones. Each acquired signal is then fully discriminated in terms of acoustic external noise, gel-associated noise and most recently particle discrimination. 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.

Results

The final phase II analysis was published in Physical Review Letters in 2012.^[1] Spin-dependeant cross section limits were set for light WIMPs.

References

• The SIMPLE Phase II dark matter search (2014)
• Fabrication and response of high concentration SIMPLE superheated droplet detectors with different liquids (2013)
• Final Analysis and Results of the Phase II SIMPLE Dark Matter Search (2012)
• Reply to Comment on First Results of the Phase II SIMPLE Dark Matter Search (2012)
• Comment on First Results of the Phase II SIMPLE Dark Matter Search (2012)
• First Results of the Phase II SIMPLE Dark Matter Search (2010)
• SIMPLE dark matter search results (2005)

External links

• SIMPLE experiment website

Dark matter
Forms of dark matter	Baryonic dark matter Cold dark matter Hot dark matter Light dark matter Mixed dark matter Warm dark matter Self-interacting dark matter Scalar field dark matter
Hypothetical particles	Axino Axion Dark photon Holeum LSP Minicharged particle Neutralino Sterile neutrino SIMP WIMP
Theories and objects	Cuspy halo problem Dark fluid Dark galaxy Dark matter halo Dark radiation Dark star Dwarf galaxy problem ELKO field Halo mass function Massive compact halo object Mirror matter Navarro–Frenk–White profile Scalar field dark matter
Search experiments	Direct detection ANAIS ArDM ADMX CDEX CDMS CoGeNT COUPP CRESST DAMA/LIBRA DAMA/NaI DarkSide DEAP DMTPC DRIFT EDELWEISS EURECA KIMS LUX LZ PandaX PICO SIMPLE UKDMC WARP XENON ZEPLIN-III Indirect detection AMS-02 ATIC CALET CAST DAMPE IceCube MOA OGLE PAMELA Other projects MultiDark PVLAS SNOLAB
Potential dark galaxies	HE0450-2958 HVC 127-41-330 Smith's Cloud VIRGOHI21
Related	Antimatter Dark energy Exotic matter Galaxy formation and evolution Illustris project