Aug 4 – 8, 2015
America/Detroit timezone

World-leading Dark Matter Limits with PICO-2L and PICO-60

Aug 5, 2015, 4:54 PM
Michigan (Michigan League)


Michigan League

Cosmology and Dark Matter Experiment AstroParticle, Cosmology, Dark Matter Searches, and CMB


Orin Harris (Indiana University South Bend)


The PICO Collaboration, formed from the merger of the Chicago-based COUPP and the Canadian-based PICASSO experiments, uses bubble chambers to search for dark matter. Bubble chambers are a unique dark matter detector technology. They provide very high $~10^{10}$ intrinsic electron recoil rejection, the ability to switch nuclear targets, acoustic rejection of alpha events, simple data acquisition, and low construction costs. The PICO-2L bubble chamber exposed a heavily fluorinated C$_3$F$_8$ target fluid for 211.5 kg-days in the 2100 meter deep SNOLAB underground laboratory. In-situ measurements and measurements at the University of Montreal confirm the detector is sensitive to nuclear recoils with energies as low as 4 keV while maintaining excellent electron recoil and alpha rejection capabilities. A background of nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. Despite the background, these data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date. World-leading results are also reported for the PICO-60 bubble chamber, a scale-up of the COUPP4 bubble chamber operated with $CF_3I$ target fluid at the SNOLAB underground laboratory.
Oral or Poster Presentation Oral

Primary author

Orin Harris (Indiana University South Bend)


PICO Collaboration (PICO Collaboration)

Presentation materials