Abstract
Bubble chambers were the dominant technology used for particle detection
in accelerator experiments for several decades, eventually falling
into disuse with the advent of other techniques. We report here on
a new application for these devices. We operated an ultraclean, room-temperature
bubble chamber containing 1.5 kilograms of superheated CF3I, a target
maximally sensitive to spin-dependent and -independent weakly interacting
massive particle (WIMP) couplings. An extreme intrinsic insensitivity
to the backgrounds that commonly limit direct searches for dark matter
was measured in this device under operating conditions leading to
the detection of low-energy nuclear recoils like those expected from
WIMPs. Improved limits on the spin-dependent WIMP-proton scattering
cross section were extracted during our experiments, excluding this
type of coupling as a possible explanation for a recent claim of
particle dark-matter detection.
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