This is pretty interesting and has far reaching implications.
XENON100 is a tank filled with 161 kilograms of chilled liquid xenon buried beneath 1,400 meters of rock in the Gran Sasso Underground Laboratory in Italy. Cosmic rays, which can mimic the action of dark matter particles, can’t easily penetrate to that depth (SN: 8/28/10, p. 22). A dark matter particle striking a xenon nucleus causes it to recoil, prompting the emission of light and ionization. The ratio of the amount of light emitted to the amount of ionization indicates whether a particle of dark matter has been found.
Still, the experiment provides new limits on the strength with which dark matter particles interact with ordinary matter. The upper limit of the interaction strength is about one-tenth the best previous estimate, Lang says. There could even be a link between the strength of that interaction and two recent hints from Fermilab’s Tevatron suggesting a new elementary particle that would communicate a new type of force, Weiner says (SN Online: 4/6/11). And Aprile says she’s hopeful that once a full year’s worth of data from the XENON100 experiment is analyzed, her team can claim a true detection of a WIMP. She and her collaborators are also pursuing plans to build an even larger underground xenon experiment using a ton of the liquid.