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DAMA/LIBRA is a dark matter particle detector at Laboratori Nazionali del Gran Sasso in Italy. The detector consisted of carefully shielded scintillators of sodium iodide crystals (NaI) doped with thallium expected to interact with WIMPs, along with photomultiplier tubes to sense the interactions. The aim is to detect a variation in the number of interactions that is related to Earth's speed passing through the Milky Way's dark matter, which would vary over the course of Earth's orbit around the Sun. Other types of particle interactions would be less likely to show this particular pattern. DAMA/LIBRA is a follow-on to a similar experiment, DAMA/NaI, the overall project termed the DAMA Project, DAMA for "dark matter". LIBRA is for "large sodium iodide bulk for rare processes".
Some positive signal, i.e., such a seasonal variation has been announced but is not fully accepted as dark-matter detection. The signal analysis is suspected as possibly generating the variation, and non-dark-matter explanations also seem plausible. The same signal in a second such detector far away from the first (e.g., in the manner that LIGO uses separated detectors) would remove some of the objections. SABRE (for "sodium-iodide with active background rejection") is a project deploying two separate improved detectors. The results are also being checked by two independent projects: ANAIS-112 and COSINE-100.