Direct detection Dark matter

direct detection experiments aim observe low-energy recoils (typically few kevs) of nuclei induced interactions particles of dark matter, (in theory) passing through earth. after such recoil nucleus emit energy e.g. scintillation light or phonons, detected sensitive apparatus. in order crucial maintain low background, , such experiments operate deep underground reduce interference cosmic rays. examples of underground laboratories house direct detection experiments include stawell mine, soudan mine, snolab underground laboratory @ sudbury, gran sasso national laboratory, canfranc underground laboratory, boulby underground laboratory, deep underground science , engineering laboratory , china jinping underground laboratory.

these experiments use either cryogenic or noble liquid detector technologies. cryogenic detectors operating @ temperatures below 100mk, detect heat produced when particle hits atom in crystal absorber such germanium. noble liquid detectors detect scintillation produced particle collision in liquid xenon or argon. cryogenic detector experiments include: cdms, cresst, edelweiss, eureca. noble liquid experiments include zeplin, xenon, deap, ardm, warp, darkside, pandax, , lux, large underground xenon experiment. both of these techniques focus on ability distinguish background particles (which predominantly scatter off electrons) dark matter particles (that scatter off nuclei). other experiments include simple , picasso.

currently there has been no well-established claim of dark matter detection direct detection experiment, leading instead strong upper limits on mass , interaction cross section nucleons of such dark matter particles. dama/nai , more recent dama/libra experimental collaborations claim have detected annual modulation in rate of events in detectors, claim due dark matter. results expectation earth orbits sun, velocity of detector relative dark matter halo vary small amount. claim far unconfirmed , in contradiction negative results other experiments such lux , supercdms.

a special case of direct detection experiments covers directional sensitivity. search strategy based on motion of solar system around galactic center. low pressure time projection chamber makes possible access information on recoiling tracks , constrain wimp-nucleus kinematics. wimps coming direction in sun travelling (roughly towards cygnus) may separated background, should isotropic. directional dark matter experiments include dmtpc, drift, newage , mimac.