DARK MATTER SEARCH Carter Hall, University of Maryland
Direct detection of WIMP dark matter~ 300 proton massesper liter of space.
If MWIMP ~ 100 GeV,then 3 WIMP/liter.
Typical orbital velocity~ 230 km/sec, or 0.1% speed of light.
Coherent scaler interactions:~ A2
Rate < 1 event / kg / 100 days, or much, much lower
Its not difficult to shield at 10 keVtypical WIMP recoil energiesGamma interaction cross sectionOnly MeV gs can penetrate,but only keV gs can fake a WIMP
Self-shielding of liquid xenon is extremely powerfulFiducial volume cut rejects most backgrounds
Sensitivity improves quickly as target mass increases!Self-shielding effect~MeV g~keVscatteringevent forwardscatteringmustcross full volumewithoutscatteringagain
Particle ID: nuclear recoil discriminationIonization-to-scintillation ratio allows discrimination between common radioactivity and WIMP events.Background rejection factor of ~180
The Hunters HutHomestake (SD)
2002 Homestake Solar Neutrino Experiment
Davis Cavern @ Homestake, September 2009
Davis Cavern @ Homestake, March 2011
LUX Detector - OverviewGaitskell - Brown University / LUXTitanium VesselsDodecagonal field cage + PTFE reflector panelsPMT holding copper platesCounterweightFeed-throughs for cables / pipesLN bath columnRadiation shield49 cm59 cmCathode gridAnode grid
LUX Surface Facility @ Homestake
LUX 350 kg detector under assembly
LUX 350 kg detector under assembly
Test deployment of LUX in the Surface Facility Water Tank April 2010
Test deployment of LUX in the Surface Facility Water Tank April 2010Cryostat successfully cooled to liquid xenon temperature May 2010
New analytic technique to detect krypton at the part-per-trillion levelarXiv:1103.2714v1
Detect electronegative impurities at less than a part-per-billionopen leak valve,bypass gas purifierflow through gas purifierbypassgas purifierXe is constant due to cold trap18 ppb N25 ppb O20.25 ppb CH4close leakvalve to measurebackgrounds~few ppm ArarXiv:1002.2742
Experiment to test removal of tritiated methaneXe proportional tubefor tritium countingXe purifier > 99.9% of CH3T removed in one pass Liquid Xenon removal test in this summerCH3T storage bottleFE-55 x-raycalibration
Thermosyphon cooling system
Xenon Purity measured in a 60 kg test run ~9 hr time constant for purification
> 2 m electron drift length achieved (> 1000 us) with 60kg target
Errors dominated by use of 5 cm test cell drift within large cryostat
0.2 tonnes circulation per day
Heat Exchanger Operates >96% EfficientDemonstrated - 18 W required to circulate 0.4 tonnes of Xe a day Evaporate Liquid > Gas / Purification -> Re-condense Liquid
LUX dark matter sensitivityStatus: LUX is being now being tested on the surface at Homestake.Move underground in December 2011.
The LUX CollaborationBrownXENON10, CDMSCase WesternSNO, Borexino, XENON10, CDMSLawrence Berkeley + UC BerkeleySNO, KamLANDHarvardBABAR, ATLASLawrence LivermoreXENON10University of MarylandEXOSD School of MinesTexas A&MUC DavisDouble Chooz, CMSZEPLIN IIUniversity of RochesterU. South DakotaYaleZEPLIN IIMajorana, CLEAN-DEAPXENON10, CLEAN-DEAPIceCubeCollaboration meeting, Homestake, March 2010Formed in 2007, fully funded DOE/NSF in 2008
Richard GaitskellPI, ProfessorSimon FiorucciPostdocMonica PangilinanPostdocLuiz de ViveirosGraduate StudentJeremy ChapmanGraduate StudentCarlos Hernandez FahamGraduate StudentDavid MallingGraduate StudentJames VerbusGraduate Student
Thomas ShuttPI, ProfessorDan AkeribProfessorMike DragowskyResearch Associate ProfessorCarmen CarmonaPostdocKen ClarkPostdocKaren GibsonPostdocAdam BradleyGraduate StudentPatrick PhelpsGraduate StudentChang LeeGraduate Student
Bob JacobsenProfessorStu LokenProfessorJim SiegristProfessorJoseph RassonEngineerMia ihmGrad Student
Masahiro MoriiProfessorMichal WlasenkoPostdoc
Adam BernsteinPI, Leader of Adv. Detectors GroupDennis CarrSenior EngineerKareem KazkazStaff PhysicistPeter SorensenPostdoc
Xinhua BaiProfessorMark HanardtUndergraduate Student
Frank WolfsProfessorUdo ShroederProfessorWojtek SkutskiSenior ScientistJan TokeSenior ScientistEryk DruszkiewiczGraduate Student
James WhiteProfessorRobert WebbProfessorRachel ManninoGraduate StudentTyana StieglerGraduate StudentClement SofkaGraduate Student
Mani TripathiProfessorRobert SvobodaProfessorRichard LanderProfessorBritt HollbrookSenior EngineerJohn ThomsonEngineerMatthew SzydagisPostdocJeremy MockGraduate StudentMelinda SweanyGraduate StudentNick WalshGraduate StudentMichael WoodsGraduate Student
Carter HallProfessorDouglas LeonardPostdoc
Daniel McKinseyProfessorJames NikkelResearch ScientistSidney CahnResearch ScientistAlexey LyashenkoPostdocEthan BernardPostdocLouis KastensGraduate StudentNicole LarsenGraduate Student
DongMing MeiProfessorWengchang XiangPostdocChao ZhangPostdocJason SpaansGraduate StudentXiaoyi YangGraduate Student