dark matter search carter hall, university of maryland
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DARK MATTER DARK MATTER SEARCHSEARCH
Carter Hall, University of MarylandCarter Hall, University of Maryland
Direct detection of WIMP dark matter
00 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
It’s not difficult to shield at 10 keV
typical WIMP recoil energies
Gamma interaction cross section
Only MeV ’s can penetrate,but only keV ’s can
fake a WIMP
Self-shielding of liquid xenon is extremely powerful
Fiducial volume cut rejects most backgrounds
Sensitivity improves quickly as target mass increases!Self-shielding effect
~MeV
~keVscatteringevent – forward
scattering
mustcross
full volumewithout
scatteringagain
Particle ID: nuclear recoil discrimination
Ionization-to-scintillation ratio allows discrimination between common radioactivity and WIMP events.
Background rejection factor of ~180
The Hunters HutThe Hunters Hut Homestake (SD)Homestake (SD)
2002 2002
Homestake Solar Neutrino Experiment
Davis Cavern @ Homestake, September 2009
Davis Cavern @ Homestake, March 2011
Gaitskell - Brown University / LUX
LUX Detector - Overview
Titanium Vessels
Dodecagonal field cage+ PTFE reflector panels
PMT holding copper plates
Counterweight
Feed-throughs for cables / pipesLN bath column
Radiation shield
49 cm
59 cm
Cathode grid
Anode 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 2010
Cryostat successfully cooled to liquid xenon temperature – May 2010
1.5 ppt Kr
open leak valve
New analytic technique to detect krypton at the part-per-trillion level
arXiv:1103.2714v1
Detect electronegative impurities at less than a part-per-billion
open leak valve,bypass gas purifier
flow through flow through gas purifiergas purifier
bypassbypassgas purifiergas purifier
Xe is constant due to cold trap
18 ppb N2
5 ppb O2
0.25 ppb CH4
close leakclose leakvalve to measurevalve to measure
backgroundsbackgrounds
~few ppm Ar
arXiv:1002.2742
Experiment to test removal of tritiated methane
Xe proportional tubefor tritium counting Xe purifier
• > 99.9% of CH3T removed in one pass• Liquid Xenon removal test in this summer
CH3T storage bottle
FE-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
dayEvaporate Liquid > Gas / Purification -> Re-condense Liquid
LUX dark matter sensitivity
Status: LUX is being now being tested on the surface at Homestake.Move underground in December 2011.
The LUX Collaboration
Richard Gaitskell PI, ProfessorSimon Fiorucci PostdocMonica Pangilinan PostdocLuiz de Viveiros Graduate StudentJeremy Chapman Graduate StudentCarlos Hernandez Faham Graduate StudentDavid Malling Graduate StudentJames Verbus Graduate Student
Brown XENON10, CDMS
Thomas Shutt PI, ProfessorDan Akerib ProfessorMike Dragowsky Research Associate ProfessorCarmen Carmona PostdocKen Clark PostdocKaren Gibson PostdocAdam Bradley Graduate StudentPatrick Phelps Graduate StudentChang Lee Graduate Student
Case Western SNO, Borexino, XENON10, CDMS
Bob Jacobsen ProfessorStu Loken ProfessorJim Siegrist ProfessorJoseph Rasson EngineerMia ihm Grad Student
Lawrence Berkeley + UC BerkeleySNO, KamLAND
Masahiro Morii ProfessorMichal Wlasenko Postdoc
Harvard BABAR, ATLAS
Adam Bernstein PI, Leader of Adv. Detectors GroupDennis Carr Senior EngineerKareem Kazkaz Staff PhysicistPeter Sorensen Postdoc
Lawrence Livermore XENON10
University of Maryland EXO
Xinhua Bai ProfessorMark Hanardt Undergraduate Student
Frank Wolfs ProfessorUdo Shroeder ProfessorWojtek Skutski Senior ScientistJan Toke Senior ScientistEryk Druszkiewicz Graduate Student
James White ProfessorRobert Webb ProfessorRachel Mannino Graduate StudentTyana Stiegler Graduate StudentClement Sofka Graduate Student
Mani Tripathi ProfessorRobert Svoboda ProfessorRichard Lander ProfessorBritt Hollbrook Senior EngineerJohn Thomson EngineerMatthew Szydagis PostdocJeremy Mock Graduate StudentMelinda Sweany Graduate StudentNick Walsh Graduate StudentMichael Woods Graduate Student
SD School of Mines
Texas A&M
UC Davis Double Chooz, CMS
ZEPLIN II
Carter Hall ProfessorDouglas Leonard Postdoc
Daniel McKinsey ProfessorJames Nikkel Research ScientistSidney Cahn Research ScientistAlexey Lyashenko PostdocEthan Bernard PostdocLouis Kastens Graduate StudentNicole Larsen Graduate Student
DongMing Mei ProfessorWengchang Xiang PostdocChao Zhang PostdocJason Spaans Graduate StudentXiaoyi Yang Graduate Student
University of Rochester
U. South Dakota
Yale
ZEPLIN II
Majorana, CLEAN-DEAP
XENON10, CLEAN-DEAP
IceCube
Collaboration meeting, Homestake, March 2010Collaboration meeting, Homestake, March 2010
Formed in 2007, fully funded DOE/NSF in 2008