Search for WIMPsBeatriz E. Burrola GabilondoApril 19, 2007The dark matter problemhttp://physics33.creighton.edu/faculty/duda/dark_matter.htmhttp://www.geocities.com/newastronomy/Chapter13.htmWhat are WIMPs?Weakly Interacting Massive ParticlesMassive – because we have not seen them in our particle accelerators yetWeakly interacting – in agreement with galaxy formationMost popular candidate:l NeutralinosHow do we plan on detecting them?Indirect methodsl Detect products (neutrinos, gammas) of WIMP decay that happens in the sunDirect methodsl Detect signature WIMP interaction with matter, orl Detect signature annual modulation due to WIMP halo presenceSolar capturehttp://amanda.uci.edu/results.htmlDirect detection methodsScintillating materialsPhonons in Ge or SiWIMPPhononsDetectorWIMPLightNaIXeArExperiments around the worldCDMSCOUPPCRESSTDAMAWARPEDELWEISSHDMSZEPLINAnnual modulationhttp://pppa.group.shef.ac.uk/dm/images/earth_in_galaxy.gif0DAMA results‘Single hit’ rateLow energyCosine-like behaviorOne year periodPhase at 2 JuneCDMSIIWIMPPhononsDetectorOther particlesThe CDMSII detectorsGe or Si ZIP detector148 arrays of 28 QETs eachSuperconducting aluminum collection finsTungstenThe CDMSII veto systemPlasticscintillatorLeadZIP detectorsPolyethyleneAncientLeadResults (2004)All events 968,680Not random trigger 940,619Analysis thresholds 79,460Singles 20,907Data quality 19,027Pile up 17,793Muon veto 17,339Ionization threshold 14,835Fiducial volume 7,615Nuclear-recoil band 23Phonon timing 1Only one event in one of the 6 detectors could be a WIMP signal.Unfortunately, this event is also consistent with expected misidentification due to electron recoils near the surface.Where do we stand
View Full Document
Unlocking...