Presentation on theme: "The DEAP Experiment Dark Matter Experiment with Argon PSD"— Presentation transcript:
1The DEAP Experiment Dark Matter Experiment with Argon PSD Kevin GrahamQueen’s UniversityM. Boulay, M. Chen, K. Graham, A. Hallin, J. Lidgard, R. Matthew,A.B. McDonald, K. Nicolics, P. SkensvedCase Western Reserve UniversityM. DragowskyLos Alamos National LaboratoryHime, D. Mei, K. Rielage, L. Stonehill, J. WoutersSNOLABF. Duncan, I. LawsonYale UniversityD. McKinsey, J. Nikkel
2Evidence for Dark Matter lensing gmeasure lens mass frommultiply imaged arcsmeasure velocities of galaxies in clustermeasure velocity of gas/starsvs radius from galactic centrev2c = G M(r) / rif light traces mass v shouldfall at large radii…but does notHST Abell 221885% of matter is dark matter!MihosNGC 2403
3Direct Detection of Dark Matter Cold Dark Matter a WIMPS (can also be LSP!)predict at the earth:dark matter energy density 0.3 GeV/cm3Sun orbiting at 220 km/sfor a given mass and interaction cross-sectionestimate c-n scattering rate /kg/year/keVdirect measurement:look for: elastic scattering of WIMPsin detector producing nuclear recoilsa low energy and falling keVause LAr with PSDDM signal or improve limit on scatteringcross-section (expect 10’s of events/year)c40Ar
4Detection in LAr ionizing radiation forms dimers in LAr dimers produced in singlet(I1) or triplet(I3) statesinglet state decay time much shorter than tripletintensity of singlet and triplet states depends onionization density along track and hence particle typens
6DEAP0 at LANL (Boulay and Hime) SetupGoals~1 kg LAr viewed by single2” PMTCsI counter used for tagcalibration with tagged g’s, n’s22Na: back-to-back 511 keV g’sAmBe: n and 4.4 MeV gdemonstrate pulse shapediscriminationdetermine b/g suppression level(expect O(108) from MC simulation)measure I1/I3 for g’s and neutronsPMTLArCsI tagVacuum chamberwindowssourceDigitizedPulseTotal Charge
7Deap0 Calibration 22Na 511 keV g AmBe neutron a ~0.1 PE/keV PromptPE = integral in 250 nsTotalPE = integral to 10 msFPrompt=PromptPE/TotalPEexpect ~0.3 for b/g ~0.8 for ndetermine charge/single PEknow peak for 22Na is 511 keVa ~0.1 PE/keV(sets sensitivity)22Na 511 keV gAmBe neutron22Na 511 keV g
8Preliminary Results 22Na AmBe determine fraction of 22Na above 0.7 for PE suppression O(105)consistent withbackground limitsneutrons in regionabove 0.7uncorrected b/g and neutron I1/I322NaAmBeuse background data to determine real and accidental coincidence rate
9DEAP1 ~10 kg of liquid argon view with 2 - 5” PMT’s use clean materials and shielding in constructioncalibrate detector response at Queen’smove to SNOLAB early in 2007measure b/g suppression down to 10 keV thresholdposition reconstruction in “z”at SNOLAB understand background rates/typescan already be competitive within a fewmonths exposure!prepare for 1 tonne experiment
10Neck connects to vacuum and Gas/liquid linesQuartz windows11” x 6” Stainless steel tee6” acrylic guideAcrylic vacuum chamberPMT 5”inner surface 97% diffuse reflector,covered with TPB wavelength shifter
11DEAP1 Constructed! first LAr fill 2 weeks ago response looks good! begin calibrating next week
13DM Sensitivity with LAr with 1-year exposure LAr with 10 keV (electron) thresholdDEAP1
14Summary initial proof-of-principle PSD (complete) calibration of DEAP1 at Queen’s (first fill so far)aPE/keV, reconstruction, b/n response at 10 keVcalibrate and understand backgrounds at depthif bkg controlled competitive DM limits soon!begin design of DEAP3(1 tonne) experiment!
15LAr Cryostat wall Decay in bulk detector tagged by a-particle energy 210Po onsurfaceDecay in bulkdetector taggedby a-particleenergyDecay fromsurface releasesuntaggedrecoiling nucleusCryostatwallLAraFig 6: Alpha emitters deposited on the detectorsurface are a potentially dangerous background.
18Dewar Schematic liquefy purified Argon gas and maintain at 85o K vacuum chamberargon lineliquid nitrogen at ~30 PSIgetter
19CDMS (Cryogenic Dark Matter Search) g raysExploits difference indeposited charge versusphonon energy betweenb/g ‘s and nuclear recoilsCollection of small detectorssimultaneously measure deposited energy in charge and phonon channels~1 kg / “tower”Current best limitneutrons(Currently instrumented5 kg mass)ZIP detector g GeImage from cdms.berkeley.edu
21Direct detection prediction from SUSY NMSSM (Next-to-MSSM)Prediction from talk byDavid Cerdeno at SUSY 2005(JHEP 12 (2004) 048)10-44 cm2 (10 kg LAr)10-45 cm2 (100 kg LAr)maybe within our reach!
22SNOLAB Excavation Status DEAP Collab Mtg 10 May 2006
23Evidence for Dark Matter clustering of galaxies (LSS)sensitive to amount of DMangular power spectrum of CMBsensitive to baryonic, DM, DEVirgo ConsortiumAdd breakdown of matter content here
24For almost as long as WIMPs have been around (if they DO exist!)…U, Th chains are present inall materials with 109, 1010 y lifetimes~104decays/kg/year for ppt (1 in 10-12)impuritiesRemoving backgrounds to WIMP particleinteractions is the task of DM searchers
25CDMS (Cryogenic Dark Matter Search) g raysExploits difference indeposited charge versusphonon energy betweenb/g ‘s and nuclear recoilsCollection of small detectorssimultaneously measure deposited energy in charge and phonon channels~1 kg / “tower”Current best limitneutrons(Currently instrumented5 kg mass)ZIP detector g GeImage from cdms.berkeley.edu
26XENON (proposed experiment) Total Xe mass 1 tonneExploits difference inionization signal (electrons)versus scintillation signal(photons) between b/g‘s andnuclear recoilsFigure from Elena Aprile Dark Matter 2004
27Background rejection with LAr (simulation) From simulation,rejection > 108@ 10 keV(>>!)108 simulated e-’s100 simulatedWIMPs
29Photomultiplier tube (PMT) backgrounds in DEAP-1 For reference, 250 events/year for the ET9390 PMTs
30Optimizing optics for DEAP-1 elg = 0.8epmt = 0.25a = 0Y0 = 40 photons/keVModel incorporatingreflective losses andabsorption:Y=R[1/S-1] elgepmt(1-a)Y0Y = yield [photons/keV]R = surface reflectivityS = surface PMT coverageelg = light guiding efficiencyepmt = PMT efficiencya = absorptionY0 = photon production yieldNeed real model to map inputs to yield,O(10%) (Kati N.)
31Dark Matter Candidates Baryonic Dark Matter - MACHOs- Brown DwarfsHot Dark Matter - neutrinosNon-Standard Gravity - MONDCold Dark Matter - Axions- WIMPs- R-parity conserving supersymmetric modelspredict stable LSP (typically neutralino c)- can have ‘right’ properties for cold dark matter!
32Evidence for Dark Matter angular power spectrum of CMBsensitive to baryons, DM, DE85% of matter is dark matter!neutrinos ~few % of matterWMAP Three Year Results
33Summary using SNOLAB facility and based on the experience and success of SNO, there is a unique opportunityfor Canadians to lead experimental research in- direct search for dark matter- low-energy solar neutrinos- neutrinoless double beta decaySNO+ will have access to most interesting physicsfor low-energy solar neutrinos and experiment is built!DEAP can rapidly evolve from concept to leading edgedark matter experiment – simple, inexpensive, scalable!
34Backgrounds expect DM small signal /keV/tonne/day background suppression crucialnon-nuclear recoil events PSDnuclear recoil events (shielding, reconstruction)clean clean clean clean clean!