TeVPA Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba e - (+ 2ν e )

TeVPA Why use xenon? Xenon isotopic enrichment is easier. 200kg of Xe has already been enriched to 80% in 136 Xe Xenon is “reusable”. Can be repurified & recycled into new detector Monolithic detector. LXe is self shielding, surface contamination minimized. Minimal cosmogenic activation. No long lived radioactive isotopes of Xe. … admits a novel coincidence technique. Background reduction by Ba daughter tagging. Energy resolution is poorer than the crystalline devices (~factor 10), but

TeVPA Ba Ion Identification Ba + system well studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980) Ba + system well studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980) Very specific signature: “shelving” Very specific signature: “shelving” Single ions can be detected from a photon rate of 10 7 /s Single ions can be detected from a photon rate of 10 7 /s Important additional Important additional constraint constraint Drastic background Drastic background reduction reduction 6P 1/2 5D 3/2 6S 1/2 493nm 650nm Metastable 47s  R = 5.28 MHz  B = 15.2 MHz

TeVPA Paths to a Ton Scale Experiment EXO-200 –Low-background Xe TPC with 200kg of 80% enriched 136 Xe –No Ba Tagging Liquid Phase Barium Tagging –Ion transfer from LXe to ion trap –Ba tagging in Situ –Ba tagging in SXe Gas Phase R&D –~100kg prototype detectors –Ion manipulation in gas

TeVPA EXO-200

TeVPA Improving the Energy Resolution ~570 keV Ionization and Scintillation results using 207 Bi Ionization alone: σ(E)/E = 570 keV or Q ββ or Q ββ Ionization & Scintillation: σ(E)/E = 570 keV or Q ββ or Q ββ E.Conti et al. Phys. Rev. B (68) EXO-200 will collect 3-4 times as much scintillation…

TeVPA teflon light reflectors flex cables on back of APD plane (copper on kapton) field shaping rings (copper) acrylic supports LAAPD plane (copper) and x-y wires (photo-etched phosphor bronze) Central HV plane (photo-etched phosphor bronze) ~40 cm x-y crossed wires, 60 o

TeVPA EXO-200 Copper Chamber

TeVPA The EXO-200 detector class 100 clean room The Xe vessel HFE (Heat transfer fluid) Vacuum insulation 25cm enclosure of low activity lead Refrigeration feedthroughs HFE feedthrough Vacuum pump-out port

TeVPA Materials qualification database ~ 330 entries Neutron Activation Analysis (NAA) - Alabama (MIT reactor) ICP-MS and GD-MS - INMS (Ottawa), commercial outfits Radon emanation - Laurentian (Sudbury) Gamma counting - Neuchâtel, Alabama Alpha counting - Alabama, Carleton, SLAC, Stanford Monte Carlo

Xenon Handling System xenon condenser xenon purity monitor and heater EXO-200 goal: 0.1 ppb O 2 equivalent t ~ 4 ms (electrons)

TeVPA muon flux at WIPP (~ 1700 m.w.e.): 4.77×10 -3 m -2 s -1 (3.10×10 -3 m -2 s -1 sr -1, ~15 m -2 h -1 ) E.-I.Esch et al., Nucl. Instr. Meth. A 538(2005)516 ★ EXO-200

TeVPA Assumptions: 1)200kg of Xe enriched to 80% in 136 2)σ(E)/E = 1.4% obtained in EXO R&D, Conti et al., Phys Rev B 68 (2003) )Low but finite radioactive background: 20 events/year in the ±2σ interval centered around the (0.4) keV endpoint 1 5)Negligible background from 2  (T 1/2 >1·10 22 yr) 2 EXO-200 Majorana mass sensitivity EXO-200 Case Majorana mass (meV) QRPA 3 NSM 4 40 Radioactive Background (events) 6.4* * T 1/2 0ν (yr, 90%CL) σ E 2.5MeV (%) Run Time (yr) Eff. (%) Mass (ton) 1) M. Redshaw, J., McDaniel, E. Wingfield and E.G. Myers (Florida State Precision Penning Trap), to be submitted to Phys. Rev C. 2) R. Bernabei et al., Phys. Lett. B 546, 23 (2002) 3) Rodin, et. al., Nucl. Phys. A 793 (2007) ) Caurier, Phys. Rev. Lett. 100, (2008)

TeVPA Future Plans All EXO-200 infrastructure is underground undergoing final testing The LXe TPC is built Electronics testing underway The TPC is scheduled to be installed in the cryostat before the end of 2009 Running will start next year with natural Xenon with an eventual switch to enriched Xenon Ba Tagging and gas phase R&D ongoing

TeVPA Stanford University, Stanford, Ca Enriched Xenon Observatory for double beta decay K.Barry, E.Niner, A.Piepke Physics Dept, U. of Alabama, Tuscaloosa Al P.Vogel Physics Dept Caltech, Pasadena Ca M.Dixit, K.Graham, C.Green, C.Hagemann, C.Hargrove, E.Rollin, D.Sinclair, V.Strickland Carleton University, Ottawa, Canada C. Benitez-Medina, S.Cook, W.Fairbank Jr., K.Hall, B.Mong Colorado State U., Fort Collins Co M.Moe Physics Dept UC Irvine, Irvine Ca D.Akimov, I.Alexandrov, A.Burenkov, M.Danilov, A.Dolgolenko, A,Karelin, A.Kovalenko, A.Kuchenkov, V.Stekhanov, O.Zeldovich ITEP Moscow, Russia B.Aharmim, K.Donato, J.Farine, D.Hallman, U.Wichoski Laurentian U., Sudbury, Canada H.Breuer, C.Hall, L.Kaufman, D.Leonard, S. Slutsky, Y-R. Yen U. of Maryland, College Park Md K.Kumar, A.Pocar U. of Massachusetts, Amherst Ma M.Auger, G.Giroux, R.Gornea, F.Juget, G.Lutter, J-L.Vuilleumier, J-M.Vuilleumier Laboratory for High Energy Physics, Bern, Switzerland N.Ackerman, M.Breidenbach, R.Conley, W.Craddock, S. Herrin, J.Hodgson, D.McKay, A.Odian, C.Prescott, P.Rowson, K.Skarpaas, K.Wamba, J.Wodin, L.Yang, S.Zalog SLAC, Menlo Park CA L.Bartoszek, R.DeVoe, M.Dolinski, P.Fierlinger, B.Flatt, G.Gratta, M.Green, F.LePort, M.Montero-Diez, R.Neilson, A.Reimer-Müller, A.Rivas, K.O’Sullivan, K.Twelker

TeVPA Back up Slides

TeVPA Xenon Enrichment Total of 200kg of Xe enriched to 80% in 136 Xe EXO Stockpile Natural Xe Enriched Xe

TeVPA Ba Tagging

TeVPA CCD e- Quadrupole linear ion trap Ba + grabber Ba + Tagging Schematic for EXO

TeVPA Single Ba ion trapping... Ba ovene-gun Fluorescence imaging 0 V -10 V RF quadrupole potential in each segment Multiply by 16, and add a buffer gas to cool down the ions injected at one end of the trap into a DC minimum short longitudinal trapping segment radial trapping longitudinal trapping

TeVPA Detection of Single Ions in Buffer Gas Single ion cloud (5 s integration) Torr He P(493) = 75 μW P(650) = 300 μW 1 ion 2 ions 3 ions 0 ions 1 ion 2 ions 3 ions M. Green, et al. Phys. Rev. A (2007) Electrodes glowing from scattered laser light

TeVPA Capacitive cryo-tip Picture of sensor 1 mm 2 mm Cryo-tip (ground) Electrostatic field lines Capacitive sensor (-HV) Ion mobility: µ ~ 0.3 cm 2 /kVs K. Wamba et al., NIM A 555 (2005) 205 v = µ x 1kV/cm ~ 0.3 cm/s from LXe

TeVPA Full EXO Sensitivity Assumptions: 1)80% enrichment in 136 2)Intrinsic low background + Ba tagging eliminate all radioactive background 3)Energy res only used to separate the 0ν from 2ν modes: Select 0ν events in a ±2σ interval centered around the (0.4) keV endpoint 1 4)Use for 2νββ T 1/2 >1·10 22 yr 2 1) M. Redshaw, J., McDaniel, E. Wingfield and E.G. Myers (Florida State Precision Penning Trap), to be submitted to Phys. Rev C. 2) R. Bernabei et al., Phys. Lett. B 546, 23 (2002) 3) Rodin, et. al., Nucl. Phys. A 793 (2007) ) Caurier, Phys. Rev. Lett. 100, (2008) Aggressive Conservative Case Majorana mass (meV) QRPA 3 NSM (use 1) 0.5 (use 1) 2νββ Background (events) 4.1* †1† * * 5701 T 1/2 0ν (yr, 90%CL) σ E 2.5MeV (%) Run Time (yr) Eff. (%) Mass (ton)