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Current Status of The EXO-200 Experiment

Current Status of The EXO-200 Experiment. 136 Xe 136 Ba ++ + 2e - (+ 2ν e ). Kevin O’Sullivan Stanford University. Why use xenon?. Energy resolution is poorer than the crystalline devices (~factor 10), but.

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Current Status of The EXO-200 Experiment

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  1. Current Status of The EXO-200 Experiment 136Xe 136Ba++ + 2e- (+ 2νe) Kevin O’Sullivan Stanford University TeVPA 2009

  2. Why use xenon? Energy resolution is poorer than the crystalline devices (~factor 10), but Xenon isotopic enrichment is easier. 200kg of Xe has already been enriched to 80% in 136Xe 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. TeVPA 2009

  3. Ba Ion Identification • Ba+ system well studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980) • Very specific signature: “shelving” • Single ions can be detected from a photon rate of 107/s 6P1/2 650nm 493nm Metastable 47s 5D3/2 • Important additional • constraint • Drastic background • reduction GR = 5.28 MHz GB = 15.2 MHz 6S1/2 TeVPA 2009

  4. Paths to a Ton Scale Experiment • EXO-200 • Low-background Xe TPC with 200kg of 80% enriched 136Xe • 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 2009

  5. EXO-200 TeVPA 2009

  6. ~570 keV Improving the Energy Resolution Ionization and Scintillation results using 207Bi Ionization alone: σ(E)/E = 3.8% @ 570 keV or 1.8% @ Qββ Ionization & Scintillation: σ(E)/E = 3.0% @ 570 keV or 1.4% @ Qββ E.Conti et al. Phys. Rev. B (68) 054201 EXO-200 will collect 3-4 times as much scintillation… TeVPA 2009

  7. acrylic supports ~40 cm LAAPD plane (copper) and x-y wires (photo-etched phosphor bronze) Central HV plane (photo-etched phosphor bronze) teflon light reflectors field shaping rings (copper) flex cables on back of APD plane (copper on kapton) x-y crossed wires, 60o TeVPA 2009

  8. EXO-200 Copper Chamber TeVPA 2009

  9. Refrigeration feedthroughs The Xe vessel Vacuum insulation HFE feedthrough HFE (Heat transfer fluid) 25cm enclosure of low activity lead Vacuum pump-out port The EXO-200 detector class 100 clean room TeVPA 2009

  10. Materials qualification database • 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 ~ 330 entries TeVPA 2009

  11. Xenon Handling System xenon condenser xenon purity monitor and heater EXO-200 goal: 0.1 ppb O2 equivalent t ~ 4 ms (electrons)

  12. muon flux at WIPP (~ 1700 m.w.e.): 4.77×10-3 m-2 s-1 (3.10×10-3 m-2 s-1sr-1, ~15 m-2 h-1) E.-I.Esch et al., Nucl. Instr. Meth. A 538(2005)516 EXO-200 ★ TeVPA 2009

  13. Case Mass (ton) Eff. (%) Run Time (yr) σE/E @ 2.5MeV (%) Radioactive Background (events) T1/20ν (yr, 90%CL) Majorana mass (meV) QRPA3 NSM4 EXO-200 0.2 70 2 1.6* 40 6.4*1025 133 186 EXO-200 Majorana mass sensitivity Assumptions: 200kg of Xe enriched to 80% in 136 σ(E)/E = 1.4% obtained in EXO R&D, Conti et al., Phys Rev B 68 (2003) 054201 Low but finite radioactive background: 20 events/year in the ±2σ interval centered around the 2457.9(0.4) keV endpoint 1 5) Negligible background from 2nbb (T1/2>1·1022yr) 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) 213-215 4) Caurier, Phys. Rev. Lett. 100, 052503 (2008) TeVPA 2009

  14. 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 2009

  15. Enriched Xenon Observatoryfor 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 2009 Stanford University, Stanford, Ca

  16. Back up Slides TeVPA 2009

  17. Xenon Enrichment Natural Xe Total of 200kg of Xe enriched to 80% in 136Xe Enriched Xe EXO Stockpile TeVPA 2009

  18. Ba Tagging TeVPA 2009

  19. e- e- e- e- e- e- Ba+ Tagging Schematic for EXO Ba+ grabber Quadrupole linear ion trap CCD TeVPA 2009

  20. 0 V -10 V Single Ba ion trapping 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 Ba oven e-gun Fluorescence imaging ... longitudinal trapping short longitudinal trapping segment radial trapping TeVPA 2009

  21. Detection of Single Ions in Buffer Gas 3 ions 2 ions 1 ion Single ion cloud (5 s integration) 0 ions 2 ions 1 ion 0 ions 10-3 Torr He P(493) = 75 μW P(650) = 300 μW 3 ions Electrodes glowing from scattered laser light TeVPA 2009 M. Green, et al. Phys. Rev. A 76 023404 (2007)

  22. Capacitive cryo-tip 2 mm Cryo-tip(ground) 1 mm Picture of sensor Electrostatic field lines Capacitive sensor (-HV) from LXe Ion mobility: µ ~ 0.3 cm2/kVs v = µ x 1kV/cm ~ 0.3 cm/s K. Wamba et al., NIM A 555 (2005) 205 TeVPA 2009

  23. Case Mass (ton) Eff. (%) Run Time (yr) σE/E @ 2.5MeV (%) 2νββ Background (events) T1/20ν (yr, 90%CL) Majorana mass (meV) QRPA3 NSM4 Conservative 1 70 5 1.6* 0.5 (use 1) 2*1027 24 33 Aggressive 10 70 10 1† 0.7 (use 1) 4.1*1028 5.3 7.3 Full EXO Sensitivity • Assumptions: • 80% enrichment in 136 • Intrinsic low background + Ba tagging eliminate all radioactive background • Energy res only used to separate the 0ν from 2ν modes: • Select 0ν events in a ±2σ interval centered around the 2457.9(0.4) keV endpoint1 • 4) Use for 2νββ T1/2>1·1022yr2 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) 213-215 4) Caurier, Phys. Rev. Lett. 100, 052503 (2008) TeVPA 2009

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