Download - Current Status of The EXO-200 Experiment
TeVPA 2009 1
Current Status of The EXO-200 Experiment
Kevin O’SullivanStanford University
136Xe 136Ba++ + 2e- (+ 2νe)
TeVPA 2009 2
Why use xenon?
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.
Energy resolution is poorer than the crystalline devices (~factor 10), but
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Ba Ion IdentificationBa Ion Identification
• BaBa++ system well studied system well studied (Neuhauser, Hohenstatt, Toshek, (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980)Dehmelt 1980)• Very specific signature: Very specific signature: “shelving”“shelving”• Single ions can be detected Single ions can be detected from a photon rate of 10from a photon rate of 1077/s/s
• Important additionalImportant additional constraintconstraint• Drastic backgroundDrastic background reductionreduction
6P6P1/21/2
5D5D3/23/2
6S6S1/21/2
493nm
650nm
Metastable 47sMetastable 47s
R = 5.28 MHzB = 15.2 MHz
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
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EXO-200
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Improving the Energy Resolution
~570 keV~570 keV
Ionization and Scintillation results using 207Bi Ionization alone:Ionization alone:
σσ(E)/E = 3.8% @ 570 keV(E)/E = 3.8% @ 570 keV or 1.8% @ Qor 1.8% @ Qββββ
Ionization & Scintillation:Ionization & Scintillation:σσ(E)/E = 3.0% @ 570 keV(E)/E = 3.0% @ 570 keV
or 1.4% @ Qor 1.4% @ Qββββ
E.Conti et al. Phys. Rev. B (68) E.Conti et al. Phys. Rev. B (68) 054201054201
EXO-200 will collect 3-4 EXO-200 will collect 3-4 timestimes
as much scintillation…as much scintillation…
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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, 60o
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EXO-200 Copper Chamber
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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
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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 Systemxenon condenser
xenon purity monitor and heater
EXO-200 goal: 0.1 ppb O2 equivalentt ~ 4 ms (electrons)
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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
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Assumptions: 1) 200kg of Xe enriched to 80% in 1362) σ(E)/E = 1.4% obtained in EXO R&D, Conti et al., Phys Rev B 68 (2003) 0542013) 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 2 (T1/2>1·1022yr) 2
EXO-200 Majorana mass sensitivityEXO-200 Majorana mass sensitivity
EXO-200
Case
186133
Majorana mass(meV)
QRPA3 NSM440
Radioactive
Background
(events)6.4*10251.6*2700.2
T1/20ν
(yr, 90%CL)
σE/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) 213-2154) Caurier, Phys. Rev. Lett. 100, 052503 (2008)
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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 15Stanford University, Stanford, Ca
Enriched Xenon Observatoryfor double beta decay
K.Barry, E.Niner, A.PiepkePhysics Dept, U. of Alabama, Tuscaloosa Al
P.VogelPhysics Dept Caltech, Pasadena Ca
M.Dixit, K.Graham, C.Green, C.Hagemann, C.Hargrove, E.Rollin, D.Sinclair, V.StricklandCarleton University, Ottawa, Canada
C. Benitez-Medina, S.Cook, W.Fairbank Jr., K.Hall, B.MongColorado State U., Fort Collins Co
M.Moe PhysicsDept 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, RussiaB.Aharmim, K.Donato, J.Farine, D.Hallman, U.Wichoski
Laurentian U., Sudbury, CanadaH.Breuer, C.Hall, L.Kaufman, D.Leonard, S. Slutsky, Y-R. Yen
U. of Maryland, College Park MdK.Kumar, A.Pocar
U. of Massachusetts, Amherst MaM.Auger, G.Giroux, R.Gornea, F.Juget, G.Lutter, J-L.Vuilleumier, J-M.Vuilleumier
Laboratory for High Energy Physics, Bern, SwitzerlandN.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.ZalogSLAC, 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
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Back up Slides
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Xenon EnrichmentXenon Enrichment
Total of 200kg of Xe enriched Total of 200kg of Xe enriched to 80% in to 80% in 136136XeXe
EXO Stockpile
Natural Xe
Enriched Xe
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Ba Tagging
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CCDCCD
e-
e-e-
e- e-
e-
Quadrupole linear Quadrupole linear ion trapion trap
BaBa++ grabbergrabber
BaBa++ Tagging Schematic for EXO Tagging Schematic for EXO
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Single Ba ion trapping
...
Ba oven e-gun Fluorescence imaging
0 V
-10 V
RF quadrupole potential in each segmentMultiply 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
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Detection of Single Ions in Buffer Gas
Single ion cloud(5 s integration)
10-3 Torr HeP(493) = 75 μWP(650) = 300 μW
1 1 ionion
2 2 ionsions
3 3 ionsions
0 ions0 ions
0 0 ionsions
1 1 ionion
2 2 ionsions
3 3 ionsions
M. Green, et al. Phys. Rev. A 76 023404 (2007)
Electrodes glowing from scattered laser light
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Capacitive cryo-tip
Picture of sensor1 mm
2 mmCryo-tip (ground)
Electrostatic field lines Capacitive
sensor (-HV)
Ion mobility: µ ~ 0.3 cm2/kVs
K. Wamba et al., NIM A 555 (2005) 205
v = µ x 1kV/cm ~ 0.3 cm/s
from LXe
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Full EXO SensitivityAssumptions: 1) 80% enrichment in 1362) Intrinsic low background + Ba tagging eliminate all radioactive background3) 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) 213-2154) Caurier, Phys. Rev. Lett. 100, 052503 (2008)
Aggressive
Conservative
Case
7.3
33
5.3
24
Majorana mass(meV)
QRPA3 NSM4
0.7 (use 1)
0.5 (use 1)
2νββBackgroun
d(events)
4.1*10281†107010
2*10271.6*5701
T1/20ν
(yr, 90%CL)
σE/E @ 2.5MeV
(%)
Run Time(yr)
Eff.(%)
Mass(ton)