TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe...

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TeVPA 2009 1 Current Status of The EXO- 200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )
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Page 1: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 1

Current Status of The EXO-200 Experiment

Kevin O’SullivanStanford University

136Xe 136Ba++ + 2e- (+ 2νe)

Page 2: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

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

Page 3: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 3

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

Page 4: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

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

Page 5: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 5

EXO-200

Page 6: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 6

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…

Page 7: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 7

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

Page 8: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 8

EXO-200 Copper Chamber

Page 9: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 9

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

Page 10: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 10

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

Page 11: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

Xenon Handling Systemxenon condenser

xenon purity monitor and heater

EXO-200 goal: 0.1 ppb O2 equivalentt ~ 4 ms (electrons)

Page 12: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 12

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

Page 13: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 13

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) 054201

3) 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)

Page 14: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

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

Page 15: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

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

Page 16: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 16

Back up Slides

Page 17: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 17

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

Page 18: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 18

Ba Tagging

Page 19: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 19

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

Page 20: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 20

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

Page 21: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 21

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

Page 22: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 22

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

Page 23: TeVPA 20091 Current Status of The EXO-200 Experiment Kevin O’Sullivan Stanford University 136 Xe 136 Ba ++ + 2e - (+ 2ν e )

TeVPA 2009 23

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)

2νββ

Background

(events)

4.1*10281†107010

2*10271.6*5701

T1/20ν

(yr, 90%CL)

σE/E @

2.5MeV

(%)

Run Time

(yr)

Eff.

(%)

Mass

(ton)