Future Noble Endeavors: Noble Liquid Detectors Searching ...lux.brown.edu/talks/100113_dm_noble_gaitskell_v36_08.pdf · Dark Matter Searches Rick Gaitskell, Brown University, LUX

Future Noble Endeavors:Noble Liquid Detectors Searching for Particle

Dark Matter

Rick Gaitskell, Joint Spokesperson, LUX CollaborationSpokesperson, LZ-DUSEL Collaboration

Particle Astrophysics Group, Brown University, Department of Physics(Supported by US DOE HEP)

see information athttp://luxdarkmatter.org

http://particleastro.brown.edu/

20 years in dark matter

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PHYSICS ITALIAN STYLE XENON10 @ Gran Sasso

CDMS II: Winter@Soudan Minnesota

New Sanford LabLUX @Homestake, South Dakota

Key points. I’m going to ...

• declare my ignorance

• demonstrate why particle astrophysicists can do their best work 1 mile underground

• explain why it is worth paying attention in this lecture

3

Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE

Medieval Universe

From Joel Primack, UC Santa Cruz4


Confession

>95% of the Composition of the Universe is still unknown

5

What is the Universe made of ?

Growth of Structure

7

CMB SnapshotUniverse became transparent at z~1000 , 380 kyrs

NOWz~0 , 14 GYr (Now)

ΔΤ/Τ~10-5 10 µΚ / 2.7Κ

ColdDarkMatter

Dark Matter, Sept 2007 Rick Gaitskell, Brown University, DOE

DM Direct Search Progress Over Time (2009)

~1 event kg-1 day-1

~1 event 1 tonne-1 yr-1

8

(Gross Masses kg)

ZEPLIN III.1

ZEPLIN III.2

LZ-S 1500kg

LZ 20t

CDMS Soudan 2008

LUX 350kg

XENON 100kgSuperCDMS

25 kgXMASS 800kgWARP 140kg

SuperCDMS 125 kgXENON 1000kg

σ=10-48

CDMS Soudan 2009


070807194801

http://dmtools.brown.edu/ Gaitskell,Mandic,Filippini

101

102

103

10-46

10-45

10-44

10-43

10-42

10-41

WIMP Mass [GeV]

Cro

ss-s

ecti

on

[cm

2]

(norm

alis

ed t

o n

ucl

eon)

Dark Matter Theory and Experiment

~1 event kg-1 day-1

~1 event tonne-1 month-1

• SOME SUSY MODELS [gray] Baer et al. (’03+upd ‘07) [red] T. Baltz and P. Gondolo,

Markov Chain Monte Carlos. JHEP 0410 (2004) 052, (hep-ph/0407039)

[blue] J. Ellis et al. CMSSM, Phys.Rev. D71 (2005) 095007, (hep-ph/0502001)

[red crosses] J. Ellis et al., LHC Benchmark Points

[green] Ruiz de Austri/Trotta/Roszkowski (2007) CMSSM Markov Chain Models (95% CL)

(lines)Current

Experimental Sensitivities

(dash)Goals in 2-5 years

(shaded)SUSY Theory

9(Spin Independent Coupling)

LHC ILC

WIMP Mass [GeV/c2]

Cro

ss-s

ecti

on

[cm

2]

(norm

alis

ed t

o n

ucl

eon

)

071011121600

http://dmtools.brown.edu/ Gaitskell,Mandic,Filippini

101

102

103

10-46

10-45

10-44

10-43

10-42

10-41

[Green] + [Red] inc :Ωh2~0.1 constraint)Well Tempered Neutralino(Hyperbolic Branch / Focus Point)Baer et al.JCAP 0701:017,2007hep-ph/0611387

Underground Laboratories Worldwide

SNOLab (6000 mwe)

Stanford (30 mwe)

CsI

Baksan

Gran SassoCanFranc

Modane/Frejus

Boulby

Soudan (2040 mwe) KamiokaKIMS

Mont Blanc

Homestake 4100 mwe(6500 mwe)

Oto Cosmo

WIPP (1900 mwe)


Radioactive Background Challenges• Search sensitivity (low energy region <<100 keV) Current Exp Limit < 1 evt/kg/month, ~< 10-1.5 evt/kg/day Goal < 1 evt/tonne/year, ~< 10-5 evt/kg/day

• Activity of typical Human?

11

12

How Many Gammas/Second?

>1,000 γ/ second/human


Background Challenges• Search sensitivity (low energy region <<100 keV) Current Exp Limit < 1 evt/kg/month, ~< 10-1.5 evt/kg/day Goal < 1 evt/tonne/year, ~< 10-5 evt/kg/day

• Activity of typical Human?• ~10 kBq (104 decays per second, 109 decays per day)

• Environmental Gamma Activity Unshielded 107 evt/kg/day (all values integrated 0–100 keV) This can be easily reduced to ~102 evt/kg/day using 25 cm of Pb

• Main technique to date focuses on nuclear vs electron recoil discrimination This is how CDMS II experiment went from 102 -> 10-1 evts/kg/day (continue push for >>99.99% rejection)

• Moving below this Reduction in External Gammas: e.g. High Purity Water Shield 4m gives <<1 evt/kg/day Gammas from Internal components - goal intrinsic U/Th contamination toward ppt (10-12 g/g) levels Detector Target can exploit self shielding for inner fiducial if intrinsic radiopurity is good

• Environmental Neutron Activity / Cosmic Rays => DEEP (α,n) from rock 0.1 cm-2 day-1

Since <8 MeV use standard moderators (e.g. polyethylene, or water, 0.1x flux per 10 cm Cosmic Ray Muons generate high energy neutrons 50 MeV - 3 GeV which are tough to moderate Need for depth (DUSEL) - surface muon 1/hand/sec, Homestake 4850 ft 1/hand/month

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Techniques for dark matter direct detection

TYPE DISCRIMINATIONTECHNIQUE

TYPICAL EXPERIMENT

ADVANTAGE

Ionization None(Ultra Low BG)

MAJORANA, GERDA Searches for ββ-decay, dm additional

Solid Scintillatorpulse shape

discrimination LIBRA/DAMA, KIMS low threshold, large

mass, but poor discrim

Cryogeniccharge/phononlight/phonon

CDMS, CRESSTEDELWEISS

demonstrated bkg discrim., low

threshold, but smaller mass/higher cost

Liquid noble gaslight pulse shape

discrimination, and/or charge/light

ArDM, Depleted Ar, LUX, WARP, XENON,

XMASS, ZEPLIN

large mass, good bkg discrimination

Bubble chamber super-heated bubbles/droplets

COUPP, PICASSO large mass, good bkg discrimination

Gas detectorionization track

resolvedDRIFT, NEWAGE, DMTPC, MIMAC

directional sensitivity, good discrimination

R.J. Gaitskell, Ann. Rev. Nucl. Par. Sci, 54 (2004) 315


Future of Direct Detection•Experiments under construction, to release results in 2009-2010 Target masses 10-300 kg Expect 10-100x better reach than existing limits.

•Next Round, for results in 2011-2013 Target masses 1-3 tonne, 103 x better reach Project cost $5-15M

•“Ultimate” Detectors, for results ~2014+ Target masses 3-50 tonne, 104 x better reach Project cost $20-50M

•Labs with 1-20 tonne dm experiments on roadmap Gran Sasso, Italy Frejus, France Canfranc, Spain Kamioka, Japan SNOLab, Canada Sanford Lab/DUSEL (Homestake), US

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W&C Dec. 17, 2009 1

CDMS Experiment

CDMSII at Soudan:

Five Towers (30 ZIPS)

operating since June ‘06

1 µ tungsten 380µ x 60µ aluminum fins

Z-sensitive Ionization and Phonon detectors

Soudan Mine

Most sensitive to spin-independent scattering: σ∝ A2

4.75 kg Ge(A=73), 1.1 kg Si(A=28)

W&C Dec. 17, 2009 2

Z-sensitive Ionization and Phonon

elec

tron

reco

ilsnuclear recoils

Ephonon

Ech

arg

e

4 phonon channels

(each is 1036 TES sensors in parallel)

inner sensor+

outer guard

(phonon side)

(charge side)

Signature of a Nuclear Recoil

reduced ionization signal relative to phonon signal

7.6 cm diameter 1.0 cm thick

z

r

W&C Dec. 17, 2009 7

Unblinding (Net 200 kg-days)

We unblinded the signal region November 5, 2009masked signal region

masked signal region (2σ NR band)

All WIMP search data

W&C Dec. 17, 2009 9

Unblind Events Passing Timing Cut

2 events in the NR band pass the timing cut!

All WIMP search data passing the timing cut

Event 1: Tower 1, ZIP 5 (T1Z5) Sat. Oct. 27, 20078:48pm CDT

Event 2: Tower 3, ZIP 4 (T3Z4) Sun. Aug. 5, 20072:41 pm CDT

2 events near NR band

W&C Dec. 17, 2009 12

Final Comments

The probability to observe 2 or more surface events based on the estimated background is

20%

After including the neutron background, the probability to observe 2 or more events is

23%

These values indicate that the results of this analysis cannot be interpreted as significant evidence for WIMP interactions, but we

cannot reject either event as signal.

After finalizing the systematic uncertainty on the surface event estimate, the final surface event background estimate is:0.8±0.1(stat)±0.2(sys) events

Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE2110/28/2008 Hanguo Wang, UCLA 17

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Scintillation Light Intrinsic Backgrounds WIMP (100 GeV) Sensitivity vs Ge >10 keVr

Ne (A=20)$60/kg

100% even-even nucleus

85 nm Requires wavelength Shifter

Low BP (20K) - all impurities frozen outNo radioactive isotopes

Scalar Coupling: Eth>50 keVr, 0.02x

Axial Coupling: 0 (no odd isotope)

Ar (A=40)$2/kg(isotope separation >$1000/kg)~100% even-even

125 nmRequires wavelength shifter

Nat Ar contains ~39Ar 1 Bq/kg == ~150 evts/keVee/kg/day at low energies. Requires isotope separation, low 39Ar source, or very good discrimination (~106 to match CDMS II)


Axial Coupling: 0 (no odd isotope)

Xe (A=131)$1000/kg

50% odd isotope

175 nmUV quartz PMT window

136Xe double beta decay is only long lived isotope - below pp solar neutrino signal. Relevant for DM search below ~10-47 cm2. 85Kr can be removed by charcoal or distillation separation.


Axial Coupling: ~5x (model dep)Xe is 50% odd n isotope 129Xe, 131Xe

Noble Liquid Comparison (DM Detectors)

22

Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE23

Noble Liquid Dual phase Time Projection Chamber• Can measure single electrons and photons.• Charge yield reduced for nuclear recoils.• Good 3D imaging

— Eliminating edges crucial.

• Recent Results Experiments: XENON10 (2006-2007, Gran Sasso Italy) ZEPLIN II ZEPLIN III WARP 2.5 kg

• Construction/Commissioning XENON100 (Gran Sasso) LUX 350 kg (Sanford Lab, SD) WARP 140 (Gran Sasso) XMASS-DM 10 kg (Kamioka) ARDM (Canfranc)

• Single Phase is a distinct technique XMASS 800 kg CLEAN/DEAP 350 kg


• The rate of ER events in FV is determined by small angle scattering Compton events, that interact once in the FV The rate of above events is suppressed by the tendency for

the γ’s to scatter a second time. Either on the way in, or way out.

The chance of no secondary scatter occurring is more heavily suppressed the more LXe there is• The important optimization is to maximize the amount of LXe that

lies along a line from the greatest sources of radioactivity (PMTs?) that pass through the FV.

• Example for 1.5 MeV γ from outside LXe volume Energy Spectrum for part of energy deposited in FV Energy spectrum for all energy in detector Additional application of multiple scatters cut has little

additional effect on low energy event rate

• Conclusion for Event Suppression xyz resolution of detector is important simply in defining FV.

Little additional reduction from locating vertices. (Full xyz hit pattern does assist in bg source identification)

Topology of Gamma Events That Deposit Small Energy in FV

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To look like DM <20 keV energy deposition required in FV

60 triangle in total about 10PMT/triangle×60

Total: 642 PMTs Photo coverage: 62.4%

XMASS Design of 800 kg Detector

Hexagonal PMT Hamamatsu R10789QE 28-‐39%

Energy Threshold is about 5keVee

pentakisdodecahedron

XMASS Experiment

10m

10mPassive shield forγ and neutron from Rock

70 PMTs (20 inch) for the Water Cerenkov LightActive shield formuon induced events

•Kamioka, Japan 2700 m.w.e.

•800 kg of LXe, 100 kg fiducial volume.

•The goal is to explore 10-45 cm2 WIMP-nucleon cross section for the spin-independent case.

XMASS Schedule• The construction of the detector will be !nished in March

2010.

• The detector will be commissioned in April and May and WIMP search Run will be started just after that.

LUX Collaboration, 2009 Gaitskell <>

Evolution

From XENON10/ZEPLIN to LUX Self shielding much improved Fiducial Region

• 5 kg -> 100 kg Overall Increase sensitivity by ~100x

XENON1022 kg / Fiducial 5.4 kg

LUX350 kg / Fiducial 100 kg

Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE2910/28/2008 Hanguo Wang, UCLA 54

Princeton-Fermilab pursuing new depleted 39Ar detector in US

Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE30

LUX Experiment / Rick Gaitskell / Brown University 31

The LUX CollaborationCollaboration meeting, Homestake, March 2009Xenon10, CDMS

SNO, Borexino, Xenon10, CDMS

Xenon10, CLEAN-DEAP

SNO, KamLAND

Xenon10

EXO

Zeplin II

Double Chooz, CDF

Zeplin II

Formed in 2007, fully funded DOE/NSF in 2008

Majorana, CLEAN-DEAP

Harvard (June 2009)Masahiro Morii

Bob Jacobsen Professor

South Dakota School of Mines and Technology (August 2009)Xinhua BaiMark Hanardt

Gaitskell - Brown University / LUX 32

LUX Detector - Overview

Titanium Vessels

Dodecagonal field cage+ PTFE reflector panels

PMT holding copper plates

Counterweight

Feed-throughs for cables / pipesLN bath column

Radiation shield

49 cm59 cm

Cathode grid

Anode grid

Gaitskell - Brown University / LUX

LUX WIMP Sensitivity

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In < 2 live days we will surpass sensitivity of all existing results for dark matter direct detection experiments

Focus on discovery ... if dark matter cross section is factor 10 below current best 90% CL search limits ...

LUX Experiment / Rick Gaitskell / Brown University

LUX 350 kg / 100 kg Fiducial 100 days / WIMP Discovery

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Simulated LUX data(100 kg fiducial, 100 days)

mX = 100 GeV/c2

σ = 5 10-45 cm2

Red - Example of WIMP Signal if cross-section is 1/10th of current best limits (90% CL)

Blue - All ER background events in fiducial region after 100 live-days


LUX Detector - Internals

122 2" PMT R8778 175 nm, QE > ~30%U/Th ~9/3 mBq/PMTAll tested in LUX 0.1 program

Dodecagonal field cage+ PTFE reflector panels

Copper PMT holding plate

HV Grids in place and tested

Assembly taking place at Texas A&M since early 2009

0 20 40 60 80 100 120

10

10

100

Recirculation Time [hours]

Elec

tron

Drif

t Len

gth

[m]

Purification vs. Time, Run009

2 error bars1 error bars

Gaitskell / LUX Collaboration

Xenon Purity

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• ~9 hr time constant for purification

• > 2 m electron drift length achieved(> 1000 us) with 60kg target

•Errors dominated by use of 5 cm test cell drift within large cryostat

0.2 tonnes circulation per day


Sanford Lab @ Homestake

Davis Cavern 4300 m.w.e 4 µ/m2/d

Surface Facility

Funded with 70 M$ private donation+ 39 M$ from state of SDDemonstrator for DUSEL, but already competitive!


LUX Surface Facility @ Sanford Lab• Fully Operational Since Nov 2009 - Detector Assembly Started (Layout Same as Davis Underground Lab)•

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LUX Experiment / Rick Gaitskell / Brown University

1964 / 2009 “They want to fill the cavern with what ?*?”

Davis Cavern

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1964


LUX 1.0 – Davis Laboratory (4850L)Construction/excavation design completed

New 300’ access/safety tunnel to be excavatedShared access with Majorana facility, also to be excavated

Two storey, dedicated LUX 55’ x 30’ x 32’ facility, CL 100kIncludes CL 1k clean room, control room, counting facility

1964

Beneficial occupancy: May 2010

Rendering by J. Thomson

Lab

Mine shaft

Majorana

LUX

Mechanical& Electrical Services

200 m

Dark Matter, Sept 2007 Rick Gaitskell, Brown University, DOE

DM Direct Search Progress Over Time (2009)

~1 event kg-1 day-1

~1 event 1 tonne-1 yr-1

41

(Gross Masses kg)

ZEPLIN III.1

ZEPLIN III.2

LZ-S 1500kg

LZ 20t

CDMS Soudan 2008

LUX 350kg

XENON 100kgSuperCDMS

25 kgXMASS 800kgWARP 140kg

SuperCDMS 125 kgXENON 1000kg

σ=10-48

CDMS Soudan 2009


The LUX ZEPLIN program• LZ: LUX + ZEPLIN III + new US and European groups• LZS (Sanford): 1.5 ton instrument for Sanford Lab, just proposed.• LZD (DUSEL): Scale based on technically feasibility, cost.

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20-tons

2 m0.85 m0.5 m

LZS [Sanford] 1.5 tons

LZD [DUSEL] 20 tonnes

4 x LUX scale

LUX@Sanford 300 kg


LUX-ZEPLIN Collaboration for LZ-Sanford and LZ-DUSEL•Brown University

•Richard Gaitskell•Caltech

•Bob McKeown•Case Western Reserve University

•Thomas Shutt, Dan Akerib,Mike Dragowksi•Harvard

•Masahiro Morii•Imperial College, London

•Tim Sumner, Henrique Araujo•ITEP, Moscow

•Dmitri Akimov•Lawrence Berkeley National Laboratory

•Bob Jacobsen, Henrik von der Lippe. Jim Siegrist•Lawrence Livermore National Laboratory

•Adam Bernstein•LIP, Coimbra

•Isabel Lopes•Moscow State Engineering Physics Institute

•Alex Bolozdynya•South Dakota School of Mines & Tech

•Xinhau Bai•STFC Rutherford Appleton Laboratory

•Pawel Majewski•STFC Daresbury Laboratory

•John Simpson•Texas A&M

•James White•UC Berkeley

•Bob Jacobsen•UC Davis

•Robert Svoboda, Mani Tripathi, Richard Lander•UC Santa Barbara

•Harry Nelson•University of Edinburgh

•Alex Murphy•University of Maryland

•Carter Hall •University of Rochester

•Frank Wolfs•University of South Dakota

•Dongming Mei

International collaboration, with expertise in dark matter search, noble gas techniques, water detectors, high energy physics and large scale deployments (under/above grounds).

Includes PIs/Senior Researchers fromEXO, XENON10, LUX, ZEPLIN II, III, CDMS I, II, SNO, SuperK, Kamland, Borexino, IMB.

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Projections based onKnown background levels Previously obtained e- attenuation

lengths and discrimination factors

Fiducial volumes selected to match < 1 NR event in full exposure

LZ Program - WIMP Sensitivity

LUX (constr: 2008-2009, ops: 2010-2011) 100 kg x 300 days

LZ3 (constr: 2010-2011, ops: 2012-2013) 1,500 kg x 500 days

LZ20 (constr: 2013-2015, ops: 2016-2019) 13,500 kg x 1,000 days

10 events sensitivity

1 event sensitivity


LZ Program – Xe 20 tonnes, Ultimate Search?Electron Recoil signal limited by p-p solar neutrinos

Subdominant with current background rejection

Nuclear Recoil background: coherent neutrino scattering 8B solar neutrinosAtmospheric neutrinosDiffuse cosmic supernova background

LZ20 reaches this fundamental limit for direct WIMP searches

Electron Recoils

LZ20 also sensitive to ββ0ν decay in natural xenon up to lifetimes of ~1.3 1026 years !

L. Strigariastro-ph/0903.3630

Nuclear Recoils


Conclusion - Noble Liquids for Dark Matter

•Noble Status Past 5 years we have seen rapid progress in demonstrated performance (NR-ER discrimination/energy

resolution/light yields) of Noble Liquid Detectors in low energy regime Competitive WIMP Search Results from WARP (Ar), ZEPLIN II+III (Xe), XENON10 (Xe)

•Single Phase (Liquid only) - Pulse Shape Discrimination (ER) Ar/Ne demonstrating >107:1 discrimination at >50 keVr, difficulties demonstrating perf. @ lower thresholds

DEAP / CLEAN• Push these tests to >108:1 using higher light yields/shielding in test facilities (required for 10-45 cm2 dm reach)• 39Ar (160 evts /keVee/kg/day) / Rn daughters on surfaces (major issue)

Xe Self-shielding (XMASS) - Constructing 800 kg target Position reconstruction based on photoelectron hit patterns (timing not useful in <=10 tonne scale). Mis-

reconstruction is a concern - requires very good PMT coverage

•Dual Phase (Liquid Target/Ioniz Readout in Gas) - Discrim. Ionization/Photons+PSD (Ar) Xe TPC Operation: XENON100 / LUX350

• Discrimination established ~103:1 (50% NR acceptance), fiducialize to get further bg reduction — Xe intrinsically very low activity (cf XMASS) , so scaling works

Ar TPC (WARP) - studying use of Ionization + PSD ; Darkside (US) 2011+• Discrimination Ionization ~102:1 + PSD >104:1 (energy threshold should be improved with better elec.)

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Conclusions /2•Scaling of Technology Detector WIMP sensitivity improves very significantly with size

• Self shielding can be exploited if use single target volume• A number of experiments will deliver x10-100 improvement in sensitivity over existing measurements (in 2010)

Noble Liquid Designs are very scalable• Better than 1 evt/100 kg/month (<10-45 cm2) in 2010• These new experiments will demonstrate if >>1 tonne are reasonable, no obvious “show stoppers” so far

Cryogenic Detectors will continue to compete• But it requires long exposure periods to stay competitive with Noble targets• Major challenge will be cost / feasibility of >>100 kg targets

•Future Direct Detection Experiments 2011-> / In US DUSEL 2013+ Future instruments (multi-tonne) for 10-46 – 10-47 cm2 also realistic

• “Attempt to guarantee WIMP discovery if SUSY models are reasonable”• Need multiple targets / technologies to confirm observation & study signals

Solar Neutrinos will become background (require ER/NR discrimination to beat it down) Expect to form smaller number of large international collaborations

•Many Other Possibilities for Detection of Dark Matter Cosmic Rays / Neutrinos / LHC

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Documents

Future Noble Endeavors: Noble Liquid Detectors Searching ...lux.brown.edu/talks/100113_dm_noble_gaitskell_v36_08.pdf · Dark Matter Searches Rick Gaitskell, Brown University, LUX