Comparing Large Comparing Large Underground Underground

Neutrino Neutrino Detector Detector

Technologies:Technologies:Liquid Argon, Liquid Argon,

Liquid Scintillator, Liquid Scintillator, and Water and Water CherenkovCherenkovJohn G. Learned

University of Hawaii

at ANT09, Hawaii A personal view, based upon experience with all three technologies.A personal view, based upon experience with all three technologies.

Good source papers: “Report on the Depth Requirements for a Massive Detector atHomestake”, arXiv:0907.4183v2; Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects”, arXiv:0705.0116v2

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The three detectors in the LAGUNA The three detectors in the LAGUNA studystudy

1 vertical

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Material PropertiesMaterial Properties

PropertyProperty ScintScint WaterWater ArgonArgon

Z 1,12 (1:1) 1,16(2:1) 40

X0 /cm 42 36 20

p /gm/cm3 0.8 – 1.0 1.0 1.39

Λint /gm/cm2 75.7 84.6 117.2

Λcol /gm/cm2 55.7 60.1 76.4

-dE/dx /gm/cm2 2.30 1.99 1.52

n (optical) 1.49 1.33 1.23

θms/√X0 2.1 2.3 3.1

~Cost /$/kg 3 0.2 2

All three media are readily available in industrial quantities.

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Water CherenkovWater Cherenkov• Cheapest target medium (but

not negligible with filtering and dopants)

• Only route to megaton instruments

• Well proven technology (IMB, Kam, SK)

• Excellent for mu/e separation ~1 GeV.

• Electron scattering for solar nus.

• Threshold above ~4 MeV => no geonus or n-p captures. n detection needs Gd.

• No complex event topologies.

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Liquid Scintillation Liquid Scintillation DetectorsDetectors

• Hi resolution, low threshold (<MeV)

• Technology well developed (50 years, plus Borexino, KamLAND and soon SNO+)

• Excellent for anti-neutrino detection by inverse beta decay.

• Liquid too expensive beyond ~100kT.

• New recognition: GeV neutrino physics too.

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Liquid Argon TPC Liquid Argon TPC DetectorsDetectors

• Bubble chamber-like imaging, detailed event topology, with few mm resolution.

• Developed over 30 years, and now being applied in 600 ton Icarus in Gran Sasso.

• No free protons for nucleon decay or inverse beta studies.

• Only detector for potential discrimination of e+ from e-

at neutrino factory.

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Energy Range of InterestEnergy Range of Interest

Large Underground

Detectors

Accelerator Neutrinos

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Liquid TreatmentLiquid Treatment

• All three require special facilities, all expensive and a bit hard to compare.

• Lesson of past: do great job on do great job on first fill into superclean detectorfirst fill into superclean detector, have radon tight system, and do not have to recirculate much or at all.

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Muon Rates for 100 kiloton Detectors at Homestake

Depth/ft Depth/mwe Muon Rate/2150m^2/

sec

300 265 1616

1000 880 215

2600 2300 2.8

3350 2960 0.71

3950 3490 0.32

4100 3620 0.14

4850 4290 0.05

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Depth RequirementsDepth Requirements

• All depends upon physicsphysics goals…• Also depends upon detector size…

external backgrounds (eg. from muon showers in rock); worst for small instruments. Big detectors take hit near periphery.

• Great depth only needed for MeV measurements (geonus, low end of solar).

• PDK, accelerator studies, atm nus, SN, DSNB all can be done at much less depth… exact depth arguable depending upon technique and physics.

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Rough Graphical Representation of Depth Rough Graphical Representation of Depth RequirementsRequirements

Depth/kmwe

0H2O LS LAr

1

2

3

4

5

Long Baseline ~1GeV ν’s

Nucleon Decay

SupernovaSupernova ~No ~No BackgroundBackground

ReactorsReactors

Diffuse SN NeutrinosDiffuse SN Neutrinos

Geo-NeutrinosGeo-Neutrinos

Many caveats required, but trend is correct... jgl opinion

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Nucleon Decay PredictionsNucleon Decay Predictions

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Nucleon DecayNucleon Decay

43/2.2543/2.251.0 x 1035

The e+π0 estimate for LENA is based upon new fitting methods.

L Ar LS H2O

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Supernova RatesSupernova Rates

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Diffuse Supernova Neutrino Diffuse Supernova Neutrino BackgroundBackground

Better low energy atmospheric neutrino flux calculations needed.

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Physics Summary Comparison ChartPhysics Summary Comparison ChartPhysics Scint Water Argon

PDK e+pi0 1.0E35 yr 1.0E35 yr 0.4E35 yr

PDK nu-K 0.4E35 yr 0.2E35 0.6E35

Free p’s Yes Yes No

Relic Sn nusRelic Sn nus <1/cm2<1/cm2 ~1/cm2~1/cm2 NoNo

Solar nus Yes Yes Yes

PeP Yes Yes Yes

Geo nusGeo nus YesYes NoNo NoNo

SN burstSN burst 2E42E4 2E52E5 6e46e4

EEthreshthresh <1 MeV<1 MeV ~4 MeV~4 MeV ~1 MeV~1 MeV

Nucl ThreshNucl Thresh 15 MeV15 MeV 30 MeV30 MeV 60 MeV60 MeV

Reactor NusReactor Nus YesYes Iff GdIff Gd NoNo

Reactor Reactor HierarchyHierarchy

YesYes NoNo NoNo

Reactor Reactor Theta13Theta13

YesYes NoNo NoNo

Atm nusAtm nus YesYes YesYes YesYes

LBL e appearLBL e appear YesYes YesYes YesYes

LBL e+/e-LBL e+/e- NoNo NoNo YesYes

Indir WIMPs Yes Yes Yes

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LAGUNA Seems to be on the LAGUNA Seems to be on the map!map!

Who will win?

Plus Japan (HyperK). Plus Japan (HyperK).

How will DUSEL fit into this picture?How will DUSEL fit into this picture?

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Bottom LineBottom Line

• Each has strengths• Long range: LAr wins for detailed neutrino

physics in LBL, tho nice anytime• Great sizes (megaton): H2O wins• Low energies: Liquid Scint wins

(particularly for geonus)• Cost/vol hierarchy: LAr:LS:H2O• Readiness: LS & H2O > LAr

• I like them all!!I like them all!!