Caren Hagner 15.5.2012 LENA: Low Energy Neutrino Astronomy The LAGUNA Liquid Scintillator Detector...

Caren Hagner – 15.5.2012

LENA: LLENA: Low ow EEnergy nergy NNeutrino eutrino AAstronomystronomy

The LAGUNA Liquid Scintillator Detector

Caren Hagner (Hamburg University) for the LAGUNA-LENA working group

See also Posters: LENA as Far Detector for Beam Neutrinos

(Kai Loo) LENA Low Energy neutrino physics

(Michael Wurm) Neutrino Oscillometry with LENA

(Yuri Novikov and W. Trzaska) LENA Detector Design

(Daniel Bick)


Physics Options at Low EnergiesPhysics Options at Low Energies

Neutrino Sources Galactic Supernova neutrinos 104/SN Diffuse Supernova neutrinos 10/yr Solar neutrinos 104/d Geoneutrinos 103/yr Reactor neutrinos 103-4/yr Neutrino oscillometry 104/Mci Pion decay-at-rest beam Indirect dark matter search

Substantial progress with event reconstruction at few 100MeV – few GeV: Long Baseline Neutrino Observation possible

→ mass hierarchie

Low energy threshold, Radiopurity


LENA Whitepaper just publishedLENA Whitepaper just published

Astroparticle Physics 35 (2012) 685-732


LENA Detector Design (Pyhäsalmi Option)LENA Detector Design (Pyhäsalmi Option)

Liquid ScintillatorActive Mass = 50.8kt of LAB

Concrete Tank (+Steel Sheets) r = 16m, h = 100mWall Thickness = 60cmTotal Mass = 69.1kt of LAB

PMT Support StructureInner face at r = 14m, h = 96m

about 30,000 12‘‘-PMTswith Winston conesoptical coverage: 30%

Electronics Halldome of 15m height

Top Muon Vetovertical muon tracking

Water Cherenkov Veto4000 8´´PMTs, Dmin > 2mfast neutron shieldinclined muons

Egg-Shaped Cavernabout 200000 m3

Rock Overburden4000 mwe

Detector Lifetime foreseen: > 30 years


Cylindrical Tank in Egg-shaped CavernCylindrical Tank in Egg-shaped Cavern

Dcl= 71.2m Dcs= 44.6m


Choice of the Liquid ScintillatorChoice of the Liquid Scintillator

Properties of LABChemical dataChemical formulaMolecular weightDensityViscosityFlash Point

C18H30

2410.863 kg/l

4.2 cps140 °C

HMIS ratingsHealthFlammabilityReactivity

110

Optical parametersIndex of refractionAttenuation lengthAbsorption lengthAbs.-reemission lengthRayleigh scattering length

1.49

~15 m40 m60 m40 m

LAB (linear-alkyl-benzene) as solvent

+ 3g/l PPO (2,5-diphenyl-oxazole)

+ 20 mg/l Bis-MSB (1,4-bis-(o-methyl-styryl)-benzene)

add solutes:

non-radiative 280nm

non-radiative 390nm

Light emission 430nm, τ < 5ns

(see Whitepaper for discussion of other options PXE, DIN,…)


PMTs and Optical ModulesPMTs and Optical Modules

Properties 12’’ PMTOM front diameterOM apertureOM lengthPMT lengthLight cone lengthWeight

450 mm410 mm700 mm330 mm320 mm

30 kgMaximum currentHV requirement Power per OM

0.125 mA2.0 kV0.25 W

Effective optical coverage required: 30%(Winston cones increase effective area by factor 1.85)

Encapsulation: Protect against cleaning water Protect against pressure (13bar) Protect against gamma rays from

its own material


Read-out electronicsRead-out electronicsRequirements Possible Layout

Large dynamic range: single pe >100 pe

Time resolution: at 1ns level, e.g. for proton decay

High trigger rates: >1kHz for SN detection

Complete PMT pulse shapes (?) multi-particle tracking

DAQ Racks:FADCs

bundledcables

Softwaretrigger

PMTpreampHV-gener.

scaffolding

cable feed-throughs


Vertex Reconstruction (EVertex Reconstruction (Evv< 10MeV)< 10MeV)

Events with Evis < 10 MeV: point-like in space and time

Described by 5 coordinates: x,y,z, t0, Evis

Fit (neg. log likelihood) to: hit times of first photons #photons detected on each PMT (Npe = 220 at 1 MeV)

Difference True – Reconstructed Position

electrons @ 1MeV

Difference True – Reconstructed Energy

electrons @ 1MeV


Multi-flavor detection of SN neutrinosMulti-flavor detection of SN neutrinos

Event rates for “standard“ SN of8M, <E>=14MeV at galactic center:

~104 e inverse beta decay

a few 103 p-scattering, NC @ 12C

a few 102 e e-scattering, CC @ 12C

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Astrophysics observe initial neutronization burst time-resolved cooling phase observe explosion shock-wave trigger for grav. waves, SNEWS

Neutrino physics mass hierarchy Earth and SN matter effects collective oscillations (low threshold and good E/E) ee conversion in NB more exotic phenomena

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Kate Scholberg, TAUP2011 Golden Channel: Inverse Beta DecayObservation of vµ,τ


Expected rate: 2-20 e /(50 kt yrs)(in energy window from 10-25MeV)

(First) Detection of DSNB flux(First) Detection of DSNB flux

Isotropic flux of all SN‘s emittedin the history of the Universe.

Faint signal: ≈ 102 /cm2s

Detection of e by inverse decay

Remaining background sources reactor and atmospheric e‘s cosmogenic backgrounds

Scientific gain first detection of DSNB information on average SN spectrum

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DSNB Flux at LENADSNB Flux at LENA

DSNB Signal Spectra in LENA:Assumed total energy 0.5 x 1053ergMaxwell-Boltzmann (MB) emission spectra


Geo-Neutrinos: The Earth heat flow problemGeo-Neutrinos: The Earth heat flow problem

Surface measurement: thermal power = 47 ± 2 TWModels: heat from radioactive decays of U, Th, K = 12-30 TW.

Is there a difference? And what accounts for the deficit?

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Geo-Neutrinos in LENAGeo-Neutrinos in LENA

IBD threshold of 1.8 MeVe from U/Th decay chains

At Pyhäsalmi expected geo- rate: 2x103 reactor- background: 7X102

What can we learn? contribution of U/Th decays to Earth‘s total heat flow 1% relative ratio of U/Th 5% with several detectors at different sites: disentangle oceanic/continental crust test for hypothetical georeactor

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U

U+Th

reactor bg


Neutrino oscillometryNeutrino oscillometryConcept: Short-baseline oscillation experiments using neutrinos from radioactive sources.

Radioactive neutrino sources e (monoenergetic) from EC sources: 51Cr, 37Ar e (E=1.8-2.3MeV) from 90Sr (90Y) large activity necessary: 1MCi or more

Oscillation baseline for m2

32 (13): 750m for 51Cr (747keV) for m2

41 (sterile): 1.3m

Scientific objectives check Pee(r) check CPT for and very sensitive in sterile searches (sin22≈10-3)

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„„high energy“ event reconstruction (sub-GeV, GeV)high energy“ event reconstruction (sub-GeV, GeV)

Track length in Liquid Scintillator: few 10cm – few m

Reconstruct track direction using time information of light front

(Borexino: angular resolution of 3o

for muons crossing scintillator volume)


Tracking in the sub-GeV rangeTracking in the sub-GeV rangeUse patterns of first photon arrival times + integrated charge per PMT

Charge seen by each PMT Time of first photon(time of flight corrected)

Example: 500 MeV muon


300 MeV muons created in the center of the detector, horizontal direction

Reconstruction of starting point:

Direction Energy


Tracking in the 1-5 GeV rangeTracking in the 1-5 GeV range

Work in progress: Use individual pulse shapes from each PMT

Example: Backtracking method


LENA as Far Detector for Neutrino Beam LENA as Far Detector for Neutrino Beam

Cern - Pyhäsalmi Cern - Frejus


Background from NC eventsBackground from NC events

+ (44%) → looking for µ+, tagging efficiency 86%

0, but no + (32%) → multivariate analysis (boosted decision trees)

e±, , 0,± or heavier, but not 0,+ (1.7%)

Pure (7%) → pulse shape

p, n (15%) → pulse shape

Recognition of NC background is a challenge v + X → v + X* + other particles

Conservative assumption (for electrons): NC 11%, CC 27%More optimistic (for electrons): NC 10%, CC 50%


CP Violation (Cern – Pyhäsalmi)CP Violation (Cern – Pyhäsalmi)

50kt10 years running

Energy resolution 5%

mass density along beamline: error≈ 1%


Mass Hierarchy (Cern – Pyhäsalmi)Mass Hierarchy (Cern – Pyhäsalmi)

50kt10 years running

Energy resolution 5%

mass density along beamline: error≈ 1%


SummarySummary

• LAGUNA/Liquid Scintillator (LENA) optimized for Neutrino Detection in the MeV energy range

• Extremely rich physics program includesSupernova Neutrinos, Solar Neutrinos, Geo Neutrinos,Reactor Neutrinos, Neutrino Oscillometry, Indirect Dark Matter Searches, Proton Decay.

• Significant progress with tracking in the GeV energy range.Work on neutral current background is ongoing.

• LENA as far detector in a neutrino beam (Cern-Pyhäsalmi)has potential to discover mass hierarchy at 5σ.

Caren Hagner 15.5.2012 LENA: Low Energy Neutrino Astronomy The LAGUNA Liquid Scintillator Detector...

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