Caren Hagner – LENA: Low Energy Neutrino Astronomy 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)

Caren Hagner – Physics Options at Low Energies Neutrino Sources  Galactic Supernova neutrinos 10 4 /SN  Diffuse Supernova neutrinos 10/yr  Solar neutrinos 10 4 /d  Geoneutrinos 10 3 /yr  Reactor neutrinos /yr  Neutrino oscillometry 10 4 /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

Caren Hagner – LENA Whitepaper just published Astroparticle Physics 35 (2012)

Caren Hagner – LENA Detector Design (Pyhäsalmi Option) Liquid Scintillator Active Mass = 50.8kt of LAB Concrete Tank (+Steel Sheets) r = 16m, h = 100m Wall Thickness = 60cm Total Mass = 69.1kt of LAB PMT Support Structure Inner face at r = 14m, h = 96m about 30,000 12‘‘-PMTs with Winston cones optical coverage: 30% Electronics Hall dome of 15m height Top Muon Veto vertical muon tracking Water Cherenkov Veto ´´PMTs, D min > 2m fast neutron shield inclined muons Egg-Shaped Cavern about m 3 Rock Overburden 4000 mwe Detector Lifetime foreseen: > 30 years

Caren Hagner – Cylindrical Tank in Egg-shaped Cavern D cl = 71.2mD cs = 44.6m

Caren Hagner – Choice of the Liquid Scintillator Properties of LAB Chemical data Chemical formula Molecular weight Density Viscosity Flash Point C 18 H kg/l 4.2 cps 140 °C HMIS ratings Health Flammability Reactivity Optical parameters Index of refraction Attenuation length Absorption length Abs.-reemission length Rayleigh scattering length 1.49 ~15 m 40 m 60 m 40 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,…)

Caren Hagner – PMTs and Optical Modules Properties12’’ PMT OM front diameter OM aperture OM length PMT length Light cone length Weight 450 mm 410 mm 700 mm 330 mm 320 mm 30 kg Maximum current HV requirement Power per OM mA 2.0 kV 0.25 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

Caren Hagner – Read-out electronics Requirements 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 bundled cables Software trigger PMT preamp HV-gener. scaffolding cable feed- throughs

Caren Hagner – Vertex Reconstruction (E v < 10MeV) Events with E vis < 10 MeV: point-like in space and time Described by 5 coordinates: x,y,z, t 0, E vis Fit (neg. log likelihood) to:  hit times of first photons  #photons detected on each PMT (N pe = 220 at 1 MeV) Difference True – Reconstructed Position 1MeV Difference True – Reconstructed Energy 1MeV

Caren Hagner – Multi-flavor detection of SN neutrinos Event rates for “standard“ SN of 8M , =14MeV at galactic center: ~ 10 4 e inverse beta decay a few 10 3  p-scattering, 12 C a few 10 2 e e-scattering, 12 C _ 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)  e  e conversion in NB  more exotic phenomena _ Kate Scholberg, TAUP2011 Golden Channel: Inverse Beta Decay Observation of v µ,τ

Caren Hagner – Expected rate: 2-20 e /(50 kt yrs) (in energy window from 10-25MeV) (First) Detection of DSNB flux Isotropic flux of all SN ‘s emitted in the history of the Universe. Faint signal:  ≈ 10 2 /cm 2 s 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 _ _ _

Caren Hagner – DSNB Flux at LENA DSNB Signal Spectra in LENA: Assumed total energy 0.5 x erg Maxwell-Boltzmann (MB) emission spectra

Caren Hagner – Geo-Neutrinos: The Earth heat flow problem Surface measurement: thermal power = 47 ± 2 TW Models: heat from radioactive decays of U, Th, K = TW. Is there a difference? And what accounts for the deficit? _

Caren Hagner – Geo-Neutrinos in LENA IBD threshold of 1.8 MeV e from U/Th decay chains At Pyhäsalmi  expected geo- rate:2x10 3  reactor- background:7X10 2 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 _ U U+Th reactor bg

Caren Hagner – Neutrino oscillometry Concept: Short-baseline oscillation experiments using neutrinos from radioactive sources. Radioactive neutrino sources  e (monoenergetic) from EC sources: 51 Cr, 37 Ar  e (E= MeV) from 90 Sr ( 90 Y)  large activity necessary: 1MCi or more Oscillation baseline  for  m 2 32 (  13 ): 750m for 51 Cr (747keV)  for  m 2 41 (sterile): 1.3m Scientific objectives  check P ee (r)  check CPT for and  very sensitive in sterile searches (sin 2 2  ≈ ) _ _

Caren Hagner – „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 3 o for muons crossing scintillator volume)

Caren Hagner – Tracking in the sub-GeV range Use 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

Caren Hagner – MeV muons created in the center of the detector, horizontal direction Reconstruction of starting point: DirectionEnergy

Caren Hagner – Tracking in the 1-5 GeV range Work in progress: Use individual pulse shapes from each PMT Example: Backtracking method

Caren Hagner – LENA as Far Detector for Neutrino Beam Cern - Pyhäsalmi Cern - Frejus

Caren Hagner – Background 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%

Caren Hagner – CP Violation (Cern – Pyhäsalmi) 50kt 10 years running Energy resolution 5% mass density along beamline: error ≈ 1%

Caren Hagner – Mass Hierarchy (Cern – Pyhäsalmi) 50kt 10 years running Energy resolution 5% mass density along beamline: error ≈ 1%

Caren Hagner – Summary LAGUNA/Liquid Scintillator (LENA) optimized for Neutrino Detection in the MeV energy range Extremely rich physics program includes Supernova 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 5 σ.