LENA Low Energy Neutrino Astronomy The LAGUNA Liquid

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 – 15. 5. 2012

Physics 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 Low energy threshold, Radiopurity Substantial progress with event reconstruction at few 100 Me. V – few Ge. V: § Long Baseline Neutrino Observation possible → mass hierarchie Caren Hagner – 15. 5. 2012

LENA Whitepaper just published Astroparticle Physics 35 (2012) 685 -732 Caren Hagner – 15. 5. 2012

LENA Detector Design (Pyhäsalmi Option) Electronics Hall dome of 15 m height Liquid Scintillator Active Mass = 50. 8 kt of LAB Top Muon Veto vertical muon tracking Concrete Tank (+Steel Sheets) r = 16 m, h = 100 m Wall Thickness = 60 cm Total Mass = 69. 1 kt of LAB Water Cherenkov Veto 4000 8´´PMTs, Dmin > 2 m fast neutron shield inclined muons PMT Support Structure Inner face at r = 14 m, h = 96 m Egg-Shaped Cavern about 200000 m 3 about 30, 000 12‘‘-PMTs with Winston cones optical coverage: 30% Rock Overburden 4000 mwe Caren Hagner – 15. 5. 2012 Detector Lifetime foreseen: > 30 years

Cylindrical Tank in Egg-shaped Cavern Dcl= 71. 2 m Caren Hagner – 15. 5. 2012 Dcs= 44. 6 m

Choice of the Liquid Scintillator LAB (linear-alkyl-benzene) as solvent add solutes: + 3 g/l PPO (2, 5 -diphenyl-oxazole) + 20 mg/l Bis-MSB (1, 4 -bis-(o-methyl-styryl)-benzene) Light emission 430 nm, τ < 5 ns (see Whitepaper for discussion of other options PXE, DIN, …) Caren Hagner – 15. 5. 2012 non-radiative 280 nm non-radiative 390 nm Properties of LAB Chemical data Chemical formula Molecular weight Density Viscosity Flash Point HMIS ratings Health Flammability Reactivity Optical parameters Index of refraction Attenuation length Absorption length Abs. -reemission length Rayleigh scattering length C 18 H 30 241 0. 863 kg/l 4. 2 cps 140 °C 1 1 0 1. 49 ~15 m 40 m 60 m 40 m

PMTs and Optical Modules Effective optical coverage required: 30% (Winston cones increase effective area by factor 1. 85) Encapsulation: § Protect against cleaning water § Protect against pressure (13 bar) § Protect against gamma rays from its own material Properties OM front diameter OM aperture OM length PMT length Light cone length Weight Maximum current HV requirement Power per OM Caren Hagner – 15. 5. 2012 12’’ PMT 450 mm 410 mm 700 mm 330 mm 320 mm 30 kg 0. 125 m. A 2. 0 k. V 0. 25 W

Read-out electronics Requirements Possible Layout § Large dynamic range: single pe >100 pe Software trigger § Time resolution: at 1 ns level, e. g. for proton decay DAQ Racks: FADCs § High trigger rates: >1 k. Hz for SN detection § Complete PMT pulse shapes (? ) multi-particle tracking cable feedthroughs bundled cables PMT preamp HV-gener. scaffolding Caren Hagner – 15. 5. 2012

Vertex Reconstruction (Ev< 10 Me. V) Events with Evis < 10 Me. V: point-like in space and time Described by 5 coordinates: x, y, z, t 0, Evis Fit (neg. log likelihood) to: § hit times of first photons § #photons detected on each PMT (Npe = 220 at 1 Me. V) Difference True – Reconstructed Position electrons @ 1 Me. V Caren Hagner – 15. 5. 2012 Difference True – Reconstructed Energy electrons @ 1 Me. V

Multi-flavor detection of SN neutrinos Kate Scholberg, TAUP 2011 Golden Channel: Inverse Beta Decay Observation of vµ, τ Astrophysics § observe initial neutronization burst § time-resolved cooling phase § observe explosion shock-wave § trigger for grav. waves, SNEWS Neutrino physics Event rates for “standard“ SN of 8 M , <E>=14 Me. V at galactic center: _ ~104 ne inverse beta decay a few 103 nm, t np-scattering, NC @ 12 C a few 102 ne ne-scattering, CC @ 12 C Caren Hagner – 15. 5. 2012 § mass hierarchy § Earth and SN matter effects § collective oscillations (low threshold and good DE/E) _ § ne ne conversion in NB § more exotic phenomena

(First) Detection of DSNB flux Isotropic flux of all SNn‘s emitted in the history of the Universe. Faint signal: Fn ≈ 102 /cm 2 s _ Detection of ne by inverse b decay Remaining background sources _ § reactor and atmospheric ne‘s § cosmogenic backgrounds Scientific gain § first detection of DSNB § information on average SNn spectrum Caren Hagner – 15. 5. 2012 _ Expected rate: 2 -20 ne /(50 kt yrs) (in energy window from 10 -25 Me. V)

DSNB Flux at LENA DSNB Signal Spectra in LENA: Assumed total energy 0. 5 x 1053 erg Maxwell-Boltzmann (MB) emission spectra Caren Hagner – 15. 5. 2012

Geo-Neutrinos: The Earth heat flow problem _ Surface measurement: thermal power = 47 ± 2 TW Models: heat from radioactive decays of U, Th, K = 12 -30 TW. Is there a difference? And what accounts for the deficit? Caren Hagner – 15. 5. 2012

Geo-Neutrinos in LENA IBD threshold of 1. 8 Me. V _ ne from U/Th decay chains At Pyhäsalmi § expected geo-n rate: § reactor-n background: U+Th U reactor bg Caren Hagner – 15. 5. 2012 2 x 103 7 X 102 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

Neutrino oscillometry Concept: Short-baseline oscillation experiments using neutrinos from radioactive sources. Radioactive neutrino sources § ne (monoenergetic) from EC sources: 51 Cr, 37 Ar _ § ne (E=1. 8 -2. 3 Me. V) from 90 Sr (90 Y) § large activity necessary: 1 MCi or more Oscillation baseline § for Dm 232 (q 13): § for Dm 241 (sterile): 750 m for 51 Cr (747 ke. V) 1. 3 m Scientific objectives § check Pee(r) _ § check CPT for n and n § very sensitive in sterile n searches (sin 22 q ≈10 -3) Caren Hagner – 15. 5. 2012

„high energy“ event reconstruction (sub-Ge. V, Ge. V) Track length in Liquid Scintillator: few 10 cm – few m Reconstruct track direction using time information of light front (Borexino: angular resolution of 3 o for muons crossing scintillator volume) Caren Hagner – 15. 5. 2012

Tracking in the sub-Ge. V range Use patterns of first photon arrival times + integrated charge per PMT Example: 500 Me. V muon Charge seen by each PMT Caren Hagner – 15. 5. 2012 Time of first photon (time of flight corrected)

300 Me. V muons created in the center of the detector, horizontal direction Reconstruction of starting point: Direction Caren Hagner – 15. 5. 2012 Energy

Tracking in the 1 -5 Ge. V range Example: Backtracking method Work in progress: Use individual pulse shapes from each PMT Caren Hagner – 15. 5. 2012

LENA as Far Detector for Neutrino Beam Cern - Pyhäsalmi Caren Hagner – 15. 5. 2012 Cern - Frejus

Background from NC events Recognition of NC background is a challenge v + X → v + X* + other particles § p+ (44%) → looking for µ+, tagging efficiency 86% § p 0, but no p+ (32%) → multivariate analysis (boosted decision trees) § e±, g, K 0, ± or heavier, but not p 0, + (1. 7%) § Pure p- (7%) → pulse shape § p, n (15%) → pulse shape Conservative assumption (for electrons): NC 11%, CC 27% More optimistic (for electrons): NC 10%, CC 50% Caren Hagner – 15. 5. 2012

CP Violation (Cern – Pyhäsalmi) 50 kt 10 years running Energy resolution 5% mass density along beamline: error≈ 1% Caren Hagner – 15. 5. 2012

Mass Hierarchy (Cern – Pyhäsalmi) 50 kt 10 years running Energy resolution 5% mass density along beamline: error≈ 1% Caren Hagner – 15. 5. 2012

Summary • LAGUNA/Liquid Scintillator (LENA) optimized for Neutrino Detection in the Me. V 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 Ge. V 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