LENA Low Energy Neutrino Astronomy

1. LENALow Energy Neutrino Astronomy NOW 2010, September 6, 2010 Lothar Oberauer, TUM, Physik-Department

2. Liquid Scintillators are well known as neutrino targets Poltergeist ~ 1 t Double-Chooz ~ 10 t KamLAND ~ 1000 t SNO+ ~ 1000 t BOREXINO ~ 300 t

3. What’s about a ~ 50 kt Detector ? LENA – Low Energy Neutrino Astronomy (~50 kt deep underground detector) Hanohano (~10 kt deep ocean detector)

4. LENA Physics Goals • Proton Decay • Galactic Supernova Burst • Diffuse Supernova Neutrino Background • Long baseline neutrino oscillations • Solar Neutrinos • Geo neutrinos • Reactor neutrinos • Neutrino oscillometry • Atmospheric neutrinos • Dark Matter indirect search L. Oberauer, TUM

5. LENA and proton decay • High sensitivity to p -> K n (eff. ~ 68% instead 6% in SK t ~ 5 x 1034 y) • Sensitive to a variety of decay channels “invisible” modes, e.g. n -> n n n • For e.g. p -> e+p0 we expect ~ 1033 y (work in progress) T. Marrodan et al., Phys. Rev. D72, 075014 (2005) L. Oberauer, TUM

6. LENA and a galactic supernova

7. LENA and a Galactic Supernova Burst • Antielectron n spectrum with high precision • Electron n flux with ~ 10 % precision • Total flux via neutral current reactions • Separation of SN models • Spectroscopy of all n flavors • Sensitivity on deleptonization neutrinos • Time evolution of neutrino burst • Details of SN gravitational collapse • Chance to separate low/high Q13 and mass hierarchy (normal/inverted) • Coincidence with gravitational wave detectors L. Oberauer, TUM

8. LENA and the Diffuse Supernova Background • Excellent background rejection (nep->e+n) • Energy window 10 to 30 MeV. • High efficiency (100% with 50 kt target) • High discovery potential in LENA • ~2 to 20 events per year are expected (model dependent) M. Wurm et al., Phys.Rev.D 75 (2007) 023007 L. Oberauer, TUM

9. LENA and long baseline neutrino oscillations • Separation between e- and m-like events • Pulse shape discrimination (risetime, width) • Track reconstruction • Muon decay m -> e n n • Work in progress electrons (1.2 GeV) muons (1.2 GeV) L. Oberauer, TUM

10. Tracking in a scintillator detector • HE particles create along their track a lightfront very similar to a Cherenkov cone. • Single track reconstruction based on: • Arrival times of 1st photons at PMTs • Number of photons per PMT • Sensitive to particle types due tothe ratio of track length to visible energy. • Angular resolution of a few degrees,in principal very accurate energy resolution. • Work under progress for LENA and • scintillator LBNE option for DUSEL -- J. Learned, N. Tolich ... Monte-Carlo-study

11. CNGS neutrino induced muons in BOREXINO Water Cherenkov CERN 770km Scintillator Direction from CERN (azimuth = 0 degree) real Data – no Monte-Carlo ! BOREXINO is NOT optimized for tracking !

12. Study CERN – LENA at Pyhäsalmi (Finland) • CERN - Pyhäsalmi 2288 km • 5 years nu + 5 years anti-nu • 1. Maximum @ 4.2 GeV • Wide band beam 1 – 6 GeV • 1.5 MW power • Sensitivity on theta_13, CP-parameter, mass hierarchy J. Peltoniemi, Simulations of neutrino oscillations for a wide band beam from CERN to LENA, arXiv:0911.4876v1 [hep-ex] L. Oberauer, TUM

13. Mass Hierarchy preliminary CP - phase > 3 Sigma Log( sin(2Q13))**2

14. LENA and Solar Neutrinos • High statistics in 7-Be (~ 5400 events per day) • Search for small time fluctuations • CNO and pep n (~ 360 events per day) • Very sensitive test of MSW effect • CC and NC measurements of 8-B • Search for spectrum deformation • Search for non-standard n interactions • Search for solar ne -> netransitions L. Oberauer, TUM

15. LENA and Geo-neutrinos • LENAis the only detector within Laguna able to determine the geo neutrino flux • In LENA we expect between 300 to 3000 events per year (“best bet” ~ 1500 / year) • Good signal / background ratio most significant contribution can be subtracted statistically • Separation of geological models together with other detectors L. Oberauer, TUM

16. LENA and Reactor neutrinos • At Frejus ~ 17,000 events per year • High precision on solar oscillation parameter: • Dm212~ 1% • Q12 ~ 10% S.T. Petcov, T. Schwetz, Phys. Lett. B 642, (2006), 487 J. Kopp et al., JHEP 01 (2007), 053 L. Oberauer, TUM

17. Scintillator R&D • Light yields • Fluorescence times and spectra • Attenuation lengths • Scattering lengths • Development of an optical model for Monte-Carlo simulations attenuation length

18. PXE, C16H18 density: 0.99 kg/l light yield:ca. 10.000 ph/MeV fluorescence decay:2.6ns attenuation length: ≤12m (purified) scattering length: 23m +80% Dodecane, C12H26 density: 0.80 kg/l light yield: ca. 85% fluorescence decay slower attenuation length: >12m scattering length: 33m Solvent Candidates LAB, C16-19H26-32 density: 0.86 kg/l light yield: comparable fluorescence decay:5.2ns attenuation length: <20m scattering length: 25m • Detector diameter of 30m (or even more) is well feasible! • Fluorescence times (3-5ns) and light yield (200-500pe/MeV) depend on the solvent. • LAB is currently favored.

19. Pre-feasibility study for LENA at Pyhäsalmi (TUM and company Rockplan, Finland) • Depth at 1400 m – 1500 m possible ! • Geological study completed • Vertical detector position • Logistics (Vent, Electricity, etc.) considered • Construction time of cavern ~ 4 years • 1st costs estimate for the whole project • Tank feasibility study (accomplished May 2010) L. Oberauer, TUM

20. favoured option: + Tank Construction: 8 years L. Oberauer, TUM

21. Conclusions • Scintillator techniques for neutrino physics are very important • Reactor-, Solar-, Geo-neutrino experiments • Future: Extension to DSNB, Supernova-n, Proton-Decay, Long-Baseline n-Oscillations • Rich R&D-program still on-going • First feasibility studies successfully accomplished • “White paper” under preparation L. Oberauer, TUM