Neutrinos as Probes: Solar-, Geo-, Supernova neutrinos; Laguna MPIK Heidelberg, November 2009 Lothar Oberauer, Physikdepartment E15, TU München

Solar Neutrinos Borexino results SNO results What do we know now about solar neutrino branches ? What can we learn about neutrino oscillation parameter ?

The dominating solar pp - cycle H. Bethe W. Fowler pp - 1 pp -2 pp -3

The sub-dominant solar CNO - cycle …dominates in stars with more mass as our sun… =>Large astrophysical relevance Measurement of CNO neutrinos = determination of inner solar metallicity

Solar Neutrinos Neutrino Energy in MeV L. Oberauer, TUM

BOREXINO Neutrino electron scattering n e -> n e Liquid scintillator technology (~300t): Low energy threshold (~60 keV) Good energy resolution (~ 5% @ 1 MeV) very low background Sensitivity on sub-MeV neutrinos Online since May 16th, 2007 L. Oberauer, TUM

Neutrino elastic scattering off electrons Cross section for ne is larger (factor ~5) as for nm,t Expected rate without neutrino mixing ~ 74 counts per day and 100t target Expected rate with neutrino mixing (MSW-LMA) ~ 48 c/(d 100 t) L. Oberauer, TUM

BOREXINO in the Italian Gran Sasso Underground Laboratory in the mountains of Abruzzo, Italy, ~120 km from Rome Laboratori Nazionali del Gran Sasso LNGS Shielding ~3500 m.w.e External Labs Borexino Detector and Plants

BOREXINO Detector layout Stainless Steel Sphere: 2212 PMTs + concentrators 1350 m3 Scintillator: 270 t PC+PPO in a 150 mm thick nylon vessel Water Tank: g and n shield m water Č detector 208 PMTs in water 2100 m3 Nylon vessels: Inner: 4.25 m Outer: 5.50 m Excellent shielding of external background Increasing purity from outside to the central region Carbon steel plates L. Oberauer, TUM

Background in Borexino Muons leak rate Muon-Veto < 0.5 % including pulse-shape Inner Detector < 0.01 % Muon generated radionuclides (long lifetime > 2 sec) 11C = 0.25 counts / (d t) 10C ~ 5 x 10-3 counts / (d t) 11Be < 1.5 x 10-3 counts / (d t) Internal background Uranium = 1.6 x 10-17 g/g Thorium = 6.8 x 10-18 g/g Knat < 10-14 g/g 14C ~ 2 x 10-18 85Kr ~ 0.29 counts / (d t) L. Oberauer, TUM

Cuts for solar 7Be neutrinos Data taking 192 days lifetime Muon cut Radon delayed coincidences (Bi-Po and decays before incl. radon) Fiducial volume cut (~ 100 t target) Alpha/Beta separation by pulse shape analysis (optional) L. Oberauer, TUM

Results on solar 7Be neutrinos Counting rate on solar 7Be-neutrinos: 49 ± 3stat ± 4sys /(d 100t) L. Oberauer, TUM

Results on solar 8B - neutrinos No neutrino mixing neutrino mixing plus (MSW) effect New data for solar 8B neutrinos L. Oberauer, TUM

Systematic uncertainties Calibration with radioactive sources (since winter 2008/09) Study of response function (e.g. gamma quenching, kb – parameter…) L. Oberauer, TUM

Implications of solar 7Be neutrino result Borexino exp. result: 49 ± 3stat ± 4sys / (d 100t) Solar model (high metallicity, neutrino mixing, MSW): 48 ± 4 / (d 100t) Solar model (low metallicity, neutrino mixing, MSW): 44 ± 4 / (d 100t) Solar model, but no neutrino mixing: 74 ± 4 / (d 100t) Clear confirmation of neutrino mixing and MSW L. Oberauer, TUM

Implications of solar 7Be-neutrino result f = measured / expected (solar model, MSW) Before Borexino fBe = After Borexino fBe = New constraints on pp- and CNO-fluxes from BOREXINO and all other solar neutrino experiments => L. Oberauer, TUM

CNO contribution to solar energy generation Without solar luminosity constraint With solar luminosity constraint CNO contribution to solar energy generation < 5.4 % (90 % cl) L. Oberauer, TUM

Correlation between constraints on pp- and CNO- fluxes Borexino result and solar luminosity constraint fCNO < 4.8 (90 %cl) L. Oberauer, TUM

Survival probability at Earth for solar ne as function of their energy Measurements and expectations (MSW effect) Borexino L. Oberauer, TUM

Prospects of BOREXINO Improvement of systematical uncertainties 7Be flux measurement at < 5 % total uncertainty 8B flux measurement with increased statistics Measurement of pep and CNO-neutrinos (if 11C event rejection and purity allows…) ne measurement by ne p -> e+ n => Geo neutrinos & reactor neutrinos Supernova neutrinos (~100 events) for a galactic SN type II , limits on magnetic moment… L. Oberauer, TUM

Search for Day/Night effect The Day Night asymmetry of signal+background is zero within 1 sigma

New Analysis of SNO phases I and II Threshold at 3.5 MeV (nucl-ex:09102984)

Two flavor neutrino oscillation hypothesis analysis Global fit including: Solar neutrino experimental results (SNO, Cl, Gallex/GNO, Sage, Borexino, SK I & II) KamLAND reactor neutrino data (SNO collaboration: nucl-ex:09102984)

Three flavor neutrino oscillation analysis nucl-ex:09102984

Three flavor neutrino oscillation analysis Current best parameter values from solar neutrino experiments and KamLAND Q12 = (34.06 + 1.16 – 0.84) degrees Dm212 = (7.59 + 0.20 – 0.21) eV2 Three flavor neutrino oscillation analysis sin2Q13 = (2.00 + 2.09 - 1.63) x 10-2 Limit on Q13: sin2Q13 < 0.057 (95% cl) nucl-ex:09102984

Prospects of low energy neutrino astronomy in Europe 3 large detector types are proposed 0.4 Mt Water Cherenkov (Memphis) 100 kt Liquid Argon (Glacier) 50 kt Liquid Scintillator (LENA) LAGUNA: design study for a future underground facility in Europe (report completed in 2010)

Physics Goals Proton Decay Long baseline neutrino oscillations Diffuse Supernova Neutrino Background Galactic Supernova Burst Solar Neutrinos Geo neutrinos Reactor neutrinos Atmospheric neutrinos Dark Matter indirect search T. Lachenmaier my talk today

Search for the Diffuse Supernova Neutrino Background in LENA Phys.Rev.D 75 (2007) 023007 M. Wurm, F. v. Feilitzsch, M. Göger-Neff, T. Marrodán Undagoitia, L. Oberauer, W. Potzel, J. Winter Technische Universität München mwurm@ph.tum.de http://www.e15.physik.tu-muenchen.de/research/lena.html

DSNB Detection via inverse beta decay Free protons as target Delayed signal (~200 ms) Threshold 1.8 MeV En ~ Ee - Q (n spectroscopy) suppress background via delayed coincidence method n + p -> D + g (2.2 MeV) position reconstruction => fiducial volume (suppress external background) Prompt signal

LENA at Pyhäsalmi (Finland) Outline DSNB Background Event Rates Spectroscopy LENA at Pyhäsalmi (Finland) DSN event rate in 10yrs inside the energy window from 9.7 to 25 MeV dependent on SN model and on Supernova rate as function of redshift z Number of events 20 – 200 (10 years) ~25% of events are due to v’s originating from SN @ z>1 TU München

Diffuse Supernova Neutrino Background Detection Excellent background rejection 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)

Galactic Supernova neutrino burst in LENA

Separation of SN models ? Yes! Possible independent from oscillation model due to neutral current reactions in LENA TBP KRJ LL 12-C: 700 950 2100 Nu-p: 1500 2150 5700 for 8 solar mass progenitor and 10 kpc distance

Supernova neutrinos with LENA 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 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

Solar Neutrino Detection in LENA

Solar Neutrinos and LENA n + e -> n + e and 13C + ne -> 13N + e

Solar Neutrinos and LENA High statistics in 7-Be Search for time fluctuations CNO and pep n 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 -> ne transitions

LENA and neutrinos from the Earth

Sensitivity on U, Th arbitrary units Energy threshold 1st detection of Geo-neutrinos in KamLAND in 2005 (1kt liquid scintillator detector)

Signal & Backgrounds in LENA ~ 1500 per year signal ~ 240 per year in [1.8 MeV – 3.2 MeV] from reactor neutrinos < 30 per year due to 210Po alpha -n reaction on 13C (Borexino purity assumed) ~ 1 per year due to cosmogenic background (9Li - beta-neutron cascade) Can be statistically subtracted K. Hochmuth et al., Astropart.Phys. 27 (2007) 21-29

LENA and Geo-neutrinos LENA is 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

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

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

One Option: + Tank Construction: 8 years

Conclusions Solar neutrino experiments very successful Strong impact on neutrino oscillation parameter Precise determination of solar nuclear fusion processes Missing CNO-neutrinos -> determination of solar inner metallicity Geo neutrinos (stay tuned !) Prospects (Large detectors like LENA) in this field & proton decay and long baseline experiments L. Oberauer, TUM