Neutrinos as Probes: Solar-, Geo-, Supernova neutrinos; Laguna

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

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

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The dominating solar pp - cycle
H. Bethe
W. Fowler
pp - 1
pp -2
pp -3
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The sub-dominant solar CNO - cycle
dominates in stars with more mass as our
sun gtLarge astrophysical relevance Measurement
of CNO neutrinos determination of inner solar
metallicity
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Solar Neutrinos
L. Oberauer, TUM
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BOREXINO
Neutrino electron scattering n e -gt n e
Liquid scintillator technology (300t) Low
energy threshold (60 keV) Good energy
resolution ( 5 _at_ 1 MeV) very low
background Sensitivity on sub-MeV
neutrinos Online since May 16th, 2007
L. Oberauer, TUM
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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
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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
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BOREXINO Detector layout
Stainless Steel Sphere 2212 PMTs
concentrators 1350 m3
Scintillator 270 t PCPPO in a 150 mm thick
nylon vessel
Water Tank g and n shield m water C 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
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Background in Borexino

• Muons
• leak rate Muon-Veto lt 0.5
• including pulse-shape Inner Detector lt 0.01
• Muon generated radionuclides (long lifetime gt 2
  sec)
• 11C 0.25 counts / (d t)
• 10C 5 x 10-3 counts / (d t)
• 11Be lt 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 lt 10-14 g/g
• 14C 2 x 10-18
• 85Kr 0.29 counts / (d t)

L. Oberauer, TUM
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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
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Results on solar 7Be neutrinos
Counting rate on solar 7Be-neutrinos 49 3stat
4sys /(d 100t)
L. Oberauer, TUM
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Results on solar 8B - neutrinos
No neutrino mixing neutrino mixing plus
(MSW) effect
New data for solar 8B neutrinos
L. Oberauer, TUM
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Systematic uncertainties
Calibration with radioactive sources (since
winter 2008/09) Study of response function (e.g.
gamma quenching, kb parameter)
L. Oberauer, TUM
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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
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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
  gt

L. Oberauer, TUM
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• Without solar luminosity constraint
• With solar luminosity constraint

CNO contribution to solar energy generation lt
5.4 (90 cl)
L. Oberauer, TUM
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Correlation between constraints on pp- and CNO-
fluxes
Borexino result and solar luminosity constraint
fCNO lt 4.8 (90 cl)
L. Oberauer, TUM
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Survival probability at Earth for solar ne as
function of their energy Measurements and
expectations (MSW effect)
Borexino
L. Oberauer, TUM
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Prospects of BOREXINO

• Improvement of systematical uncertainties
• 7Be flux measurement at lt 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 -gt e n
• gt Geo neutrinos reactor neutrinos
• Supernova neutrinos (100 events) for a galactic
  SN type II , limits on magnetic moment

L. Oberauer, TUM
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Search for Day/Night effect

• The Day Night asymmetry of signalbackground is
  zero within 1 sigma

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New Analysis of SNO phases I and II
Threshold at 3.5 MeV (nucl-ex09102984)
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• 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-ex09102984)

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Three flavor neutrino oscillation analysis
nucl-ex09102984
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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 lt 0.057 (95 cl)
• nucl-ex09102984

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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)

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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
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Search for theDiffuse Supernova Neutrino
Backgroundin 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 Münchenmwurm_at_ph.tu
m.de http//www.e15.physik.tu-muenchen.de/research
/lena.html
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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 -gt D g (2.2 MeV)
• position reconstruction gt fiducial volume
  (suppress external background)

Prompt signal
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LENA at Pyhäsalmi (Finland)
Outline DSNB
Background Event Rates
Spectroscopy
DSN event rate in 10yrsinside 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 vs originating from SN
_at_ zgt1
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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)

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Galactic Supernova neutrino burst in LENA
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(No Transcript)
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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
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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

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Solar Neutrino Detection in LENA
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Solar Neutrinos and LENA n e -gt n e and
13C ne -gt 13N e
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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 -gt ne transitions

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LENA and neutrinos from the Earth
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Sensitivity on U, Th
arbitrary units
Energy threshold 1st detection of Geo-neutrinos
in KamLAND in 2005 (1kt liquid scintillator
detector)
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Signal Backgrounds in LENA

• 1500 per year signal
• 240 per year in 1.8 MeV 3.2 MeV from
  reactor neutrinos
• lt 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
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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

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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
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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

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One Option
Tank Construction 8 years
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Conclusions

• Solar neutrino experiments very successful
• Strong impact on neutrino oscillation parameter
• Precise determination of solar nuclear fusion
  processes
• Missing CNO-neutrinos -gt 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