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 - cycleThe dominating solar pp - cycle
pp - 1 pp -2 pp -3
H. Bethe
W. Fowler
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
BOREXINO
Neutrino electron scattering e 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, 2007L. Oberauer, TUM
Neutrino elastic scattering off electrons
Cross section for e is larger (factor ~5) as for
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
LaboratoriNazionali del Gran Sasso LNGS
Shielding~3500 m.w.e
Borexino Detector and Plants
External Labs
BOREXINO Detector layout
Water Tank: and n shield water Č detector208 PMTs in water2100 m3
Carbon steel plates
Scintillator:270 t PC+PPO in a 150 m thick nylon vessel
Stainless Steel Sphere:2212 PMTs +
concentrators1350 m3
Nylon vessels:Inner: 4.25 mOuter: 5.50 m
Excellent shielding of external background
Increasing purity from outside to the central region
L. Oberauer, TUM
Results on solar 7Be neutrinos
Counting rate on solar 7Be-neutrinos: 49 ± 349 ± 3stat stat ± 4± 4sys sys /(d 100t)/(d 100t)
L. Oberauer, TUM
Results on solar 8B - neutrinos
No neutrino mixing
neutrino mixing plus (MSW) effect
New data for solar 8B neutrinosL. 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 ± 349 ± 3statstat ± 4 ± 4syssys / (d 100t) / (d 100t) Solar model (high metallicity, neutrino mixing,
MSW): 48 ± 4 / (d 100t)48 ± 4 / (d 100t) Solar model (low metallicity, neutrino mixing,
MSW): 44 ± 4 / (d 100t)44 ± 4 / (d 100t) Solar model, but no neutrino mixing:
74 ± 4 / (d 100t)74 ± 4 / (d 100t)
Clear confirmation of neutrino mixing and MSWL. 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
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 e as function of their energy
Measurements and expectations (MSW effect)
L. Oberauer, TUM
Borexino
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…) e measurement by e p -> e+ n
=> Geo neutrinos & reactor neutrinos Supernova neutrinos (~100 events) for a
galactic SN type II , limits on magnetic moment…
L. Oberauer, TUM
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)
Current best parameter values from solar neutrino experiments and KamLAND
= (34.06 + 1.16 – 0.84) degrees
m212 = (7.59 + 0.20 – 0.21) eV2
Three flavor neutrino oscillation analysis sin2= (2.00 + 2.09 - 1.63) x 10-2
Limit on : sin2< 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 theDiffuse 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 Mü[email protected]
http://www.e15.physik.tu-muenchen.de/research/lena.html
DSNB Detection via inverse beta decay Free protons as target
nepe • Threshold 1.8 MeV
• E~ Ee - Q ( spectroscopy)
• suppress background via delayed coincidence method
n + p D + (2.2 MeV)
• position reconstruction => fiducial volume (suppress external background)
Delayed signal (~200 s)
Prompt signal
LENA at Pyhäsalmi (Finland)
dependent on SN model
and on Supernova rate as function of redshift z
Number of events
20 – 200 (10 years)
DSN event rate in 10yrsinside the energy window
from 9.7 to 25 MeV
~25% of events are due to v’s originating from SN @ z>1
TU München
Outline DSNB Background Event Rates Spectroscopy
Excellent background rejectionEnergy 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)
Diffuse Supernova Neutrino Background Detection
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 spectrum with high precision Electron flux with ~ 10 % precision Total flux via neutral current reactions Separation of SN models Spectroscopy of all flavors Time evolution of neutrino burst Details of SN gravitational collapse Chance to separate low/high and mass
hierarchy (normal/inverted) Coincidence with gravitational wave detectors
Solar Neutrinos and LENA
High statistics in 7-Be Search for time fluctuations CNO and pep Test of MSW effect CC and NC measurements of 8-B Search for spectrum deformation Search for non-standard interactions Search for solar eetransitions
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)
K. Hochmuth et al., Astropart.Phys. 27 (2007) 21-29
Can be statistically subtracted
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: m2
12
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
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