Transcript Document 7310518

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
4 p  He  2e  2 e  26.7 MeV
4

Neutrino Energy in MeV
L. Oberauer, TUM
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, 2007
L. Oberauer, TUM
Neutrino elastic scattering off
electrons
Cross section for e is larger (factor ~5) as for m,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
External Labs
Shielding
~3500 m.w.e
Borexino Detector and Plants
BOREXINO Detector layout
Scintillator:
270 t PC+PPO in a 150 mm
thick nylon vessel
Nylon vessels:
Inner: 4.25 m
Outer: 5.50 m
Stainless Steel Sphere:
2212 PMTs +
concentrators
1350 m3
Water Tank:
g and n shield
m water Č detector
208 PMTs in water
2100 m3
Excellent
shielding of
external
background
Carbon steel plates
Increasing purity
from outside to the
central region
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 7Beneutrino 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
Borexino
Survival
probability at
Earth for solar
e as function
of their energy
Measurements
and
expectations
(MSW effect)
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…)
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
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)
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
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
[email protected]
http://www.e15.physik.tu-muenchen.de/research/lena.html
DSNB Detection via inverse
beta decay

Free protons as target
e  p  e  n

• Threshold 1.8 MeV
Delayed signal
(~200 ms)
Prompt signal
• E ~ Ee - Q ( spectroscopy)
• suppress background via delayed coincidence method
n + p -> D + g (2.2 MeV)
• position reconstruction => fiducial volume (suppress
external background)
Outline
DSNB
Background
LENA at Pyhäsalmi (Finland)
Event Rates
Spectroscopy
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  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 Q13 and mass
hierarchy (normal/inverted)
Coincidence with gravitational wave detectors
Solar Neutrino
Detection in LENA
Solar Neutrinos and LENA
  e ->   e
and
13C
+ e -> 13N + e
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 e -> e transitions
LENA and
neutrinos from the
Earth
Signal & Backgrounds in LENA
~ 1500 per year signal
 ~ 240 per year in [1.8 MeV – 3.2
MeV] from reactor neutrinos
Can be
statistically
 < 30 per year due to 210Po alpha
subtracted
13
-n reaction on C (Borexino purity
assumed)
 ~ 1 per year due to cosmogenic
background
(9Li - beta-neutron cascade)

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