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

Solar Neutrinos

Neutrino Energy in MeV

MeV7.2622He4 4 eep

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, 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

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:

0910

2984

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 Münchenmwurm@ph.tum.de

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

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 and mass

hierarchy (normal/inverted) Coincidence with gravitational wave detectors

Solar Neutrino Detection in LENA

Solar Neutrinos and LENAe 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 eetransitions

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 < 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

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