LENALENA
Low Energy Neutrino Astrophysics
F F.von Feilitzsch, L. Oberauer, W. Potzel
Technische Universität München
LENA Delta
LENALENA
(Low Energy Neutrino Astrophysics)(Low Energy Neutrino Astrophysics)
Idea: A large (~30 kt) liquid scintillator Idea: A large (~30 kt) liquid scintillator underground detectorunderground detector forfor
Galactic supernova Galactic supernova neutrino detectionneutrino detection
Relic supernovae Relic supernovae neutrino detectionneutrino detection
Terrestrial neutrino detection
Search for Proton Decay
Solar Neutrino Spectroscopy
Neutrino properties
P - decay event
Scintillator: PXE , non hazard, flashpoint 145° C, density 0.99, Scintillator: PXE , non hazard, flashpoint 145° C, density 0.99, ultrapure (as proven in Borexino design studies)ultrapure (as proven in Borexino design studies)
Npe ~ 100 / MeV beta
H2O Cerenkov veto
30 KT scintillator
Possible locations for LENA ?Possible locations for LENA ?
Underground mine
~ 1450 m depth, low radioactivity, low reactor background !
Access via trucks
•loading of detector via pipeline
• transport of 30 kt PXE via railway
•no fundamental security problem with PXE !
• no fundamental problem for excavation
• standard technology (PM-encapsulation, electronics etc.)
• LENA is feasible in Pyhäsalmi !LENA is feasible in Pyhäsalmi !
Pylos (Nestor Institute) in Greece, Pylos (Nestor Institute) in Greece,
on the Cern Neutrino beam (off axis) D~1700 kmon the Cern Neutrino beam (off axis) D~1700 km
Neutrino interactions in the scintillator
υ elastic scattering
υ(x) + e υ(x) + e
υ (x) + p υ(x) + p
ν- inverse ß-decay
_
ν(e) + p n + e(+)
υ nuclear excitation
12C
12B12N
17.3 MeV13.4MeV
15.1MeV
1+ 20ms1+ 11ms1+
ec delayed coincidence
υ(e) interaction
υ(x) interaction
Galactic Supernova neutrino detection with Lena
protons). off scattering (elastic (6)
electrons) off scattering (elastic (5)
MeV) 15.1 E(Q CC with (4)
MeV) 17.3 (Q (3)
MeV) 13.4(Q (2)
MeV) 1.8 (Q (1)
x
xx
12*12*1212x
1212e
1212
pp
ee
CC
NeC
BeC
nep
x
x
e
e
Electron Antineutrino spectroscopy
Electron spectroscopy ~ 65~ 65
Neutral current interactions; info on all flavours
~ 4000 and ~ 2200~ 4000 and ~ 2200
~7800~7800
~ 480~ 480
Event rates for a SN type IIa in the galactic center (10 kpc)Event rates for a SN type IIa in the galactic center (10 kpc)
Visible proton recoil spectrum in a liquid scintillator
all flavors
and anti-particles
dominate
J. Beacom, astro-ph/0209136
Supernova neutrino luminosity (rough sketch)Supernova neutrino luminosity (rough sketch)
Relative size of the different luminosities is not well known: it depends on uncertainties of the explosion mechanism and the equation of state of hot neutron star matter
T. Janka, MPA
SNN-detection and neutrino oscillations with LENA
Dighe, Keil, Raffelt (2003)
Modulations in the energy spectrum due to matter effects in the Earth
Scintillator
good resolution
Water Cherenkov
Dighe, Keil, Raffelt (2003)
SNN-detection and neutrino oscillations
SNN-detection and neutrino oscillations
Modulations in the energy spectrum due to matter effects in the Earth
Preconditions for observation of those modulations
• SN neutrino spectra e and are different
• distance L in Earth large enough
• very good statistics
• very good energy resolution
LENA and relic Supernovae Neutrinos
• SuperK limit very close to theoretical expectations
• Threshold reduction from ~19 MeV (SuperK) to ~ 9 MeV with LENA __
• Method: delayed coincidence of e p e(+) n
• Low reactor neutrino background !
Information about early star formation period
SRN
No background for LENA !
Reactor SK
Reactor bg LENA !
Atmospheric neutrinos
LENA SNR rate: LENA SNR rate:
~ 6 counts/y~ 6 counts/y
Solar Neutrinos and LENA:Solar Neutrinos and LENA:
Probes for Density Profile Fluctuations !Probes for Density Profile Fluctuations !
7-Be~200 / h LENA
Balantekin, Yuksel
TAUP 2003
hep-ph/0303169
Terrestrische Neutrinos Terrestrische Neutrinos und LENA und LENA
• was ist die Quelle des terrestrischen Wärmeflusses?
• welchen Beitrag liefert die Radioaktivität?
• wieviel U, Th ist im Mantel?
• ist ein gigantischer natürlicher Kernreaktor im Zentrum die Energiequelle des Erdmagnetfelds?
Wärmefluss aus Wärmefluss aus der Erdeder Erde
•Es wird ein kleiner Wärmefluss aus der Erde gemessen.
80 mW / m80 mW / m22
•Integral:
HHEE 4 10 4 1013 13 W = 40 TWW = 40 TW
(Unsicherheit ~20%):•Das entspricht der Leistung von etwa 104 Kernkraftwerken!
• Die Kruste und der oberste Teil des Mantels sind einer direkten geochemischen Analyse zugänglich.
• Die Theorie: U, K und Th sind “lithophil”, sie akkumulieren in der (kontinentalen) Kruste.
• Danach könnte die ~30 km Kruste soviel U, Th wie der ~3000 km dicke Mantel enthalten.
• U, Th im unteren Teil des Mantels wird extrapoliertextrapoliert von Daten aus dem oberen Mantel.
Wo befindet sich U, Wo befindet sich U, Th?Th?
• U In der (kont.) Kruste
Mc(U) (0.2-0.4)1017 kg.
• Noch größere Unsicherheiten für den Mantel:
Mm(U) (0.2-0.8)1017Kg ??
crust
Upper mantle
KAMLAND: ein erster Blick…KAMLAND: ein erster Blick…
•6 Monate Daten ergibt einen Fit für N(Th+U)N(Th+U) für E< 2.6 MeV •N(Th+U) = 9 N(Th+U) = 9 6* 6*
•Die Unsicherheit* ist dominiert durch Fluktuation der Reaktorsignale•Das Ergebnis ist mit jedem geophysikalischen Modell konsistent: Hrad=(0-100 TW).
Proton Decay and LENAProton Decay and LENA
p K p K • This decay mode is favoured in SUSYSUSY theories
• The primary decay particle K is invisible in Water Cherenkov detectors
• It and the K-decay particles are visible in scintillation detectors
• Better energy solution further reduces background
P P KK+ + event event structure:structure: T (K+) = 105 MeV
nsec
KK++ 63.5 %) K63.5 %) K++
T (+) = 152 MeV T (+) = 108 MeV electromagnetic shower
E = 135 MeV
ee++ s) s) MeV)
ee++ s)s)
•3 - fold coincidence !3 - fold coincidence !
•the first 2 events are monoenergetic !the first 2 events are monoenergetic !
•use time- and position correlation !use time- and position correlation !
How good can one separate the How good can one separate the
first two events ?first two events ?
....results of a first Monte-Carlo calculation....results of a first Monte-Carlo calculation
K
time (nsec)
K
P decay into K and
Signal in LENA
Background
Rejection:
• monoenergetic K- and -signal!
• position correlation
• pulse-shape analysis
(after correction on
reconstructed position)
• SuperKamiokandeSuperKamiokande has 170 170 background events in 1489 1489 days (efficiency 33% 33% ))
•In LENALENA, this would scale down to a background of ~ 5 / y~ 5 / y and
after PSD-analysis this could be suppressed in LENALENA to
~ ~ 0.25 / y0.25 / y ! (efficiency ~ ~ 70%70% )
•A 30 kt detector (~ 10103434 protons as target) would have a
sensitivity of a few 10 a few 103434 years years for the K-decayK-decay after ~10 years measuring time
•The minimal SUSYSUSY SU(5) SU(5) model predicts the K-decayK-decay mode to be dominantdominant with a partial lifetime varying from 10102929y to 10y to 1035 35 yy !
actual best limit from SKSK: 6.7 x 1032 y (90% cl)
Conclusions• LENALENA a new observatory
• complemntary to high energy neutrino astrophysics
• fundamental impact on e.g. geophysics, astrophysics, neutrino physics, proton decay
• feasibiluty studies very promising (Pyhäsalmi)Pyhäsalmi)
• costs ca. 100 - 200 M€