LENA

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LENA
LENA Delta

• Low Energy Neutrino Astrophysics

F F.von Feilitzsch, L.
Oberauer, W. Potzel

Technische Universität München
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LENA (Low Energy Neutrino Astrophysics)
Idea A large (30 kt) liquid scintillator
underground detector for
Relic supernovae neutrino detection
Search for Proton Decay
Galactic supernova neutrino detection
Neutrino properties
Terrestrial neutrino detection
Solar Neutrino Spectroscopy
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H2O
Cerenkov veto
Npe 100 / MeV beta
30 KT scintillator
P - decay event
Scintillator PXE , non hazard, flashpoint 145
C, density 0.99, ultrapure (as proven in Borexino
design studies)
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Possible locations for LENA ?
Underground mine 1450 m depth, low
radioactivity, low reactor n-background !
Access via trucks
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• 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 !

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Pylos (Nestor Institute) in Greece, on the Cern
Neutrino beam (off axis) D1700 km
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Neutrino interactions in the scintillator

• ? elastic scattering
• ?(x) e ? ?(x) e
• ? (x) p ? ?(x) p
• ?- inverse ß-decay
• _
• ?(e) p ? n e()

• ? nuclear excitation

15.1MeV
?(x) interaction
1 11ms
1
1 20ms
12N
12B
?(e) interaction
17.3 MeV
13.4MeV
ec delayed coincidence
12C
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Galactic Supernova neutrino detection with Lena
Electron Antineutrino spectroscopy
   
7800
Electron n spectroscopy 65
480

• Neutral current interactions info on all
  flavours 4000 and 2200

Event rates for a SN type IIa in the galactic
center (10 kpc)
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Visible proton recoil spectrum in a liquid
scintillator
all flavors
nm, nt and anti-particles dominate
J. Beacom, astro-ph/0209136
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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
Supernova neutrino luminosity (rough sketch)
T. Janka, MPA
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SNN-detection and neutrino oscillations with LENA
Modulations in the energy spectrum due to matter
effects in the Earth
Dighe, Keil, Raffelt (2003)
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SNN-detection and neutrino oscillations
Water Cherenkov
Scintillator good resolution
SNN-detection and neutrino oscillations
Modulations in the energy spectrum due to matter
effects in the Earth
Dighe, Keil, Raffelt (2003)
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Preconditions for observation of those modulations

• SN neutrino spectra ne and nm,t are different
• distance L in Earth large enough
• very good statistics
• very good energy resolution

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• 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 ne p -gt e()
  n
• Low reactor neutrino background !
• ? Information about early star formation period
  

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Reactor SK
No background for LENA !
Reactor bg LENA !
LENA SNR rate 6 counts/y
SRN
Atmospheric neutrinos
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Solar Neutrinos and LENA Probes for Density
Profile Fluctuations !
Balantekin, Yuksel TAUP 2003 hep-ph/0303169
7-Be 200 / h LENA
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• Terrestrische Neutrinos 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?

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Wärmefluss aus der Erde

• Es wird ein kleiner Wärmefluss aus der Erde
  gemessen.
• F 80 mW / m2
• Integral
• HE 4 1013 W 40 TW
• (Unsicherheit 20)
• Das entspricht der Leistung von etwa 104
  Kernkraftwerken!

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Wo befindet sich U, Th?

• 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
  extrapoliert von Daten aus dem oberen Mantel.

• 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 ?

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KAMLAND ein erster Blick

• 6 Monate Daten ergibt einen Fit für N(ThU) für
  Elt 2.6 MeV
• N(ThU) 9 6
• Die Unsicherheit ist dominiert durch
  Fluktuation der Reaktorsignale
• Das Ergebnis ist mit jedem geophysikalischen
  Modell konsistent Hrad(0-100 TW).

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• Proton Decay and LENA
• p K n
• This decay mode is favoured in SUSY 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

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P -gt K n event structure
T (K) 105 MeV
t (K) 12.8 nsec K -gt m n
(63.5 ) K -gt p p0 (21.2 ) T
(m) 152 MeV T (p) 108 MeV
electromagnetic shower
E 135 MeV m -gt e
n n (t 2.2 ms) p -gt m n (T 4
MeV) m -gt e n n (t 2.2 ms)
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• 3 - fold coincidence !
• the first 2 events are monoenergetic !
• use time- and position correlation !
• How good can one separate the
• first two events ?
• ....results of a first Monte-Carlo calculation

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P decay into K and n
m
m
K
K
time (nsec)
Signal in LENA
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• Background
• Rejection
• monoenergetic K- and m-signal!
• position correlation
• pulse-shape analysis
• (after correction on
• reconstructed position)

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• SuperKamiokande has 170 background events in
  1489 days (efficiency 33 )
• In LENA, this would scale down to a background of
  5 / y and after PSD-analysis this could be
  suppressed in LENA to
• 0.25 / y ! (efficiency 70 )
• A 30 kt detector ( 1034 protons as target)
  would have a sensitivity of t lt a few 1034
  years for the K-decay after 10 years measuring
  time
• The minimal SUSY SU(5) model predicts the K-decay
  mode to be dominant with a partial lifetime
  varying from 1029y to 1035 y !
• actual best limit from SK t gt 6.7 x 1032 y
  (90 cl)

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• Conclusions
• LENA 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)
• costs ca. 100 - 200 M

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...some more aspects of Lena Complementary to
high energy neutrino astronomy Long term
(decades) experiment Large European intiative