LENA

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LENA
LENA Delta

• Low Energy Neutrino Astrophysics

EL SUD Meeting Garching, April 24th
L. Oberauer, Technische Universität
München www.e15.physik.tu-muenchen.de/research/len
a.htlm
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LENA 50 kt liquid scintillator detector
100m
30m
Muon veto
30 coverage up to 60 (light cones)

• Scintillator solvent PXE, or PXE/mineral oil
  mixture
• non hazardous, flashpoint 145 C easy
  handling
• density up to 0.99 high self shielding
• high light yield low energy events
• low background level U, Th solar n, geo n,
  snr n

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LENA at CUPP

• transport of PXE via railway
• loading of detector via direct pipeline
• no fundamental security problem with PXE
• no fundamental problem for excavation
• LENA is feasible in Pyhäsalmi !

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Scintillator for LENA
CTF at Gran Sasso (BOREXINO) Absorption- and
Scattering lengths at TU München (M. Wurm
Diploma thesis)
Coverage 30
100 pe / MeV for an event at the center up to
200 pe / MeV with light cones should be
possible
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Physics goals

• Baryon number violation (Proton decay)
• Gravitational collapse (SN n detection)
• Star formation (diffuse SN n background)
• Thermonuclear fusion processes (low E solar
  neutrinos CNO, pep, 7Be)
• Geophysical models (U, Th n)
• Neutrino oscillations (Long baseline n)

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Supernovae Relic ne
3 models (different spectral shapes) Lawrence
Livermore LL Keil, Raffelt, Janka
KRJ Thompson, Burrows, Pinto - TBP
Large systematic uncertainties UV (blue), Ha
(green) and FIR (red) are impeded by dust
extinction
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Contribution to the signal as function of z
Ando et al., 2003
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Supernovae Relic ne
SRN Rate (between 9.8 and 30 MeV) 28 55 / (10
a) Background 8 / (10 a) Spectral shape
analysis possible Redshift z 2 Separation LL
vs. TBP possible (90 cl)
M. Wurm Diploma thesis
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Supernovae Relic ne
Threshold at Kamioka 12 MeV (for water
Cherenkov detectors) Redshift z 1 Between 21
and 37 lower rate (compared to Pyhäsalmi) Best
locations Hawaii, Australia
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Supernova Neutrinos
Assumption Supernova II with 8 solar masses at
10 kpc distance
ne flux and spectrum
ne flux and spectrum
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Supernova Neutrinos
Total neutrino flux
Total energy spectrum
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Supernova and neutrino properties

• Wiggles in the ne spectrum observable
• if spectra or fluxes of SN neutrino flavors
  differ
• if neutrinos pass the Earth before entering LENA

yes
no
Smirnov, Dighe, Raffelt...
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Solar Neutrinos
LENA Fiducial Volume for solar n 18 x 103 m3

• High statistic ( 5.4 x 103 / day ) 7Be n
  e -gt n e
• test of small flux fluctuations in time
• CNO and pep neutrinos ( 3 x 102 / day )
• solar neutrino luminosity
• contribution of CNO cycle to solar energy
  release
• Charged current ne (13C,13N) e- reaction (
  103 / year )
• spectroscopy of 8B-n at energies below 5 MeV
• (A. Ianni et al., hep-ph/0506171)

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Test of MSW effect
7Be pep CNO
MSW effect
8B
8B via 13C
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Geo Neutrinos

• Detection via inverse beta decay
• measurement of radiogenic contribution to
  terrestrial heat ( 40 TW)
• test of the Bulk Silicate Earth model
• test of unorthodox models of Earths core (is
  there a breeder reactor ?)

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Rate of Geo-neutrinos in LENA
LENA _at_ Pyhäsalmi 1.5 x 103 events / year
TNU (1 capture in 1032 protons per year) Scaling
KamLAND result to LENA between 3 x 102 and 3 x
103 events / year
G. Fiorentini et al., hep-ph/0401085
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Distinction potential between U- and Th-series
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Geo-neutrinos and LENA
Displacement n,e for directionality ?
e.g. 21 TW core model Indication (1 s) after a
couple of years
zenith angle distribution in LENA
K. Hochmuth Diploma thesis
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LENA and Proton Decay
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Event structure in LENA
K-gtm n
Background suppression 5 x10(-5) Acceptance
65
K
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Background suppression in LENA
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T. Marrodan Undagoitia Diploma thesis
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Actual SK limit 2.3 x 1033 y after 10 years
40 events (lt 1 background event) 90cl
limit 4 x 1034 years
T. Marrodan et al., Phys. Rev. D 72, 075014 (2005)
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LENA and long baseline accelerator experiments

• Search for Q13
• e.g. at a Betabeam (nm appearance experiment)
• Separation between muon- and electron like events
  ?
• Two methods under investigation
• pulse shape discrimination (works fine for HE)
• muon decay (delayed coincidence)
• problem pion production E gt 400 MeV and
  successive decay into muon

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Muon
Electron
Muon (800 MeV) Tau 8 ns (risetime 15 - 85)
Electron (800 MeV) Tau 4 ns
Time (ns)
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Conclusion

• LENA a low energy neutrino observatory
• Impact on astro- ,particle-, geophysics
• Complementary to Neutrino Telescopes
• Feasibility studies very promising