LENA

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LENA
LENA Delta

• Low Energy Neutrino Astrophysics

L. Oberauer, F. von Feilitzsch, C. Grieb, K.
Hochmuth, C. Lendvai, T. Marrodan, L.
Niedermeier, W. Potzel, M. Wurm Technische
Universität München www.e15.physik.tu-muenchen.de
/research/lena.htlm
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Groups interested in LENA

• TU Munich, Germany
• Univ. Hamburg, Germany (C. Hagner)
• CUPP, Finland (J. Peltoniemi)
• Univ. Jyväskylä, Finland (J. Aysto)
• INR, Russia (L. Bezrukov)
• Similar initiative
• HSD (Hyper-Scintillation-Detector) Kimballton
  mine, Virginia, USA

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LENA
Proposal A large (50 kt) liquid
scintillator underground detector for

• Baryon number violation
  Proton decay
• Gravitational collapse
  SN n detection
• Star formation in the early universe
  Relic SN n
• Solar thermonuclear fusion processes
  CNO, pep, 7Be
• Geophysical models
  U, Th - n
• Neutrino properties Long
  baseline - n

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LENA Detector and scintillating liquid
100m
30m
Muon veto
12000 Pms (50cm)

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

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PXE as scintillating solvent

• PXE tests _at_ Counting Test Facility from BOREXINO
  at Gran Sasso (physics/0408032)
• 372 pe / MeV _at_ 20 coverage
• lattenuation 4 m _at_ 430 nm
• lattenuation 12 m after purification
• (alumina-column, S. Schönert MPIK Hd for LENS)
• gt 120 pe / MeV in LENA (central events)
• gt low energy threshold (sub-MeV)
• gt good resolution in energy and position
  reconstruction

CTF
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Program for investigations of PXE / dodecane
mixtures

• C, Buck et al., MPIK Heidelberg
• (Double-Chooz)
• M. Wurm, K. Hochmuth, TUM
• improve compability with detector materials
• improve further transparency?
• increase free H number (by 30)

90 light yield with 40 PXE and 60 dodecane
M. Wurm
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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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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
• standard technology (PM-encapsulation,
  electronics etc.)
• LENA is feasible in Pyhäsalmi !

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Pylos (Nestor Institute) in Greece
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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
• The Kaon and the K-decay particles are visible
  in LENA
• Better energy solution further reduces
  background

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K-gtm n 63.4
K-gtpp0 21.1
Teresa Marrodan
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bg-events
P-decay
bg-events

• Event structure p -gt K n plus K decay
  (T1/2 12.8 ns)
• 3-fold delayed coincidence from m - decay

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Potential of LENA for p -gt Kn SuperK current
limit t 1.6 x 1033 y 27 events in 10 years
in LENA (0.7 bg events) No signal t gt 3 x
1034 y
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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
ne
Water Cherenkov
Scintillator good resolution
Modulations in the energy spectrum due to matter
effects in the Earth
Dighe, Smirnov, Keil, Raffelt
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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

Dependence on hierarchy and Q13
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Survival probability
Mixing angle between ne and n2 in Earth matter
Mass difference squared in Earth matter
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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 star formation in the early
  universe

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Reactor SK
No background for LENA !
Reactor bg LENA !
SRN
6 counts/y
Atmospheric neutrinos
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Low energy atmospheric neutrinos and LENA

• LENA can measure the low energy part of
  atmospheric neutrinos, esp. ne
• 30 MeV - 200 MeV ne
• Losc 103 km to 7 x 103 km
• (Dm2 solar neutrinos!)
• ne lt-gt nm atmospheric oscillations, but
  based on Dm2solar
• observable ?
• ...difficult (low statistics) needs further
  investigations

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• Thermal nuclear fusion and LENA
• high statistic 7Be-solar n detection (104 d-1)
• test of even small flux variations
• look for coincidences with helioseismological
  data !
• CNO and pep-n (300 d-1)
• solar neutrino luminosity
• precise determination of solar nuclear fusion
  processes

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Long baseline n - oscillations and LENA ?

• To be investigated in detail
• n spectrum (off-axis)
• e, m - separation potential
• potential in Q13

!
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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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• Geo - neutrinos and LENA
• what is the source of the terrestrial heat flow
  ?
• what is the contribution of natural
  radioactivity ?
• how much of U, Th is in the mantle ?
• is there a natural reactor at the Earths
  center?

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• Angular distribution information
• reconstruct vertices of prompt and delayed
  events
• resolution 30o (MonteCarlo)

maximum model
Core enhanced
minimal model
K. Hochmuth
Q (rad)
Events per year
0 lt ? lt 60 60 lt ? total
ref 618 25 822 29 1440 38
min 453 21 653 27 1106 33
max 1255 35 1365 37 2620 51
core 950 31 858 29 1807 43
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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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Signal in LENA
m
m
K
K
time (nsec)
P decay into K and n
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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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Sensitivity of LENA ?

• 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. proton decay,
  astrophysics, neutrino physics, geophysics
• feasibility studies very promising (CUPP,
  Pyhäsalmi)
• costs ca. 100 - 200 M