LENS Low Energy Neutrino Spectroscopy

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LENS - Low Energy Neutrino Spectroscopy

• Thomas Bowles
• Los Alamos National Laboratory /
• University of Washington
• TAUP 03
• University of Washington
• September 6, 2003

Nuclear Physics
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LENS Collaboration

• College de France, Paris
• A. de Belefon, T. Beau, H. de Kerret, D. Kryn, M.
  Obolensky, D. Vignaud
• Dapnia, CEA/Saclay
• J. Bouchez, P. Bourgeois, C. Cavata, R. Chipaux,
  M. Cribier, G. Fioni, T.Lassere,
• J. Mallet, J.P. Meyer, C. Veyssiere, H. Zaccone
• Max Planck Inst. fur Kernphysik, Heidelberg
• C. Buck, W. Hampel, F. Hartmann, J. Kiko, D.
  Motta,
• T. Kirsten, S. Schoenert, H.Simgen
• LNGS, Gran Sasso
• M. Balata, V. Berezinsky, A. Bettini, C.
  Cattadori, N. Ferrari
• RCNP, Univ. Osaka M. Fujiwara
• Institute of Nuclear Research RAS
• I.R. Barabanov, V.I. Beresnev, L.B. Bezrukov,
  V.I. Gurentsov, V.N. Kornoukhov,
• N.P. Nesterova, O.G. Ryazhskaya, E.A. Yanovitch,
  G. T. Zatsepin
• Inst. of Physical Chemistry RAS
• N. A. Danilov, V. M. Gelis , G. V. Korpusov, G.
  V. Kostikova, Yu. S. Krylov
• Inst. of Chemical Technology V. V. Yakshin
• Inst. for Theoretical Exptl. Physics B.
  Kochurov, V. Konev
• Bell Laboratories R. S. Raghavan

Nuclear Physics
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LENS Physics Goals

• p-p flux is the standard candle for solar
  neutrinos
• Measure the ne flux of p-p and 7Be to a few
  accuracy
• Measure the ne flux of CNO to 10
• Search for sterile neutrino component at few
  level
• (requires a measurement of p-p NC)
• Search for CPT violation at few level
• (combined with KamLAND results)
• Push towards improved accuracy on q12
• (requires 1-2 accuracy)

• Requires detector with
• low threshold (100 keV)
• p-p count rates (1000 cts/yr)
• high S/B ( 10/1)
• calibration of reaction cross section to few
  accuracy
• (multi-MCi 51Cr source calibration)

Nuclear Physics
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LENS - CC Reaction Signature
115In count rate 95 p-p events/yr/ton
Signature is inverse b correlated spatially and
temporally with (e/g)2 and g3
115In b decay rate is 250 kHz/ton!
Nuclear Physics
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LENS Detector Design
Nuclear Physics
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LENS RD Issues
Nuclear Physics
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Light Yield as a function of In loading
New Indium-carbhydroxide LS formulation (August
02 LNGS-INR)
Optical Properties In-LS 4 g/l BPO 15 mg /l
bisMSB
LY 100 is for pure Pseudocumene 5 g/l BPO
INFN / INR
Gran Sasso National Laboratory
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Comparison of pure PC and InLS
InLS (BPO 5 g/l) In 85 g/l PC (BPO
5g/l) LY 67 _at_ In 80 g/l
Pure PC (green) and InLS (red) (new
LNGS-INR formulation)
INFN / INR
Gran Sasso National Laboratory
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In Acac scintillator (45g/l Indium)
Performances in 5cm x 5cm x 100cm prototype
cell 137Cs source at center
Compton back-scattering-peak (deposited energy
477keV)

• En. Res. (1?) 11.6
• Space Res. (1?) 7cm
• Light at center 200 pe/MeV
• Effective Att. Length 128cm

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Status - Scintillator RD
Nuclear Physics
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LENS Low-Level Background Facility at Gran Sasso
Nuclear Physics
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First background results from LENS prototype
detector at LLBF
LENS-LLBF Inner Array
Integral bkg rate 2.1x10-3 c/s/kg (single hits,
50 keV threshold)
14C/12C 10-17 in PXE (measured in 2 liter cell!)
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Status - Detector RD
Nuclear Physics
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LENS Future Plans

• Early 2004
• Complete scintillator and detector RD
• Complete background measurements in LLBF
• Finalize design for full-scale detector

• Appears likely that In-LENS will be technically
  feasible
• Potentially measure p-p to 3-4, 7Be to
  4-5, CNO to 10

But the price you pay is Achieving S/B gt 3
requires e (p-p) 25) In loading likely to
be limited to 4-5 Total scintillator volume
driven into kiloton range Fine segmentation
required leads to gt 45,000 PMTs Total cost
is likely to be 70M

• LENS collaboration to decide on proposal in
  spring 2004

Nuclear Physics