LENS, MINILENS STATUS

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LENS, MINILENS STATUS R. S. Raghavan Virginia
Tech ForThe LENS Collaboration NSF-DUSEL Town
Meeting Washington DC Nov 3 2007
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LENSLow Energy Neutrino Spectroscopy
LENS is the only CC detector developed to date
for low energy solar neutrinos
RD Funded now by NSF Placed in MUST FUND
Category by two Review Panels
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LENS Detection Scheme

• Unique
• Specifies ? Energy
• E? Ee Q
• Complete LE nu spectrum
• Lowest Q known? 114 keV
• ?access to 95.5 pp nus
• Target isotopic abundance 96
• Powerful delayed coinc. Tag
• Can suppress bgd 1011 x signal
• Downside
• Bgd from 115In radioactivity to
• ( pp nus only)? rate 1011 x signal
• Tools
• Time Space coinc.? Granularity (106suppression)
• Energy Resolution
• In betas lt500 keV ?Tag 613 keV
• 3. Other analysis cuts

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Expected Result Low Energy Solar ?-Spectrum

• LENS-Sol Signal
• SSM(low CNO) LMA
• x
• Detection Efficiency e
• pp e 64
• 7Be e 85
• pep e 90
• Rate pp 40 /y /t In
• 2000 pp ev. / 5y? 2.5
• Design Goal S/N 3

Tag Delayed coincidence Time Spectrum
Signal area
Bgd
S/N 1
S/N 3
Coincidence delay time µs
Fitted Solar Nu Spectrum (SignalBgd) /5 yr/10 t
In
pp
S/N3
SIMULATION
7Be
Indium Bgd
CNO
pep
Access to pp spectral Shape for the first time
7Be
Signal electron energy ( E? Q) (MeV)
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• Science from LENSHi precision low energy
• Nu fluxes (pp? 3-4)
• Neutrino Physics Energy dependence of Pee
• ? Oscillation Phenomenology
• 2. Solar Luminosity vs Photon LluminosityAstrophy
  sics/Neutrino physics
• 3. Gamow Energy of pp fusionEnergy production
• in sun
• 4. Physics beyond Std modelSterile Neutrinos
  from
• LENSSource
• 5. Solar model independent Fluxes CCNC
• (LENS Borexino)

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Neutrino Phenomenology from LENS
In the first 2 years (no calibration with
?-source needed)

• Test of MSW LMA physics - no specific physics
  proof yet !
• Pee(pp)0.6 (vac. osc.) Pee(8B)0.35 (matter
  osc.), as predicted?
• Non-standard Fundamental Interactions?
• Strong deviations from the LMA profile of Pee(E)
  ?
• Mass Varying Neutrinos?
• (see above)
• CPT Invariance of Neutrinos?
• so far LMA only from Kamland , is this true
• also for neutrinos ?
• RSFP/ Nu magnetic moments
• Time Variation of pp and 7Be signals? (No Var.
  of 8B nus !)
• 
  (Chauhan et al JHEP 2005)

Low Energy Neutrinos Only way to answer these
questions !
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Solar Luminosity Neutrino vs. photon
Energy Balance
Measured neutrino fluxes at earth oscillation
physics nuclear reaction rates energy release
in the sun
Solar luminosity as measured by photon flux

• Will be met under these conditions
• Fusion reactions are the sole source of energy
  production in the sun
• The sun is in a quasi-steady state (change in
  40,000 years is negligible)
• The neutrino oscillation model is correct no
  other physics involved
• From a single detector
• Test of astrophysics, solar model
• Test of neutrino physics (LMA-MSW at low E, NSI,
  mass-varying ns, Q13, )

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Neutrino inferred Luminosity of the Sun -
Experimental Status
Main contributions
pp 0.91 7Be 0.074 (CNO 0.014)
8B 0.00009

• Measured neutrino fluxes at the earth
• 8B (SK, SNO) known very well
• 7Be 8B (Cl) sensitive mostly to 8B
• pp 7Be 8B (Ga)
• 7Be (Borexino, Kamland in the future)
• in principle can deduce pp-? flux
• Problem disentangling fluxes from individual
  neutrino sources

Experimental status No useful constraint!
R.G.H.Robertson, Prog. Part. Nucl. Phys. 57, 90
(2006)
J.N.Bahcall and C.Peña-Garay, JHEP 0311, 4 (2003)
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Solar Nus Contd Model independent astro and nu
physics Borexino LENS

• Borexino Signal
• (CC NC) ?e ?x
• LENS Signal
• (CC) ) ?e only
• ? Important New Advantages
• Be flux
• ?provides means of eliminating
• need for measuring the Indium
• nu capture cross section
• 2) Eventually pep, CNO also
• ? 336 independent data
• ? global analysis
• ? model independent fluxes, solar
• mixing angle.

7Be
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New Technology of LENS Developed in last three
years
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• Technology and Bgd Control
• lt Towards Hi Precision pp neutrino flux gt
• Hi Quality InLS
• New Detector Design
• Background Analysis Insights? -115 In decay
  bgd
• suppressed ?S/N 3 for first time

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Indium ?--Background Structure Space / Time
coincidence
Signal
Signal Signature Prompt e- ( )followed by low
energy (e-/?) ( ) and Compton-scattered ? (
) -gttime/space coincidence -gt tag fixed energy
613keV -gtcompton scattered shower
Background Random time and space
coincidence between two ?-decays ( ) Extended
shower ( ) can be created by a) 498 keV ? from
decay to excited state b) Bremsstrahlungs ?-rays
created by ? c) Random coincidence (10 ns) of
more ?-decays Or any combination of a), b) and
c).
Bgd
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Indium ?--Background Discrimination

• Background rejection steps for pp detection
  (other neutrinos detected free of Indium
  background)
• Time/space coincidence in the same cell required
• for trigger
• B. Tag requires at least three hits
• C. Narrow energy cut
• D. A tag topology multi-? vs. Compton shower
• Classification of events according to hit
  multiplicity
• Cut parameters optimized for each event class
• improved efficiency

Reduction by 3.107 through time/space coincidence
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Indium Liquid Scintillator Status
Milestones unprecedented in metal LS
technology LS technique relevant to many other
applications
1. Indium concentration 8wt (higher may
be viable) 2. Scintillation signal efficiency
(working value) 8000 h?/MeV 3. Transparency at
430 nm L(1/e) (working value) 8m 4.
Chemical and Optical Stability at least 1
year 5. InLS Chemistry Robust New LAB based
InLS
Basic Bell Labs Patent, Chandross, Raghavan
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InLS progress

• New LAB based InLS
• LABLinear Alkylbenzene (light yield 85 of PC
• Largely similar to PC experience but v high
• Flash point gt100C, very cheap
• Indium loading 8
• Light yield 85 of InLS(PC)
• L 7m BUT higher sensitivity to
• Air exposure Need further work to fix
• Current focus closed system automatic
• synthesis via continuous extractor
• systems) ----bench-5L scale
• and MiniLENS scale100L

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New Detector Technology hi event position
localization The Scintillation Lattice Chamber
Test of double foil mirror in liq. _at_2bar
Light channeling in 3-d totally Internally
reflecting cubic Lattice GEANT4 sim. of concept.
Demonstration Acrylic Model

• 3D Digital Localizability of Hit within one cube
• ? 75mm precision vs. 600 mm (2s) by TOF in
  longitudinal modules
• ? x8 less vertex vol. ? x8 less random coinc. ?
  Big effect on Background
• ? Hit localizability independent of event energy

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Lattice Structure
Single Foil
Double Foil
Solid teflon segmentation
Double-layer (air-gap) lattice
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• Can you build it with liquids?
• Film and structure?
• Various single films (Fluorinated)
• Double films with various fluids
• Test small scale.
• Ethylene Glycol
• Teflon FEP with Acrylic film for support

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RD In Progress --Issues

• Single foils vs- sealed double layers
• Multi-layers?
• Antireflective coatings
• Chemical compatibility
• Optical attenuation
• Structural integrity
• Cost?

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MINILENS
Final Test detector for LENS

• Goals for MINILENS (250 L Scint
• 25 kg In)
• Test detector technology
• ? Medium Scale InLS production
• ? Design and construction
• Test background suppression of In
• radiations by 10-11
• ? Expect 5 kHz In ?-decay singles
• rate adequate to test trigger
• design, DAQ, and background
• suppression schemes
• Demonstrate In solar signal detection in the
  presence of high background (via proxy)
• Direct blue print for full scale LENS

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Proxy pp-? events in MINILENS

• Proxy pp nu events in MINILENS from cosmogenic
• 115In(p,n)115Sn isomers
• Pretagged via ?, p tracks
• Post tagged via n and
• 230 ? s delay
• ? Gold plated 100 keV
• events (proxy pp),
• Tagged by same cascade
• as In-? events
• ? Demonstrate In-? Signal
• detection even in
• MINILENS

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MINILENS Progress

• Electronics PMTs procured
• 150 Photonis PMTs High PHR, low noise,
  10-stage, 76 mm (3") round tube
• Quad Linear/ Logic unitde z9WFRC, TDC, FI/F0
• DAQ SupportHV supplies, crate controllers,
• 32 Channel Photomultiplier Preamplifier, NIM
  Model 779
• 5 FADC Summer 2007
• Work Started at UNC-NCSU, LSU --) in electronics
  design
• Work initiaated at IUCF on shielding/vetos/enginee
  ring ?
• Complete building Kimballton Lab
• Infrastructure installation
• Scintillator fabrication (VT with BNL
  Cooperation)
• Lattice design complete Mark I design
• and materials search (VT)

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The Kimballton Underground Facility Depth 1400
mwe
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MiniLENS, LENS Time linesCrude Costs MINILENS
Cost 2M Time Line Final Design ,
Infrastructure in Kimballton

2008-09 Installation and Data Taking
2010 LENS Cost
25 Design and Engineering (with input from
MINILENS
2009-11 Construction

2012-14 Data Taking
2015

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LENS Collaboration (Russia-US 2007)
Russia INR (Moscow) I. Barabanov, L.
Bezrukov, V. Gurentsov, V. Kornoukhov, E.
Yanovich U. S. BNL R. L.
Hahn, M. Yeh Indiana
U. Rex Tayloe U. North
Carolina A. Champagne
North Carolina State Albert Young. H.
Back Louisiana State J. Blackmon,
C. Rascoe, Q. Zeng
ORNL A.
Galinde-Urribari
Princeton U. J. Benziger
South Carolina State Z. Chang,
Virginia Tech M. Pitt, R.S.
Raghavan,
D. Rountree, R.B.
Vogelaar