LENS—Overview R. S. Raghavan Virginia Tech LONU-LENS Mini Workshop Oct 14, 2006

1. LENS—Overview R. S. Raghavan Virginia Tech LONU-LENS Mini Workshop Oct 14, 2006

2. Neutrino beams from SUN • Very Low Energy • Pure Favor (e) • Largest Fluxes • Longest Base Line • Largest Intervening Mass • Highest Magnetic Fields • Unique Machine for Exploration of • Neutrino Phenomenology in • Vacuum, Matter & Magnetic Fields • STATUS: • From High Energy Nus ( 8B & Atmos) • Non-zero Neutrino Mass • Neutrino Flavor Conversion • NEXT…Door open to Explore • New Physics & Astrophysics Solar Neutrinos-Past & Future SSM Prediction Directly measured so far Directly measured The New Frontier • New Quest: Discoveries beyond Oscillations- • New Paradigm: Precision Data, solar model independence • New Frontier: < 2 MeV • Central Objectives of LENS

3. Tagged ν –capture reaction in Indium LENS is the only developed CC real time detector for solar neutrinos signal delay Tag cascade • Unique: • Specifies ν Energy • Eν= Ee + Q • Complete LE nu spectrum • Lowest Q known 114 keV • access to 95.5% pp nu’s • Target isotopic abundance ~96% • Powerful delayed coinc. Tag • Can suppress bgd =1011 x signal • Downside: • Bgd from 115In radioactivity to • ( pp nu’s only) rate= 1011 x signal • Tools: • Time & Space coinc. Granularity (106suppression) • Energy Resolution • In betas <500 keV; ∑Tag = 613 keV • 3. Other analysis cuts

4. Indium Solar Neutrino Detection—R&D History Hi Granularity(~109) --Lo precision pp (3σ) Tagged pp reaction in Indium RSR-PRL 1976 Bell Labs (rsr, Pfeiffer, Mills) 1976-79 pp InLS/Plastic Sandwich Indium β-spectrum Bell Labs-MIT (rsr, Deutsch) 1979-84 pp Plastic/Quartz Fiber Scint Oxford (Booth) 1978-90 pp Indium Tunnel Diodes CEA Saclay (Cribier, Spiro) 1979-81 pp Hybrid TPC/Plastic Penn-Coll de France-KEK-BL-TUM 1987-89 Be InLS (KEK- Suzuki, Inoue) Borexino 1989 - Be ν-e-scattering –no tag Brute force reduction of bgd via invention of new ultrapurity chemistry New tgged pp capture reactions—non radioactive targets –RSR-PRL 1997 LENS R&D LNGS-EU-Russia-USA 1999-01 pp Yb, Gd, Se –YbLS Lo Granularity (105) —Hi Precision pp (3%) (SNO result ! ) RSR-hep-ph/010605 LENS R&D LNGS-- 2001-03 pp In InLS LENS-Sol/CAL 2004- Nu Lum InLS (LENS-Sol) Plastic Sandwich (LENS-Cal)

5. Major Progress from LENS LNGS LENS Sol • < Towards Hi Precision pp > • Hi Quality InLS Developed • Background Analysis Insights • New Detector Design Invented Transparency of InLS 8.6 m after 8 months

6. Expected Result from LENS • Background precisely and concurrently measured • Well resolved low energy solar nu spectrum – •  pp, 7Be, pep, CNO with 99+% of solar nu flux • Solar luminosity in nu’s • pp spectral shape accessible for first time

7. pp Spectral Shape New Science Goal • Directly Probe Temperature Profile of Energy Production in the Sun by experimentally measuring the Gamov Energy Shift in • pp Fusion (not observed in laboratory so far) • Experiments focused so far on fluxes, not (absolute) energiesof solar nu’s ----not possible via electron scattering or radiochemistry •  need energy specific CC detection technology -LENS • Energies of neutrinos from Fusion reactions are usually taken from exothermal • energy release (Q value i.e. difference of initial and final masses) e.g. • p + p  d + e+ + νe (420 keV max); p + e- + p  d + νe(1442 keV) • This does not include the kinetic (Gamov) energy needed to initiate pp fusion • Gamov Energy E0 (T) is temperature dependent • E (T) is added to the pp and pep energy spectra weighted by the fraction of the flux produced at that temperature---E is typically ~5 keV • i.e. pp425 keV and pep1447 keV • Can one observe the Gamov shift by measuring pp and pep energies? If so---we can directly measure the • temperature profile of energy production by pp fusion

8. (Z=50) Sn aMaximum energy; bShift of mean energy of signal spectrum in the detector, in the case of pp in the energy range <110-340> keV ; cShift of maximum energy in sun. The E includes likely systematic errors (see text) P lab (q,Qs) ~ q2 p W F(Z,W,Qs) (Z= -1 ) Sun: Target: Fit measured spectrum to Psun leaving q max free Find δE from repeated trials; compare to predicted ΔE σ = 1.63 keV Grieb/RSR hep-ph/0609030

9. Science from Neutrino Flux Data • Basic Dichotomy in Solar neutrino Research: • Measured Fluxes vs Unknown Original Fluxes in sun • All science interpretations need ORIGINAL fluxes • Usual Practice: Appeal to predictions of Standard Solar Model • How to make inferences completely free of models? • First Breakthrough: Made by SNO in the case of 8B flux • Single solar source 8B • SNO, SK • Measured 8BNC “flavor-blind” fluxoriginal flux in sun • SK CC+NC spectrum –flavor survival independent of energy • Kamland data with ANTINEUTRINOS • LMA matter conversion at 8B neutrino energies (~10 MeV) • Major Questions: • Conclusion assumes CPT invariance. Is This Correct ?–First opportunity to • Test this for NEUTRINOS • 2) LMA if true, predicts different type of conversion at LOW ENERGIES • Verify this: Beyond LMA Discovery ! • Imperative to test 1) and 2):

10. Major Questions: 1) CPT invariance for NEUTRINOS 2) LMA prediction of different type of conversion at LOW ENERGIES 3) Deviations from LMA predictions Discovery Imperative tests HOW to attack the problem on a model independent basis?  Model Independent Fluxes at LOW ENERGIES ? Basic Need: Fluxes of single sources Well identified and resolved Spectroscopic data Removal of precisely measuredbackground  Requires CC based Low Energy DetectionDeveloped only in LENS Bgd Est. Bgd measured Scattering Spectrum (CLEAN) Absorption Spectrum (LENS)

11. Solar Luminosity from Low Energy Neutrino Flux data from LENS • Use Best Known Neutrino Model (e.g. LMA) to reverse calculate original • Fluxes from measured fluxes of INDIVIDUAL sources: • pp, Be, pep & CNO, constitute 99+% of solar neutrino flux • Calculate Energy by weighting fluxes with coefficients of energy released • in each solar reaction (Bahcall, Phys. Rev C 65 (2002), 025801) • Solar Luminosity in Neutrinos L(ν inferred) From Solar Constant • Solar Luminosity in Photons L(hν) Energy Match from two probes: L(ν inferred) / L(hν) = 1.00 This tests if the neutrino model used is CORRECT • No SSM used; Inference only via measured quantities Present Status after 40 years of Solar nu research: L(ν inferred) / L(hν) = 1.4 (+0.2-0.3; 1 σ)( +0.7-0.6; 3σ) Bahcall & C. Penya-Garay, JHEP 4, 0311 (2003); R.G.H. Robertson, Prog. Part. Nucl. Phys. 57, 90 (2006) suggests Lν /L (hν) ~1.12±0.2. • Wide Room For Surprises • Neutrinos notorious for Surprises !

12. New Global Analysis using: • Data from LENS: • Measured v Fluxes of pp, Be, pep, CNO • Solar Luminosity in Neutrinos • Temperature of sun via Gamow shift ; • Data from SNO • 8B flux (CC and NC); • SK data on spectrum • Match to Measured Photon Luminosity by varying νparameters • (use the temperature shift to test SSM prediction of dependence of • of pp flux on T ( (1-0.08(T/TSSM)-1.1) J. N. Bahcall & A. Ulmer, Phys. Rev. D53, 4202 (1996). • This global analysis ASSUMES: • 1) Nuclear Reactions SOLE source of Sun’s Energy • 2) Quasi hydrostatic Equilibrium •  Neutrino Luminosity Now = Photon Luminosity Now from • Energy created 105 years ago

13. With Precise Model Independent pp, Be,pep fluxes: Energy Dependence of Survival Probabilities: Test LMA, NSI, MVA, Measure θ12 Precisely e) Be/pp ~5% pep/pp~9% LMA Mass Var. Nu’s Precision θ12 Sterile Nu NSI Be/pp ~18% pep/pp~40%

14. Conclusion LENS TECHNOLOGY INTRODUCES Recipe for Discovery in Particle Physics --CPT, NSI, MVN, Θ12 , Θ13 from absolute energy Astrophysics of Sun –CNO,Hidden sources of energy, Past Sun vs Present Sun, Temp of pp fusion (test SSM) A new comprehensive approach for model independence : Measuring the Solar Luminosity in Neutrinos and comparing it directly with the Photon Luminosity

15. LENS-Sol / LENS-Cal Collaboration (Russia-US: 2004-) Russia INR (Moscow): I. Barabanov, L. Bezrukov, V. Gurentsov, V. Kornoukhov, E. Yanovich IPC (Moscow): N. Danilov, G. Kostikova, Y. Krylov INR (Troitsk) I: J. Abdurashitov, V. Gavrin. et al. II: V. Betukhov, A. Kopylov, I. Oriachov, E.Solomontin U. S.: BNL: R. L. Hahn, M. Yeh UNC: A. Champagne ORNL: J. Blackmon, C. Rasco, Qinlin Zeng, A. Galindo-Uribarri Princeton U. : J. Benziger SCSU: Z. Chang Virginia Tech: C. Grieb, J. Link, M. Pitt, R.S. Raghavan, R. B. Vogelaar,