LENS: Measuring the Neutrino Luminosity of the Sun R. S. Raghavan Virginia Tech Henderson Capstone DUSEL Workshop Stony Brook University May 5, 2006

Russia: INR (Moscow):I. Barabanov, L. Bezrukov, V. Gurentsov, V. Kornoukhov, E. Yanovich; INR (Troitsk):V. Gavrin et al., A. Kopylov et al.; U. S.: BNL:A.Garnov, R. L. Hahn, M. Yeh; U. N. Carolina:A. Champagne; ORNL:J. Blackmon, C. Rasco, A. Galindo-Uribarri; Princeton U. :J. Benziger; Virginia Tech:Z. Chang, C. Grieb, M. Pitt, R.S. Raghavan, R.B. Vogelaar; LENS-Sol / LENS-Cal Collaboration (Russia-US: 2004-)

Best part --Free of Charge For NEUTRINO PHYSICS: WELL DEFINED HIGHEST FLUX (pp) FLAVOR PURE - ν e only LONGEST BASELINE LARGEST MASS OF HIGH DENSITY LOWEST ENERGIES (keV to MeV) LOW ENERGY SPECTRUM - ENERGY DEP. EFFECTS Best tools for investigating neutrino flavor phenomena in Vacuum and in Matter For ASTROPHYSICS Best tool for unprecedented look at how a real Star works - in the past, present and future “Very Super” Neutrino Beam from the Sun

Solar Neutrinos Standard Solar Model Missing e (Cl, Ga, SK, SNO) Flavor mixing happens (SNO) Leads naturally to New Era of precision measurements and tests What we know:

Critical Test if All solar energy is nuclear:  Neutrino luminosity = Photon Luminosity Experimental status after 40 y of solar nu’s– No useful constraint for critical test of Neutrino physics or solar astrophysics! Solar Luminosity: Neutrino vs. Photon

Three main contributions:pp Be B Solar Luminosity: Neutrino vs. Photon Accent of future test of nu luminosity on Individual fluxes of LOW ENERGY Neutrinos especially pp neutrinos Direct spectroscopy PRECISION Fluxes No direct pp neutrinos so far New Experiments needed Measuring Neutrino Luminosity  Measuring pp, and other low energy neutrinos

LENS-Sol:  Measure the low energy solar electron - spectrum  (pp, 7 Be, pep, CNO)  ± ~3% pp- flux in 5 years of data  Experimental tool: Tagged CC Neutrino Capture in Indium LENS-Cal:  Measure precise B(GT) of 115 In CC reaction using MCi 51 Cr neutrino source at BAKSAN  Tagged -capture to specific level of 115 Sn  Note: B(GT) = 0.17 measured via (p,n) reactions LENS-Indium: SCIENCE GOAL Precision Measurement of the Neutrino Luminosity of the Sun

Test of MSW LMA physics - no specific physics proof yet ! P ee (pp)=0.6 (vac. osc.) P ee ( 8 B)=0.35 (matter osc.), as predicted? Non-standard Fundamental Interactions? Strong deviations from the LMA profile of P ee (E) ? Mass Varying Neutrinos? (see above) CPT Invariance of Neutrinos? so far LMA only from Kamland, is this true also for ? RSFP/ Nu magnetic moments Time Variation of pp and 7 Be signals ? (No Var. of 8 B nus !) (Chauhan et al JHEP 2005) NEW SCIENCE - Discovery Potential of LENS APS Nu Study 2004  Low Energy Solar Nu Spectrum: one of 3 Priorities In the first 2 years (no calibration with -source needed ): Low Energy Neutrinos: Only way to answer these questions !

New Science from Relative Fluxes MSW-LMA Profile Non-standard interactions Mass-varying neutrinos Deviations from standard survival probability in various new scenarios

pp, 7 Be -fluxes at earth ±3%  Measured Neutrino Luminosity ~4%  Ultimate test of the Sun And the Neutrino  Astrophysics: L > L h Is the sun getting hotter? L < L h Cooling or a sub-dominant non-nuclear source of energy in the sun?  Test also neutrino physics  because the L ν derivation needs best  known nu parameters  Precision values of θ 12, θ 13 (from cos 4 θ 13 dependence of all fluxes)  Sterile Neutrinos? ( especially with CC from LENS and NC from  electron scattering) NEW SCIENCE - Discovery Potential of LENS In 5 years (with - source calibration):

Tag: Delayed emission of (e/  )+  Threshold: 114 keV  pp- ’s 115 In abundance: ~ 96% Background Challenge: Indium-target is radioactive! (  = 6x10 14 y) 115 In β-spectrum overlaps pp- signal Basic background discriminator: Time/space coincidence tag Tag energy: E - tag = E βmax +116 keV 7 Be, CNO & LENS-Cal signals not affected by Indium-Bgd! LENS-Indium: Foundations CC -capture in 115 In to excited isomeric level in 115 Sn

LENS-Sol Signal = SSM(low CNO) + LMA x Detection Efficiency  pp:  = 64% 7 Be:  = 85% pep:  = 90%  Rate: pp 40 /y /t In  2000 pp ev. / 5y  ±2.5%  Design Goal: S/N ≥ 3 Expected Result: Low Energy Solar -Spectrum Access to pp spectral Shape for the first time Signal electron energy (= E ν – Q) (MeV) Coincidence delay time μs Tag Delayed coincidence Time Spectrum Signal area Bgd S/N = 1 S/N = 3 Fitted Solar Nu Spectrum (Signal+Bgd) /5 yr/10 t In Indium Bgd S/N=3 pp 7 Be pep CNO 7 Be*

In-LENS: Studied Worldwide Since 1976! Dramatic Progress in 2005 ( MPIK Talk at DPG 03/2004) Cubic Lattice Non-hybrid (InLS only) InLS: 8% In, L(1/e)>10m, 900 pe/MeV Mass InLS : 125t to 190t In: 10t-15t for 1970 pp ’s /5y PMTs: 13,300 (3”) - 6,500 ( 5”) pp- Detection Efficiency: 64-45% S/N ~3 (ALL Indium decay modes) Status Fall 2003  Status Fall 2005 In Liq. Scint. New Design Bgd Structure New Analysis Strategy Longit. modules + hybrid (InLS + LS) InLS: 5% In, L(1/e)=1.5m, 230 pe/MeV Total mass LS: 6000 t In: 30t for 1900 pp ’s /5y PMTs: ~200,000 pp- Detection Efficiency: ~20% S/N~1 (single decay BS only) ~1/ 25 (All In decay modes)

1. Indium concentration ~8%wt (higher may be viable) 2. Scintillation signal efficiency (working value): 9000 h /MeV 3. Transparency at 430 nm: L(1/e) (working value): 10m 4. Chemical and Optical Stabililty: at least 2 years 5. InLS Chemistry - Robust Basic US Patent for metal (In, Sn, Rare Earths…).loading in scint liquids (RSR+EC Bell Labs 2004 ) 8% InLS (PC:PBD/MSB) hν / MeV BC505 Std h /MeV In 8%-photo Light Yield from Compton edges of 137 Cs  -ray Spectra (nm) Norm. Absorbance in 10 cm L(1/e)(InLS 8%) ~ L(PC Neat) ! ZVT39: Abs/10cm ~0.001;  L(1/e)(nominally) >>20 m InLS PC Neat Indium Liquid Scintillator Milestones unprecedented in metal LS technology LS technique relevant to many other applications e.g. reactor nu expts for θ 13

3D Digital Localizability of Hit within one cube  ~75mm precision vs. 600 mm (±2 σ) by TOF in longitudinal modules  x8 less vertex vol.  x8 less random coinc.  Big effect on Background  Hit localizability independent of event energy Test of transparent double foil mirror in New Detector Concept - The Scintillation Lattice Chamber Light propagation in GEANT4 Concept

Light loss by Multiple Fresnel Reflection 4x4x4m Cube Absorption length = 10m Upper limit ~1700pe/MeV (L=10m) - reach via antireflective coating on films? Adopt 1020 pe/MeV 7.5 cm cells Photoelectron yield versus number of cells:

100 keV event in 4x4x4m cube, 12.5cm cells Perfect optical surfaces : 20 pe (per channel) Rough optical surfaces : 20% chance of non- ideal optics at every reflection 12 pe in vertex + ~8 pe in “halo” Conclusion - Effect of non-smooth segmentation foils: No light loss - (All photons in hit and halo counted) Hit localization accuracy virtually unaffected Foil Surface Roughness and Impact on the Hit Definition

Signal Reconstruction Event localization relies on PMT hit pattern (NOT on signal timing) Algorithm finds best solution for event pattern to match PMT signal pattern System is overdetermined, hardly affected by unchannelled light Timing information + position  shower structure

Indium Radioactivity Background-The Final Frontier BGD E( ) -114 keV (e1) 116 keV (g2) 498 keV (g3) 115 In SIGNAL 115 In 115 Sn β 0 + n  (BS) (E max = 499 keV) 498 keV *Cattadori et al: 2003 β 1 (E max < 2 keV) (b = 1.2x10 -6 )* 115 Sn e/   Multiple 115 In decays simulate tag candidate in many ways

Indium Radioactivity Background 115 In  –decays in (quasi) prompt RANDOM coincidence produce a tag: Basic tag candidate: Shower near vertex (Nhit ≥ 3) - chance coincident with 115 In β in vertex Type A:A1 = β + BS  (E tot = 498 keV) (x1) A2 =  (498 keV) (x1) TypeB:2 β-decays (x10 -8 ) Type C:3 β-decays (x ) Type D:4 β-decays (x ) Background categories Strong suppression via energy Suppression via tag topology

Data: Main Simulation of Indium Events with GEANT4 ~ 4x10 6 In decays in one cell centered in ~3m 3 volume (2-3 days PC time) Analysis trials with choice of pe/MeV and cut parameters (5’ /trial) Indium Background Simulations and Analysis Analysis Strategy Primary selection - tag candidate shower events with Nhit ≥ 3 Classify all eligible events (Nhit ≥ 3) according to Nhit Optimize cut conditions individually for each Nhit class Main Cuts Total energy: g2+g3 Tag topology: Distance of lone  from shower

Final Result: Overall Background suppresion > At the cost of signal loss by a factor ~ 1.6  Tag analysis must suppress Background by ~2x10 4  Sufficient to generate ~4x10 6 n-tuples for the analysis Background Suppression - Analysis of Tag Candidates Signal /y /t In Bgd tot /y /t In Bgd A1 /y /t In Bgd A2 /y /t In Bgd B /y /t In RAW x Valid tag (Energy, Branching, Shower) in Space/Time delayed coinc. with prompt event in vertex x x x x ≥3 Hits in tag shower x x x x Tag Energy = 620 keV Tag topology4013 ± “Free” Cuts

Scintillator properties: InLS: 8% In L(1/e) = 1000cm LY (InLS) = 9000 h /MeV Detector Design: Typical LENS-Sol Design Figures of Merit – Work in Progress Cell Size mm Cube size m Pe yield /MeV Det Eff % pp- /t In/y Bgd /t In/y S/NM (In)* ton M (InLS) ton PMT % (3”) % (5”)

PMT Passive Shield Mirror InLS LS Envelope 5m 12m PMT Passive Shield Mirror InLS LS Envelope 5m PMT Passive Shield Mirror InLS LS Envelope InLS LS Envelope 5x5x5m 12m. CagesegmentationOpt. LENS Design Concept (not to scale) 125 ton InLS 10 t Indium ” PMT’s

5”PMT Passive Shield Mirror 5”PMT Passive Shield Mirror Opt segmentation cage InLS 500 mm InLS LS Envelope 500 mm InLS : 128 L PC Envelope : 200 L 12.5cm pmt’s : 108 MINILENS--Prototype Final Test detector for LENS

MINILENS: Global test of LENS R&D Test detector technology  Large Scale InLS  Design and construction Test background suppression of In radiations by Demonstrate In solar signal detection in the presence of high background Direct blue print for full scale LENS

Proxy pp nu events in MINILENS from cosmogenic 115 In(p,n) 115 Sn 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 “Proxy” pp- events in MINILENS

Next Step Test of all the concepts and the technology developed so far: MINI-LENS liter InLS scintillation lattice detector Summary ● In LS Technology ● Detector Design ● Background Analysis  Basic feasibility of In-LENS-Sol secure ● extraordinary suppression of In background (all other Bgd sources not critical) ● Scintillation Chamber – InLS only ● High detection efficiency  low detector mass ● Good S/N Major breakthroughs: IN SIGHT: Simple Small LENS (~10 t In /125 t InLS)

Large (50-100kT) Liquid Scintillation Detector For keV-GeV Multidisciplinary Science HYPER SCINTILLATION DETECTOR HSD

100 KT LIQUID SCINTILLATION DEVICE? Next generation device beyond CTF, Borexino, Kamland, LENS… The technology now has a large worldwide group of experts with experience/expertise in constructing and operating massive LS detectors (upto 1 kT so far), for precision low energy (>100 keV ) astro-particle physics Essential questions for a large scale project like this: What science can be achieved that may be unique? Can one achieve multidisciplinary functionality? Are the possible science questions of first rank impact? Can it be competitive with other large scale detector technologies in science payoff, cost. technical readiness …?

Working Group (Theory and Experiment): F.Feilitzsch, L. Oberauer (TU Munich0 R. Svoboda (LSU) Y. Kamyshkov, P. Spanier (U. Tennessee) J. Learned, S. Pakvasa (U. Hawaii) K. Scholberg (Duke U.) M. Pitt, B.Vogelaar, T. Takeuchi, C. Grieb, Lay Nam Chang, R. S. R (VT) Bring together earlier work: Munich Group -LENA (aimed at a European site) R. Svoboda et al Y. Kamishkov et al RSR

LS Technology (Targets in LS: 12 C, p) Pluses: +Signal x50 that of Cerenkov +Low Energy (>100 keV) Spectroscopy (in CTF (5T, 20% PMT coverage) 14 C spectrum >30 keV) +Heavy Particle Detection well below C-threshold +Tagging of rare events by time-space correlated cascades +Ultrapurity-ultralow bgds even < 5 MeV (radio “Wall”) +Technology of massive LS well established Minus: -Isotropic signal—no directionality Unique Tool for Anti-Neutrino Physics ==Nuebar tagging by delayed neutron capture by protons Very low fluxes (~1/cm 2 MeV) conceivable with care and effort: Good depth to avoid  -n cosmogenics (e.g. 9 Li—prefer no heavy element for n-capture) Efficient muon veto of n, std 5m water shield to cut n, PMT, rock  Ultrapurity to cut internal  < 5 MeV Locate far from high power reactors

Main Topics in Focus Particle Physics Proton Decay Long baseline Neutrino Physics—especially with nuebars Geophysical Structure and Evolution of Earth Global measurement of the antineutrinos from U, Th in the interior of the earth ( Fission Reactor at the center of the earth ??? ) Supernova Astrophysics and Cosmology Supernovae—Real time detection Relic Supernova Spectrum Pre-supernova Pair emission of C,O, Ne or Si burning

TerrestrialRadiogenicEnergy Sources Location 1) Radioactivity of U andTh(and others)MostlyCrustalLayer 2) Fission Reactor ?? Inner Core 3) Man-made Power Reactors Surface ALL ABOVE SOURCES EMIT ANTINEUTRINOS ANTINEUTRINO SPECTROSCOPY CAN PROBE THE EARTH Just as neutrino spectroscopy has probed the Sun TECHNOLGY MATURE AND AVAILABLE PARASITIC MEASUREMENT IN DETECTORS FOR OTHER PHYSICS TIMELY TO CONSIDER FOR NUSL Long Literature: Problem: G. Elders (1966)G. Marx (1969) Detection methods; Krauss et al Nature (and ref therein)...many others TerrestrialRadiogenicEnergy Sources Location 1) Radioactivity of U andTh(and others)MostlyCrustalLayer 2) Fission Reactor ?? Inner Core 3) Man-made Power Reactors Surface ALL ABOVE SOURCES EMIT ANTINEUTRINOS ANTINEUTRINO SPECTROSCOPY CAN PROBE THE EARTH Just as neutrino spectroscopy has probed the Sun TECHNOLGY MATURE AND AVAILABLE PARASITIC MEASUREMENT IN DETECTORS FOR OTHER PHYSICS TIMELY TO CONSIDER FOR DUSEL Long Literature: Problem: G. Elders (1966)G. Marx (1969) Detection methods; Krauss et al Nature (and ref therein)...many others Spectroscopy & Specific Model Tests: Raghavan et al PRL Rotschild et al, Geophys. Res. Lett. 25,

Homestake 4850’ Henderson MC South Pole(Amanda/ice 3 )

Homestake Henderson Power reactors Possible Nuclear Reactor Background Sources for HMSTK & Hndrsn

( RSR et al PRL 80 (635) 1998) Aug 2005—New Glimpse of U/Th Bump in Kamland! Birth of Neutrino Geophysics Situation like 1964 in solar Neutrinos

(RSR hep-ex/ a0 Reactor bgd/Kt/yr Kamioka: 775 Homestake: 55 WIPP: 61 San Jacinto: 700 Kimballton: ~100

Detect ν̃ e with tag. Solar pp C O, Ne) Si Odrziwolek et al Astro-ph/ M sun Star at 1kpc Pre SN ν emission from 20M sun Star via pair Annihilation

No K+ from 2-body nucleon decay can be seen directly many nuclear de-excitation modes not visible directly “stealth”muonsfrom atmospheric neutrinos serious background for proton decay, relic SN search Limitations fromCerenkovThreshold No K+ from 2-body nucleon decay can be seen directly many nuclear de-excitation modes not visible directly “stealth”muonsfrom atmospheric neutrinos serious background for proton decay, relic SN search Limitations fromCerenkovThreshold

Disappearance of n in 12 C leads to 20 MeV excitation of 11 C followed by delayed coincidences at few MeV energy This pioneering technique opens the door to a very different way of looking for nucleon decay –best facilitated in LS technique Kamyshkov and Kolbe (2002) HSD enables search for Mode-free Nucleon Decay

Conclusions: HSD will be a Major Science Opportunity Top notch multi-disciplinary science justifying cost (~300M?) 1. Geophysics 2. SN physics and cosmology 3. Proton/nucleon decay #1 not possible in any other detector—Uniqueness--Discovery #2 best served by low energy sensitivity-- higher event yields and access to high red shift cosmology— best chance for definitive landmark result #3 better opportunities in HSD than Cerenkov and at least as good handles as in LAr

Conclusions Henderson DUSEL offers attractive opportunities For Scintillation based detectors LENS and HSD That Between them cover a large swath of top class Science