Low Energy Neutrinos Neutrino Luminosity of the Sun & LENS Neutrino Oscillation Workshop Conca Specchiulla, September 11, 2006 Christian Grieb Virginia Tech

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 LENS-Sol Signal = SSM(low CNO) + LMA x Detection Efficiency   Rate: pp 40 pp ev. /y /t In  2000 pp ev./ 5y/10t In  ±2.5%  Design Specification: S/N ≥ 3 LENS Expected Result: Low Energy Solar -Spectrum Access to pp spectral shape for the first time Signal (  = 4.76 µs) >98% Flux <2MeV pp:  = 64% 7 Be:  = 85% pep:  = 90%

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Test of Solar Models Solar models predict relative intensities in the pp-chain Reaction rates depend on temperature profile and abundances Cross check with measured fluxes (using neutrino oscillation physics) Data taken from John N. Bahcall, M.H. Pinsonneault, Phys.Rev.Lett.92, (2004) Solar Neutrino fluxes at the earth according to SSM

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Neutrino Inferred Solar Luminosity Nuclear fusion reactions in the solar core pp-chain + CNO cycle H.A. Bethe Phys.Rev.55, 434 (1939) No solar model needed J. N. Bahcall and R. Ulrich, Rev. Mod. Phys. 60, No. 2, p. 297 (1988) Nuclear reactions in the pp-chain:

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Solar Luminosity: Neutrino vs. photon Will be met under these conditions: 1.Fusion reactions are the sole source of energy production in the sun 2.The sun is in a quasi-steady state (change in 40,000 years is negligible) 3.The neutrino oscillation model is correct & no other physics involved; From a single detector: Test of astrophysics, solar model (absolute fluxes); Test of neutrino physics (LMA-MSW at low E, NSI, mass-varying s, CPT invariance,  13, …) (relative fluxes) Measured neutrino fluxes at earth + oscillation physics nuclear reaction rates energy release in the sun Solar luminosity as measured by photon flux = ? Energy Balance:

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Main contributions:pp Be0.074 (CNO0.014) 8 B Neutrino inferred Luminosity of the Sun - Experimental Status Measured neutrino fluxes at the earth: 8 B(SK, SNO) known very well 7 Be + 8 B (Cl) sensitive mostly to 8 B pp + 7 Be + 8 B (Ga) 7 Be (Borexino, Kamland – in the future)  in principle can deduce pp- flux Problem: disentangling fluxes from individual neutrino sources Predicted relative neutrino fluxes at the sun (SSM): 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)

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Temperature in the Solar Core impacts Neutrino Spectra, not just relative fluxes Neutrino Production Temperature Profile J. N. Bahcall and R. Ulrich, Rev. Mod. Phys. 60, No. 2, p. 297 (1988)

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 hep: Relative kinetic particle energies add to the Q-value of capture and fusion reactions. Not all energies contribute evenly: Temperature in the Solar Core impacts Neutrino Energies, not just relative fluxes C. Grieb and R.S. Raghavan, hep-ph/ (2006) E0E0 pep pp pp- and pep neutrino production temperature and related Gamow peak energy: 7 Be electron capture: maxwellian energy distribution shifts mean energy of 7 Be line by  ~ 1.29 keV pp-fusion: Gamow Peak at pp endpoint shifted up by ~5.2keV Maxwellian energy distribution X Tunneling probability J.N. Bahcall, Phys. Rev. D 44(6), 1644(1991) pep: combination, delta  ~ 6.6 keV J.N. Bahcall, Phys. Rev. D 49(8), 3923 (1994)

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Measurement of the Gamow Energy of pp- fusion in the sun with (improved) LENS C. Grieb and R.S. Raghavan, hep-ph/ (2006) Top:pp- spectrum with/without Gamow shift Bottom: Signal spectrum in LENS with/without Gamow shift 12t Indium - 6years -  E/E=6% at 300keV Measured Gamow shift in improved LENS: simulations with ~3000 pp events each  =1.62keV Conclusion: Slightly improved LENS can detect the predicted Gamow shift in the pp- endpoint  E=5.2keV with 95% confidence.

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Background Challenge: Indium-target is radioactive! (t = 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 Requires good spacial resolution 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 Tag: Delayed emission of (e/  )+  Threshold: 114 keV  pp- ’s 115 In abundance: ~ 96%

 Luminosity and LENS Christian Grieb, Virginia Tech, September 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 Stability: at least 1 year 5. InLS Chemistry - Robust Basic Bell Labs Patent, filed 2001, awarded % 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 Status Milestones unprecedented in metal LS technology LS technique relevant to many other applications

 Luminosity and LENS Christian Grieb, Virginia Tech, September D Digital Localizability of Hit within one cube  ~75mm precision vs. 600 mm (±2σ) 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 double foil mirror in New Detector Technology - The Scintillation Lattice Chamber Light propagation in GEANT4 Concept

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Indium  - -Background Topology – Space / Time coincidence Background Signal E( ) -114 keV 116 keV 498 keV 115 In 115 Sn e/    =4.76  s 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). Signal Signature: Prompt e - ( ) followed by low energy (e - /  ) ( ) and Compton-scattered  ( ) 115 In 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 

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Results of GEANT4 Monte Carlo simulation (cell size = 7.5cm, S/N=3) Signal (pp) y -1 t In) -1 Bgd (In) y -1 (t In) -1 RAW rate x A. Tag in Space/Time delayed coincidence with prompt event in vertex x 10 5 B. + ≥3 Hits in tag shower x 10 4 C. +Tag Energy = 614 keV44306 D. +Tag topology4013 ± 0.6 Background rejection steps: A.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 ~ through time/space coincidence Indium  - -Background Discrimination

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Test all the concepts and the technology developed so far & demonstrate Indium solar signal detection: MINI-LENS liter InLS scintillation lattice detector Summary ● Indium liquid scintillator synthesis ● New detector technology (Scintillation Lattice Chamber) ● GEANT4 Simulation of Indium  - background  Basic feasibility of In-LENS-Sol secure (10t In, 125t In-LS) Major breakthroughs in LENS: Science in LENS: Measure solar -spectrum below 2MeV  Luminosity of the sun  Gamow shift of pp- spectrum probes the T profile  Test of Astrophysics & physics in one experiment Next Step:

 Luminosity and LENS Christian Grieb, Virginia Tech, September 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:R. L. Hahn, M. Yeh; U. N. Carolina:A. Champagne; ORNL:J. Blackmon, C. Rascoe, A. Galindo-Uribarri, Q. Zeng; Princeton U. :J. Benziger; Virginia Tech:Z. Chang, C. Grieb, M. Pitt, R.S. Raghavan, D. Rountree, R.B. Vogelaar; LENS-Sol / LENS-Cal Collaboration (Russia-US: 2004-) New collaborators cordially invited!

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 Additional Slides

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 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

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 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

 Luminosity and LENS Christian Grieb, Virginia Tech, September ”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 Final Test detector for LENS

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 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

 Luminosity and LENS Christian Grieb, Virginia Tech, September 2006 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