LENS, MINILENS STATUS R. S. Raghavan Virginia Tech For The LENS - PowerPoint PPT Presentation

LENS, MINILENS STATUS R. S. Raghavan Virginia Tech For The LENS Collaboration TAUP 07 Sendai, Japan Sep 13, 2007 Raghavan—TAUP07-9-12-07

LENS—Low Energy Neutrino Spectroscopy Tagged � � � �������������������������� �� � � 115 115 * 115 In e Sn 2 + Sn � � + � + � � e signal delay Tag cascade LENS is the only CC detector developed to date for low energy solar neutrinos R&D Funded now by NSF [ Placed in MUST FUND Category by two Review Panels] Raghavan—TAUP07-9-12-07

LE$NS Detection Scheme Unique: • Specifies � ������� The Indium Low Energy Neutrino Tag The Indium Low Energy Neutrino Tag � � � � � �� �� ������� � e e e e � ��� �������������������� 7/2 + 7/2 + 7/2 + 7/2 + 1857 1857 1857 1857 �������������� � �� � � ���� � � B(GT) ~0.01; Q B(GT) ~0.01; Q B(GT) ~0.01; Q B(GT) ~0.01; Q � =1362 � =1362 � =1362 � =1362 ���� � ����������� � �� � �������� � = 231 μ s � = 231 μ s � = 231 μ s � = 231 μ s � � ��������������������������� � � � 11/2 - 11/2 - 11/2 - 11/2 - 713.6 713.6 713.6 713.6 115 In(p,n) 115 In(p,n) 115 In(p,n) 115 In(p,n) e 1 e 1 e 1 e 1 � ��������������������������� � 100.8 (e/ � =5.7 ) 100.8 (e/ � =5.7 ) 100.8 (e/ � =5.7 ) 100.8 (e/ � =5.7 ) � = 4.76 μ s � = 4.76 μ s � = 4.76 μ s � = 4.76 μ s ����������������������� � � � � ��������� 7/2 + 7/2 + 7/2 + 7/2 + 612.8 612.8 612.8 612.8 ��������� � = 114 � = 114 � = 114 � = 114 (e/ � ) 2 115.6 ( e/ � = 0.96 ) (e/ � ) 2 115.6 ( e/ � = 0.96 ) (e/ � ) 2 115.6 ( e/ � = 0.96 ) (e/ � ) 2 115.6 ( e/ � = 0.96 ) B(GT) = 0.17; Q B(GT) = 0.17; Q B(GT) = 0.17; Q B(GT) = 0.17; Q � �������� � � � � ������������������� � �������������������� � ������ �� � � � � �������� � = 16 ps � = 16 ps � = 16 ps � = 16 ps 9/2 + 9/2 + 9/2 + 9/2 + 3/2 + 3/2 + 3/2 + 3/2 + 497.3 497.3 497.3 497.3 ������ 115 In ( 95.7%) 115 In ( 95.7%) 115 In ( 95.7%) 115 In ( 95.7%) � � ��� ���������������� � ������������ � = 6.4x10 14 y � = 6.4x10 14 y � = 6.4x10 14 y � = 6.4x10 14 y � 3 � 3 � 3 � 3 497.3 497.3 497.3 497.3 �� � � ������������ � � ����������������� � max = 498.8 � max = 498.8 � max = 498.8 � max = 498.8 ���������������� � � � ������ � ����� �� � � 1/2 + 1/2 + 1/2 + 1/2 + 0 0 0 0 ��� 115 Sn 115 Sn 115 Sn 115 Sn � ����������������������� Raghavan—TAUP07-9-12-07

Expected Result: Low Energy Solar � -Spectrum Tag Delayed coincidence LENS-Sol Signal Signal area Time Spectrum = Bgd SSM(low CNO) + LMA S/N = 1 x S/N = 3 Detection Efficiency � Coincidence delay time μ s pp: � = 64% Fitted Solar Nu Spectrum (Signal+Bgd) /5 yr/10 t In 7 Be: � = 85% pp pep: � = 90% S/N=3 7 Be � Rate: pp 40 /y /t In Indium Bgd � 2000 pp ev. / 5y � ±2.5% CNO � Design Goal: S/N � 3 pep Access to pp spectral Shape for the first time 7 Be* Raghavan—TAUP07-9-12-07 Signal electron energy (= E � – Q) (MeV)

Science from LENS—Hi precision low energy Nu fluxes (pp � 3-4%) 1.Neutrino Physics –Energy dependence of P ee � Oscillation Phenomenology 2. Solar Luminosity vs Photon Lluminosity— Astrophysics/Neutrino physics 3. Gamow Energy of pp fusion—Energy production in sun 4. Physics beyond Std model—Sterile Neutrinos from LENS+Source 5. Solar model independent Fluxes –CC+NC (LENS + Borexino) Raghavan—TAUP07-9-12-07

New Technology of LENS Developed in last three years Raghavan—TAUP07-9-12-07

Technology and Bgd Control 0.05 Transparency of 10/06/05 Normalized Absorbance 0.04 < Towards Hi Precision pp neutrino flux > InLS 01/23/06 03/22/06 0.03 05/31/06 0.02 8.6 m after 8 months 0.01 • Hi Quality InLS 0 • New Detector Design -0.01 350 390 430 470 510 550 590 630 670 • Background Analysis Insights � -115 In decay bgd � (nm) UV/Vis absorbance of zVt45 (pH 6.88) with time suppressed � S/N ~3 for first time Status Design of Detector Cubic Lattice Chamber InLS: In content >8% Light attenutation L(1/e) >8m Signal Eff Pe/MeV 900 Indium Mass(1900 pp/5y) 10 ton Total Mass 125 ton PMT’s 13,300 Neutrino detection eff. 64% Raghavan—TAUP07-9-12-07

Indium Liquid Scintillator Status BC505 Std 8% InLS (PC:PBD/MSB) 12000 h � /MeV 10800 h � / MeV Milestones unprecedented 10000 in metal LS technology 1000 LS technique relevant to 100 many other applications In 8%-photo 10 Light Yield from Compton edges of 137 Cs � -ray Spectra 1. Indium concentration ~8%wt 1 (higher may be viable) 0 50 100 150 200 250 2. Scintillation signal efficiency 0.030 (working value): 8000 h � /MeV L(1/ e )(InLS 8%) ~ L(PC Neat) ! Norm. Absorbance in 10 cm 0.025 3. Transparency at 430 nm: ZVT39: Abs/10cm ~0.001; 0.020 L(1/ e ) (working value): 8m � L(1/e)(nominally) >>20 m 4. Chemical and Optical 0.015 Stability: at least 1 year InLS 0.010 5. InLS Chemistry – Robust 0.005 New = LAB based InLS PC Neat 0.000 Basic Bell Labs Patent, -0.005 � (nm) Chandross, Raghavan—TAUP07-9-12-07 350 390 430 470 510 550 590 630 670 Raghavan

New Detector Technology –hi event position localization The Scintillation Lattice Chamber Test of double foil Light channeling in 3-d totally Demonstration Acrylic Model mirror in liq. @~2bar Internally reflecting cubic Lattice GEANT4 sim. of concept. 3D Digital Localizability of Hit within one cube � ~75mm precision vs. 600 mm (±2 � ) by TOF in longitudinal modules � x8 less vertex vol. � x8 less random coinc. � Big effect on Background � Hit localizability independent of event energy Raghavan—TAUP07-9-12-07

Raghavan—TAUP07-9-12-07

Lattice Structure Single Foil Double Foil Solid teflon segmentation Double-layer (air-gap) lattice Raghavan—TAUP07-9-12-07

Raghavan—TAUP07-9-12-07

Raghavan—TAUP07-9-12-07

Indium � - -Background Structure – Space / Time coincidence Signal Signal Signature: E( � ) -114 keV Prompt e - ( )followed by � =4.76 μ s low energy (e - / � ) ( ) 115 In e/ � 116 keV and Compton-scattered � ( ) ->time/space coincidence � 497 keV -> tag fixed energy 613keV ->compton scattered shower 115 Sn Background: Bgd Random time and space coincidence � 1 (E max < 2 keV) between two � -decays ( ); 115 In (b = 1.2x10 -6 )* Extended shower ( ) can be created by: a) 498 keV � from decay to excited state; � 0 + n � (BS) � 498 keV b) Bremsstrahlungs � -rays created by (E max = 499 keV) � ; c) Random coincidence (~10 ns) of more � -decays; 115 Sn Or any combination of a), b) and c). Raghavan—TAUP07-9-12-07

Indium � - -Background Discrimination Background rejection steps for pp detection (other neutrinos detected free of Indium background): 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; Results of GEANT4 Monte Carlo simulation (cell size = Signal (pp) Bgd (In) Reduction 7.5cm, S/N=3) y -1 t In) -1 by ~3 . 10 7 y -1 (t In) -1 through RAW rate 62.5 79 x 10 11 time/space coincidence A. Tag in Space/Time delayed coincidence 50 2.76 x 10 5 with prompt event in vertex B. + � 3 Hits in tag shower 46 2.96 x 10 4 C. +Tag Energy = 614 keV 44 306 Raghavan—TAUP07-9-12-07 D. +Tag topology 40 13 ± 0.6

Neutrino Phenomenology – from LENS In the first 2 years (no calibration with � -source needed ): • 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? Low Energy (see above) Neutrinos: • CPT Invariance of Neutrinos? Only way to so far LMA only from Kamland , is this true � answer these e also for “neutrinos” ? � questions ! e • RSFP/ Nu magnetic moments Time Variation of pp and 7 Be signals ? (No Var. of 8 B nus !) (Chauhan et al JHEP 2005) Raghavan—TAUP07-9-12-07