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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 13 from Global Fits current best limit sin 2 2θ 13 < 0.11 @90% CL Fogli, et al., arXiv:0905:3549 A. B. Balantekin and D. Yilmaz, J. Phys. G 35, 075007 (2008) sin 2 2 13 ~ 0.06-0.08? Schwetz et al arXiv:0808.2016
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Theoretical Predictions for 13 Albright et al. arXiv:0911.2437
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Reactor and Accelerator Experiments - disappearance experiment ν e → ν e - low-energy neutrinos (MeV) - no matter effects, baseline O(1 km) reactor ( e disappearance) - sin 2 2 13 is missing key parameter for any measurement of CP accelerator ( e appearance) CP violation mass hierarchy matter
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Precision Measurement of 13 with Reactor Antineutrinos Search for 13 in new oscillation experiment with multiple detectors ~1-1.8 km > 0.1 km 13 Large-amplitude oscillation due to 12 Small-amplitude oscillation due to 13 integrated over E Δm 2 13 ≈ Δm 2 23 detector 1 detector 2 νeνe Daya Bay Reactors: Powerful e source, multiple cores 11.6 GW th now,17.4 GW th in 2011
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Measured Ratio of Rates sin 2 2 13 Measure ratio of interaction rates in multiple detectors nearfar νeνe distance L ~ 1.5 km Concept of Reactor θ 13 Experiments Detector Mass Ratio, H/C mass measurement Detector Efficiency Ratio calibration
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Experiment Thermal Power (GW) Distances Near/Far (m) Depth Near/Far (mwe) Target Mass (tons) Start Date Sensitivity @2.5x10 -3 eV 2 90% CL, 3 years Double- CHOOZ (France) 8.6410/1050115/3008.8/8.84/2010, 20110.032 RENO (So. Korea) 17.3290/1380120/45016/169/20100.02 Daya Bay (China) 17.4363(481) / 1985(1613) 260/910 40( 2) / 80 20110.008 Reactor θ 13 Experiments
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Daya Bay, China http://dayawane.ihep.ac.cnhttp://dayawane.ihep.ac.cn/ RPCs water pool muon veto system experimental hall PMTs antineutrino detectors multiple detectors per site cross-check efficiency
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 liquid scintillator hall tunnel entrance Civil Construction Progress LS hall entrance near hall construction progress Jan 2010 liquid scintillator hall
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Daya Bay Antineutrino Detectors 8 “identical”, 3-zone detectors no position reconstruction, no fiducial cut target mass: 20t per detector detector mass: ~ 110t photosensors: 192 PMTs energy resolution: 12%/√E e + p → e + + n acrylic tanks photomultipliers steel tank calibration system Gd-doped liquid scintillator mineral oil
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detection events/day per 20 ton module Prompt Energy Signal 1 MeV Daya Bay near site 840 Ling Ao near site 760 Far site 90 6 MeV10 MeV Delayed Energy Signal → + Gd → Gd* 0.3 b 49,000 b → + p → D + (2.2 MeV) (delayed) e + p → e + + n → Gd + ’s (8 MeV) (delayed) Signal and Event Rates
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Energy Calibration and Efficiencies Prompt Energy Signal 1 MeV8 MeV 6 MeV10 MeV Delayed Energy Signal e + p → e + + n efficiency 98%efficiency 78% e + threshold: stopped positron signal using 68 Ge source (2x0.511 MeV) e + energy scale: 2.2 MeV neutron capture signal (n source, spallation) 1 MeV cut for prompt positrons: >99%, uncertainty negligible 6 MeV cut for delayed neutrons: 91.5%, uncertainty 0.22% assuming 1% energy uncertainty 6 MeV threshold: n capture signals at 8 and 2.2 MeV (n source, spallation)
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Daya Bay Antineutrino Detectors 3-Zone Design no position reconstruction, no fiducial cut for event identification Gd-LS (20 tons) = 5m (tunnel limitations) oil buffer (MO) thickness > 15cm buffer between PMT and OAV gamma catcher (LS) thickness thickness = 42.3 cm det. efficiency > 91.5% LSLS MOMO Efficiency (%)
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Detector Top/Bottom Reflectors z (cm) reflector flattens detector response specular reflectors consist of ESR® high reflectivity film on acrylic panels total pe without reflector with reflector
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Cerenkov Water Pool (2 layers) RPC’s Muon Veto System 1m outer water shield inner water veto The two-layer water pool and PMTs (962 in total) provides >2.5m water shield for neutron background and ~0.5 spatial resolution. Dayabay veto system provides a combined muon detect efficiency > 99.5%. RPC s: muon detect efficiency 98.6% and ~0.5m spatial resolution. Two-layer water pool: 962 PMTs, >2.5m water shield for neutron background, ~0.5m spatial resolution Daya Bay veto system provides a combined muon detection efficiency > 99.5%. PMTs
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Detector Calibration z(cm) automated calibration system → routine weekly deployment of sources LED light sources → monitoring optical properties e + and n radioactive sources (=fixed energy) → energy calibration R(cm) /E = 0.5% per pixel requires: 1 day (near), 10 days (far) tagged cosmogenic background (free) → fixed energy and time 68 Ge source Am-C + 60 Co source LED diffuser ball
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Gd-Liquid Scintillator Test Production 500L fluor-LAB Two 1000L 0.5% Gd- LAB 5000L 0.1% Gd-LS 0.1% Gd-LS in 5000L tank Daya Bay experiment uses 185 ton 0.1% gadolinium-loaded liquid scintillator (Gd- LS). Gd-TMHA + LAB + 3g/L PPO + 15mg/L bis-MSB 16 Gd-LS stability in 4-ton test days absorbance 4-ton test batch production in March 2009. Gd-LS will be produced in multiple batches but mixed in reservoir on- site, to ensure identical detectors. λ=10m
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Gd-TMHA 0.5% Gd-LAB mix 0.1% Gd-LS, 4t LAB+PPO (30g/L)+ bis- MSB (150mg/L), 0.4t 1.sit 24 hrs to drain the aqueous phase 2.add LAB for dissolution 1.transfer to clearance tank via filtration to sit 72 hrs for clearance 2.drain the residual water 0.5% Gd-LAB clear, 0.8t filtration/QC QC LAB, 2.8t GdCl3TMHA + 40-t Storage Tank QC/QA –chemical purification and precision control –A 4-t batch per day; 5 days per week Gd-Liquid Scintillator - 185t Production
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Detector Filling & Target Mass Measurement filling platform with clean room ISO Gd-LS weighing tank pump stations detector load cell accuracy < 0.02% Coriolis mass flowmeters < 0.1% Gd-LS MO LS 200-ton Gd-LS reservoir 20-ton ISO tank filling “pairs” of detectors
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Systematic Uncertainties Absolute measurement Relative measurement O(0.2-0.3%) precision for relative measurement between detectors at near and far sites Detector-Related Uncertainties Ref: Daya Bay TDR
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detector Assembly Jan 2010
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detector Dry Run one calibration system one PMT ladder
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Sensitivity of Daya Bay sin 2 2θ 13 < 0.01 @ 90% CL in 3 years of data taking 2010 start data taking with near site 2011 start data taking with full exp. Most sensitive reactor θ 13 experiment under construction.
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detector Response Detector Uniformity along radial R directionalong vertical symmetry axis (z-direction) R z Gd-LS boundary - GEANT4-based simulations - idealized 3-zone detector plus reflectors - developing realistic geometry in simulations
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Cerenkov Water Pool (2 layers) RPC’s Muon Veto System 1m outer water shield inner water veto The two-layer water pool and PMTs (962 in total) provides >2.5m water shield for neutron background and ~0.5 spatial resolution. Dayabay veto system provides a combined muon detect efficiency > 99.5%. RPC s: muon detect efficiency 98.6% and ~0.5m spatial resolution. Two-layer water pool: 962 PMTs, >2.5m water shield for neutron background, ~0.5m spatial resolution Daya Bay veto system provides a combined muon detection efficiency > 99.5%. PMTs
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detector Event Distributions R 2 distribution of neutron production point Gd-LS LS spill out 12% / E 1/2 reconstructed energy resolution Geant4-based simulations R 2 distribution of neutron capture position
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detector Performance Detection Efficiencies Geant4-based simulations 6 MeV10 MeV Delayed n Signal 6 MeV cut for delayed neutrons: 91.5%, uncertainty 0.22% assuming 1% energy uncertainty Prompt e + Signal 1 MeV cut for prompt positrons: >99%, uncertainty negligible
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Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Daya Bay Background Summary 9 Li signal backgrounds from beta-delayed neutron emission isotopes 8 He and 9 Li will have to be measured and subtracted 840
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