Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010  13 from Global Fits current best limit sin 2 2θ 13 < CL Fogli, et al., arXiv:0905:3549 A. B. Balantekin and D. Yilmaz, J. Phys. G 35, (2008) sin 2 2  13 ~ ? Schwetz et al arXiv:

Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Theoretical Predictions for  13 Albright et al. arXiv:

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

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

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

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 -3 eV 2 90% CL, 3 years Double- CHOOZ (France) / /3008.8/8.84/2010, RENO (So. Korea) / /45016/169/ Daya Bay (China) (481) / 1985(1613) 260/910 40(  2) / Reactor θ 13 Experiments

Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Daya Bay, China RPCs water pool muon veto system experimental hall PMTs antineutrino detectors multiple detectors per site cross-check efficiency

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

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

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

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)

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 (%)

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

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

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

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 Gd-LS will be produced in multiple batches but mixed in reservoir on- site, to ensure identical detectors. λ=10m

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

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

Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Systematic Uncertainties Absolute measurement Relative measurement O( %) precision for relative measurement between detectors at near and far sites Detector-Related Uncertainties Ref: Daya Bay TDR

Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detector Assembly Jan 2010

Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Antineutrino Detector Dry Run one calibration system one PMT ladder

Karsten Heeger, Univ. of Wisconsin Yale University, March 1, 2010 Sensitivity of Daya Bay sin 2 2θ 13 < 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.

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

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

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

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

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