1. AAP 2012 meeting, Honolulu Jelena Maricic University of Hawaii October 4, 2012

2. Executive Summary

3. Summary of 13 measurements from reactors 2011-2012 Daya Bay 13 ~8.7 (~8 zero exclusion) RENO 13 ~9.8 (~6 zero exclusion) Double Chooz 13 ~9.6 (~3 zero exclusion)

4. Summary of 13 measurements from beams MINOS T2K 13 ~7 (NH) 13 ~9 (IH) 13 ~9 (NH) 13 ~10 (IH) ~2 zero exclusion ~3 zero exclusion

5. Summary of 13 measurements Global fit from Daya Bay, RENO, Double Chooz and T2K: 1 2 3 4 N Fogli, Lisi, Marrone, Montanino, Palazzo, Rotunno: hep-ph/1205.5254 (2012) Sin 2 13 = 0.0241 ± 0.0025 (NH) Sin 2 13 = 0.0244 ± 0.0025 (IH) 13 = 8.9 ± 0.9 (~10% relative uncertainty)

6. Prospects 13 measured to be non zero with > 7 C.L. In the next 3 years expected to be known with 5% uncertainty Going from the unknown to the best measured neutrino mixing angle: 2003-2012 But there is more to this measurement…

7. Outline Introduction Review of the experiments Results of measurement 13 Prospects Material adopted from presentations from NOW2012 and ISNP 2012, from members of MINOS, T2K, Double Chooz, Daya Bay and RENO

8. Introduction

9. Starting point in 2003: CHOOZ Last non-measured neutrino mixing angle! Only the upper limit on the value of angle θ 13 was set! CHOOZ experiment constraint: ( e e disappearance exp) @ m 2 atm = 2.3 10 -3 eV 2 sin 2 (2θ 13 ) < 0.15 (90% C.L) CHOOZ experiment R = 1.01 2.8%(stat) 2.7%(syst) e x M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374 13 < 11

10. 13 central to fundamental questions CP-violation phase and mass hierarchy Solar 12 ~ 30° Atmospheric 23 ~ 45° (SK + MINOS) Little mixing angle 13 < 11 ° (circa 2011) (CHOOZ) Value of θ 13 directly influences prospects of measuring CP violation phase in the weak sector! 13 impacts measurements on ~few 100 m scale and above Interesting for nuclear reactor monitoring with neutrinos Δm 2 21 =(7.50 +0.19 -0.20 )×10 -5 eV 2 (KamLAND) Δm 2 32 =(2.32 +0.12 -0.08 )×10 -3 eV 2 (MINOS)

11. Hints on 13 from global fits in 2005/2008 Fogli, Lisi, Marrone, Palazzo, Rotunno: hep-ph/0806.2649v2 (2008) sin 2 13 = 0.9 +2.3 0.9 × 10 2 Fogli, Lisi, Marrone, Palazzo: hep-ph/0506083 (2005) sin 2 13 = 0.016 ± 0.010 13 ~ 5 13 ~ 7 Large uncertainty and low non-zero exclusion level.

12. Global fit from KamLAND in March 2011 KamLAND collaboration: hep-ex/1009.4771 sin 2 13 = 0.020 ± 0.016 13 ~ 8 Large uncertainty and low non-zero exclusion level.

13. Review of 13 experiments

14. 13 Measurement Strategies Use muon neutrinos from accelerator: appearance search for electron neutrinos MINOS T2K Use electron antineutrinos from nuclear reactor: disappearance search CHOOZ Double Chooz Daya Bay RENO

15. 13 and Beam Experiments MINOS T2K T2K uses off-axis beams to achieve: -Increased flux near oscillation max -Reduced high energy NC bkg µ µ e e

16. 13 and Reactor Experiments Reactor Near DetectorFar Detector E ν ~ 4 MeV (Flux)L 2 L ~1.5km < 14% No Oscillations Oscillated e e High precision measurement required: systematic error ~0.5%

17. 13 & Beam Experiments Appearance probability : dependences in sin(2 13 ), sin( 23 ), sign( m 2 31 ), -CP phase in [0,2 ] 13 & Reactor Experiments ~ a few MeV only disappearance experiments sin 2 (2 13 ) measurement independent of -CP P( e e ) = 1 - sin 2 (2 13 )sin 2 ( m 2 31 L/4E) + O( m 2 21 / m 2 31 ) weak dependence in m 2 21 a few MeV e + short baselines negligible matter effects (O[10 -4 ] ) sin 2 (2 13 ) measurement independent of sign( m 2 13 )

18. Results of measurement 13 with beams

19. MINOS Experiment 735 km MINOS - Main Injector Neutrino Oscillation Search Two functionally identical detectors to reduce systematics Near Detector 1 km from target 94 m underground, 225 mwe Measures the energy spectrum and beam composition Far Detector 735 km from target 700 m underground, 2070 mwe Re-measures the neutrino beam composition Near Detector 980 tons Far Detector 5,400 tons

20. Steel/scintillator tracking calorimeters Alternate orthogonal orientation planes Steel absorber 2.54 cm thick Scintillator strips 4.1 cm wide, 1.0 cm thick 1 GeV muons penetrate 28 layers Longitudinal sampling = 1.4 radiation lengths Optical WLS fiber readout to multi-anode PMTs Detector Technology Multi-anode PMT Extruded PS scint. 4.1 x 1 cm WLS fiber Clear Fiber cables 2.54 cm Fe U V planes +/- 45 0 Magnetized = 1.3T Muon energy from range/curvature Distinguish μ + from μ - tracks

21. Neutrino Interactions in Detectors transverse direction e-e- - beam direction color scale represents energy deposition Charged Current x Neutral Current e Charged Current long μ track & possible hadronic activity at vertex short with compact EM shower profile short with diffuse shower

22. 120 GeV protons Focusing Horns 2 m 675 m15 m 30 m Target Neutrino mode Horns focus π +, K + Decay Pipe π-π- π+π+ νμνμ νμνμ Monte Carlo Neutrino Mode

23. Antineutrino Mode 120 GeV protons Focusing Horns 2 m 675 m15 m 30 m Target Neutrino mode Horns focus π +, K + Decay Pipe π+π+ π-π- νμνμ νμνμ Monte Carlo Antineutrino mode Horns focus π -, K -

24. ν e Appearance Measurement sensitive to neutrino mixing angle θ 13, δ CP, mass ordering In matter, ν e CC scattering modifies oscillation probability ~30% in MINOS

25. 10.6×10 20 POT ( ν mode) Electron Appearance in FHC and RHC Beam 3.3×10 20 ( ν mode) ν mode Expected (LEM>0.7): 69.1 (background, if θ 13 =0) 26.0 (signal, if sin 2 (2θ 13 )=0.1) Observe: 88 events ν mode Expected (LEM>0.7): 10.5 (background, if θ 13 =0) 3.1 (signal, if sin 2 (2θ 13 )=0.1) Observe: 12 events Library Event Matching (LEM)

26. e Appearance: ν and Combined Contour

27. Second generation long-baseline neutrino-oscillation experiment; High intensity almost pure beam from Main Ring in J-PARC is shot toward the Super-Kamiokande detector 295km away. from Tokai to Kamioka The physics data-taking started in Jan. 2010, and stopped in March 2011 by the earthquake. Resumed almost a year later. J-PARC in JAEA Tokai Tokyo Kamioka KEK T2K experiment J-PARC in JAEA Super-Kamiokande J-PARC

34. Results of measurement 13 with reactors

35. Locations Double Chooz Daya Bay RENO

36. Configurations Double Chooz Daya Bay 300 mwe 115 mwe 1 km400 m

37. Reactor Neutrino Detection Signature Reactors as neutrino sources: Chooz: P =2x4.25 GW th N ~2x10 21 s -1 Neutrino detection via inverse decay Distinctive two-step signature: -prompt event Photons from e + annihilation E e = E - 0.8 MeV + O(E e /m n ) -delayed event Photons from n capture on dedicated nuclei (Gd) t ~ 30 s E ~ 8 MeV Gadolinium Target: Gd doped scintillator 1 g/l Gd in LS

38. The Double Chooz Far Detector Outer Veto (OV) plastic scintillator strips Outer Steel Shielding 250 t steel (15 cm) Inner Veto (IV) 90 m 3 of scintillator in a steel vessel (10 mm) equipped with 78 PMTs (8 inches) Buffer 110 m 3 of mineral oil in a steel vessel (3 mm) equipped with 390 PMTs (10 inches) γ-Catcher (GC) 22.3 m 3 scintillator in an acrylic vessel (12 mm) Target 10.3 m 3 scintillator doped with 1g/l of Gd compound in an acrylic vessel (8 mm) ~7m Calibration Glove Box

39. Daya Bay

41. 13 Measurement with DC Far

42. Interaction Cross-Section Recalculations of spectra introduced normalization shift; anomaly? Th.A. Mueller et al, Phys.Rev. C83(2011) 054615. P. Huber, Phys.Rev. C84 (2011) 024617

43. Reference Spectra + Bugey4 Anchor Normalize to Total Rate Measurement of Bugey4 Reduces reactor normalization uncertainty from 2.70% to 1.76%

44. Neutrino Candidate Selection Prompt signal Evis = [0.7, 12.2] MeV Delayed signal Evis = [6.0, 12.0] MeV Delayed Coincidence Δt = [2, 100] µsec Require Δt μ > 1 msec PMT light noise rejection cuts PMT hits approx. homogeneous PMT hits approx. coincident in time Multiplicity conditions: No extra events around signal Background rejection: No coincident signal in OV Require Δt μ > 500 msec if E μ > 600 MeV Plus three irreducible backgrounds: Accidentals Cosmogenic 9 Li Fast neutrons/stopping muons

45. Neutrino Candidate Selection Prompt signal Evis = [0.7, 12.2] MeV Delayed signal Evis = [6.0, 12.0] MeV Delayed Coincidence Δt = [2, 100] µsec Require Δt μ > 1 msec PMT light noise rejection cuts PMT hits approx. homogeneous PMT hits approx. coincident in time Multiplicity conditions: No extra events around signal Background rejection: No coincident signal in OV Require Δt μ > 500 msec if E μ > 600 MeV Preliminary Trigger efficiency Threshold at 400keV (ε=50%) ε=100% above 700keV Minimum visible energy of ν signal Prompt energy cut

46. Neutrino Candidate Selection Prompt signal Evis = [0.7, 12.2] MeV Delayed signal Evis = [6.0, 12.0] MeV Delayed Coincidence Δt = [2, 100] µsec Require Δt μ > 1 msec PMT light noise rejection cuts PMT hits approx. homogeneous PMT hits approx. coincident in time Multiplicity conditions: No extra events around signal Background rejection: No coincident signal in OV Require Δt μ > 500 msec if E μ > 600 MeV

47. Neutrino Candidate Selection Prompt signal Evis = [0.7, 12.2] MeV Delayed signal Evis = [6.0, 12.0] MeV Delayed Coincidence Δt = [2, 100] µsec Require Δt μ > 1 msec PMT light noise rejection cuts PMT hits approx. homogeneous PMT hits approx. coincident in time Multiplicity conditions: No extra events around signal Background rejection: No coincident signal in OV Require Δt μ > 500 msec if E μ > 600 MeV

48. Neutrino Candidate Selection Prompt signal Evis = [0.7, 12.2] MeV Delayed signal Evis = [6.0, 12.0] MeV Delayed Coincidence Δt = [2, 100] µsec Require Δt μ > 1 msec PMT light noise rejection cuts PMT hits approx. homogeneous PMT hits approx. coincident in time Multiplicity conditions: No extra events around signal Background rejection: No coincident signal in OV Require Δt μ > 500 msec if E μ > 600 MeV

49. Neutrino Candidate Selection Prompt signal Evis = [0.7, 12.2] MeV Delayed signal Evis = [6.0, 12.0] MeV Delayed Coincidence Δt = [2, 100] µsec Require Δt μ > 1 msec PMT light noise rejection cuts PMT hits approx. homogeneous PMT hits approx. coincident in time Multiplicity conditions: No extra events around signal Background rejection: No coincident signal in OV Require Δt μ > 500 msec if E μ > 600 MeV 41% of 9 Li BG is rejected by additional muon veto (~5% live-time loss) 28% of fast neutron/stop μ BG is rejected by OV anticoincidence

50. Candidate Rate Variation Before 9Li reduction cut, no OV anticoincidence applied Not background-subtracted Rate consistent with expectation

51. Cross-check: Reconstructed Vertex Position Events well-localized within target Note: no spatial cuts applied in candidate selection

52. Detector Calibration 1. PMT and electronics gain non-linearity calibration LED light injection system 2. Correct for position dependence Spallation neutron H captures 3. Correct for time stability Spallation neutron Gd captures 4. Energy scale Radioactive sources deployed into ν-target and γ-catcher Energy Calibration Neutron Detection Efficiency Energy & time window, Gd fraction, spill in/out effects 252 Cf source deployed into ν-target and γ-catcher

53. Backgrounds Accidentals Prompt: radiation hit on PMT Delayed: spallation neutron capture Prevented by radiopurity & shielding Measured from off-time windows: 0.261 +/- 0.002 day -1 Cosmogenic 9 Li Prompt: beta emission Delayed: neutrons from long-lived decays Measured from Δt μ & spatial muon coincidence: 1.25 +/- 0.54 day -1 Fast-n & Stopping muons Prompt: proton recoil or muon track Delayed: neutron capture or muon decay Measured from high-energy spectrum: 0.67 +/- 0.20 day -1

54. Backgrounds Accidentals Prompt: radiation hit on PMT Delayed: spallation neutron capture Prevented by radiopurity & shielding Measured from off-time windows: 0.261 +/- 0.002 day -1 Cosmogenic 9 Li Prompt: beta emission Delayed: neutrons from long-lived decays Measured from Δt μ & spatial muon coincidence: 1.25 +/- 0.54 day -1 Fast-n & Stopping muons Prompt: proton recoil or muon track Delayed: neutron capture or muon decay Measured from high-energy spectrum: 0.67 +/- 0.20 day -1 Preliminary

55. Backgrounds Accidentals Prompt: radiation hit on PMT Delayed: spallation neutron capture Prevented by radiopurity & shielding Measured from off-time windows: 0.261 +/- 0.002 day -1 Cosmogenic 9 Li Prompt: beta emission Delayed: neutrons from long-lived decays Measured from Δt μ & spatial muon coincidence: 1.25 +/- 0.54 day -1 Fast-n & Stopping muons Prompt: proton recoil or muon track Delayed: neutron capture or muon decay Measured from high-energy spectrum: 0.67 +/- 0.20 day -1

56. Backgrounds Accidentals Prompt: radiation hit on PMT Delayed: spallation neutron capture Prevented by radiopurity & shielding Measured from off-time windows: 0.261 +/- 0.002 day -1 Cosmogenic 9 Li Prompt: beta emission Delayed: neutrons from long-lived decays Measured from Δt μ & spatial muon coincidence: 1.25 +/- 0.54 day -1 Fast-n & Stopping muons Prompt: proton recoil or muon track Delayed: neutron capture or muon decay Measured from high-energy spectrum: 0.67 +/- 0.20 day -1 White: IBD Signal Red: Best-fit Spectrum Grey: Tagged background events White: IBD Signal

57. Check Rate vs. Reactor Power 2 events observed in 0.84 days livetime with both reactors off (= 2.2 event/day) Background rate consistent with estimation (2.2 ±0.6 event/day) Best fit to expected rate: sin 2 2θ 13 = 0.19 ± 0.06 BG rate = 2.9 ± 1.1 event/day arXiv:1207.6632

58. Summary of Rate UncertaintiesSource Uncertainty w.r.t. signal Statistics1.1% Flux1.7% Detector Energy response 0.3%1.0% E delay containment 0.7% Gd fraction 0.3% Δt cut 0.5% Spill in/out 0.3% Trigger efficiency <0.1% Target H 0.3% BackgroundAccidental<0.1%1.6% Fast-n + stop μ 0.5% 9 Li 1.4%

59. Summary of Candidates Both Reactors OnOne Reactor P th < 20% Total Livetime [days]139.2788.66227.93 IBD Candidates608821618249 Prediction Reactor B1 ν2910.9774.63685.5 Reactor B2 ν3422.41331.74754.1 9 Li174.1110.8284.9 FN & SM93.359.4152.7 Accidentals36.423.159.5 Total Prediction6637.12299.78936.8 Data divided into two integration periods based on reactor power Allows use of changing signal/background ratio in fit

60. Double Chooz Prompt Spectrum Data w/ Stat. Error Bars Best Fit Prediction (w/ Syst. Errors) Null Oscillation Prediction Backgrounds

61. Rate+Shape:sin 2 2θ 13 = 0.109 ± 0.030 (stat.) ± 0.025 (syst.) χ 2 /d.o.f. = 42.1/35 Rate-only:sin 2 2θ 13 = 0.170 ± 0.035 (stat.) ± 0.040 (syst.) Frequentist analysis: sin 2 2θ 13 = 0 excluded at 99.8% (2.9σ) Presented in arXiv:1207.6632, accepted by PRD

62. RENO 13 Measurement

73. Daya Bay 13 Measurement

81. Result

82. Summary and Prospects

83. Summary of 13 measurements from beams MINOS T2K 13 ~7 (NH) 13 ~9 (IH) 13 ~9 (NH) 13 ~10 (IH) ~2 zero exclusion ~3 zero exclusion

84. Summary of 13 measurements from reactors Daya Bay (June 2012) 13 ~8.7 (~8 zero exclusion) RENO (June 2012) 13 ~9.8 (~6 zero exclusion) Double Chooz 13 ~9.6 (~3 zero exclusion)

85. Summary of 13 measurements Global fit from Daya Bay, RENO, Double Chooz and T2K: 1 2 3 4 N Fogli, Lisi, Marrone, Montanino, Palazzo, Rotunno: hep-ph/1205.5254 (2012) Sin 2 13 = 0.0241 ± 0.0025 (NH) Sin 2 13 = 0.0244 ± 0.0025 (IH) 13 = 8.9 ± 0.9 (~10% relative uncertainty)

86. Energy Spectra Spectral shape contains some potentially peculiar features when compared to expectation. Double Chooz RENO Daya Bay sin 2 (2 13 )=0.12 m 2 atm = 3.0 10 -3 eV 2 Far/Near ratio simulated

87. Summary and Prospects Better understanding of spectral shape: hint of new physics?!? 13 measured to be non zero with > 7 C.L. and 10% uncertainty In the next 3 years expected to be known with 5% uncertainty Going from the unknown to the best measured neutrino mixing angle: 2003-2012!