1. NNN 2011: The d Experiment Joshua Albert Duke University For the T2K Collaboration November 8, 2011

2. Joshua Albert 2 In neutrino interactions, we measure weak (flavor) states (e,μ,τ) which are superpositions of the 3 mass states. Measure oscillation from ν µ beam: NNN 2011 November 8, 2011 Neutrino Oscillation Review Normal hierarchy eigenstate fractions Atmospheric Oscillations Solar OscillationsNon-zero? FlavorMass 1st order oscillation equations +...

3. Joshua Albert 3 NNN 2011 November 8, 2011 T2K Overview 12 countries, 59 institutions, ~500 members ←ν µ Sea of Japan Pacific Ocean 30 GeV p + Plan: 8.33x10 21 POT

4. Joshua Albert 4 NNN 2011 November 8, 2011 Neutrino Beam (pt. 1) Pulsed beam of 30 GeV protons from J-PARC accelerator Slam into graphite target, Make pions (and other particles) p + p → p + π + +... p Target is placed inside 1st magnetic horn... practice describing other stuff

5. Joshua Albert 5 NNN 2011 November 8, 2011 Neutrino Beam (pt. 2) π+π+ µ+µ+ νµνµ π + lifetime: 2.6x10 -8 s µ + lifetime: 2.2x10 -6 s These neutrinos go on to be detected at near and far detectors Pion p-θ distribution tuned from NA61 Data decay volume length: ~96m

6. Joshua Albert 6 NNN 2011 November 8, 2011 Off-axis Neutrino Beam 2-body decay → exact kinematics P(ν µ →ν µ ) P(ν µ →ν e ) Search For: How ν µ spectrum changes (measure θ 23 and ∆m 2 23 ) How much ν e appears (measure θ 13 ) p π (GeV) 2046810 E ν (GeV) 0 0.5 1.0 1.5 2.0 2.5 ∠ 2.5° SK ND Off-axis J- PARC ND On-axis OA2.5° Flux x Cross Section E ν (GeV) optimized! OA2.5° P(µ→µ) P(µ→e)

7. Joshua Albert 7 NNN 2011 November 8, 2011 Near Detectors (280m from target) Scintillator Planes Iron Plates Veto Planes ND280 Off-Axis INGRID Measure direction and stability On-axis

8. Joshua Albert 8 NNN 2011 November 8, 2011 Near Detectors: ND280 Off-Axis Magnetized Detector for beam composition, cross sections, and normalization. Tracker region counts ν µ charged current (CC) events for normalization in the current analyses Scale SK prediction by ND data/MC

9. Joshua Albert 9 NNN 2011 November 8, 2011 Super-Kamiokande 50,000 ton water Cherenkov detector 11,146 PMTs in ID, 1,885 in OD ~1km underground in Mt. Ikenoyama (neutral) ν (charged) µ Cherenkov ring 22.5 kton fiducial volume T2K Data

10. Joshua Albert 10 NNN 2011 November 8, 2011 SK Reconstruction Find vertex (mostly timing) Count rings Find momenta PID from ring topology (“fuzziness”) Use atmospheric data vs. MC to check reconstruction and set systematic errors go quick, don’t describe each step T2K Data

11. Joshua Albert 11 NNN 2011 November 8, 2011 Neutrino Beam Total of 1.43x10 20 POT delivered, less than 2% of final design goal Improvements from Run 1 → Run 2: added 2 bunches, more protons/bunch, increased repetition rate. Reached 145kW beam power before earthquake shut down beam. Run 1 Run 2

12. Joshua Albert 12 T2K beam trigger from beam extraction “Commonview” GPS mode used At SK, 2 GPS units and a Rubidium clock are used to measure and confirm the time stability. NNN 2011 November 8, 2011 Beam Trigger/Timing SK event times absolute time fitted FC events vs. trigger time all SK events Is that just at SK, or J-PARC as well?

13. Joshua Albert 13 NNN 2011 November 8, 2011 Signal at SK Charged Current Quasi-Elastic Events Only single lepton ring visible at SK Ring topology indicates ν e vs. ν µ Incident neutrino energy can be reconstructed (only for CCQE)! Product proton usually below threshold at T2K beam energy. T2K Data

14. Joshua Albert 14 NNN 2011 November 8, 2011 ν e Appearance Backgrounds 1) Beam ν e : ν µ beam only ~99% pure in signal region 2) flavor mis-ID: mostly from ν µ +p →π 0 +ν µ +p d →γ + (γ) NC π 0 Asymmetric Decay e-like ring most likely 2nd ring γs either overlap, or one is faint Total Background: 1.5 events (23% sys. error) SK atmospheric MC

15. Joshua Albert 15 NNN 2011 November 8, 2011 FC FV Selection vs. trigger time all SK events Fully Contained Fiducial Volume Single Ring µ-like p µ > 200 MeV N decay < 2 Data: 88 Events

16. Joshua Albert 16 NNN 2011 November 8, 2011 ν µ Disappearance Analysis Shows power of off-axis technique at 90% CL sin 2 2θ 23 > 0.85 2.1x10 -3 < ∆m 2 23 (eV) < 3.1x10 -3 Fully Contained Fiducial Volume Single Ring µ-like p µ > 200 MeV N decay < 2 Data: 31 Events Consistent with previous experiments

17. Joshua Albert 17 NNN 2011 November 8, 2011 ν e Appearance Fully Contained Fiducial Volume Single Ring e-like E visible >100 MeV N decay = 0 m π < 105 MeV E ν rec <1250 MeV Data: 6 Events... reject low-E backgrounds reject events with muons or pions e-likeµ-like invariant mass with best 2nd ring candidate Point out the pink!!

18. Joshua Albert 18 NNN 2011 November 8, 2011 ν e Appearance Selections Fully Contained Fiducial Volume Single Ring e-like E visible >100 MeV N decay = 0 m π < 105 MeV E ν rec <1250 MeV 6 Events Remain!! Expected Background: 1.5±0.3 (sys.) Data: 6 Events

19. Joshua Albert 19 NNN 2011 November 8, 2011 Many Supporting Distributions Events distribution over POT p-θ of produced e Beam timing

20. Joshua Albert 20 NNN 2011 November 8, 2011 Vertex Distribution Tests only 0.008 events expected from outside ID in FV MC true vertex outside ID Use MC to test for entering backgrounds

21. Joshua Albert 21 NNN 2011 November 8, 2011 Vertex Distribution Tests Relative to wall Relative to center Fiducial volume boundary SK-IV atm ν data SK-IV atm ν MC T2K-like event selections used Use KS test for distribution consistency with expectation SK atm. data and MC agree well near the FV boundary

22. Joshua Albert 22 NNN 2011 November 8, 2011 What it Means for θ 13SK Cross Section FluxND SK FluxND Systematic Errors 23% Error on Bkg 18% Error on Signal Observed 6 Events, with 1.5±0.3 events background at θ 13 = 0 Combine Poisson distribution+ systematics using toy MC p-value of 0.7% 2.5σ significance N obs PDF for θ 13 = 0 0.7% for 6 or more events

23. Joshua Albert 23 NNN 2011 November 8, 2011 ν e Appearance Results θ 13 = 0 is not in the 90% CL acceptance region. Best fit: sin 2 2θ 13 = 0.11 First non-zero measurement of θ 13 at the 90% CL! Normal (Inverted) Hierarchy: 0.03 (0.04) < sin 2 2θ 13 < 0.28 (0.34)

24. Joshua Albert 24 NNN 2011 November 8, 2011 Conclusions T2K has completed two oscillation analyses based on only 2% of the final beam data goal. The ν µ disappearance measurement of θ 23 and ∆m 2 23 is consistent with MINOS and SK, will soon be competitive. The ν e appearance analysis found 6 candidate events with 1.5±0.3 events expected background. This is a measurement that θ 13 ≠ 0 at 2.5σ significance, first indication of non-zero θ 13 at the 90% CL! Plan to restart beam in December 2011. Expect 1x10 21 POT before Summer 2013, will allow exclusions of θ 13 = 0 to: >5σ if sin 2 2θ 13 = 0.11 >3σ if sin 2 2θ 13 = 0.084 (Fogli global best fit) (T2K best fit)

25. Joshua Albert 25 NNN 2011 November 8, 2011 Thank You!

26. Joshua Albert 26 NNN 2011 November 8, 2011 Supplemental Slides

27. Joshua Albert 27 NNN 2011 November 8, 2011 NA61 pion distributions http://arXiv.org/abs/1102.0983

28. Joshua Albert 28 NNN 2011 November 8, 2011 Tables of errors And osc parameters

29. Joshua Albert 29 NNN 2011 November 8, 2011 Appearance Background Makeup Interaction ModeFinal State ν e CC: 0.8 NC: 0.6 ν µ CC: 0.03 Solar Oscillation: 0.09

30. Joshua Albert 30 NNN 2011 November 8, 2011 Beam contributions from flavor

31. Joshua Albert 31 NNN 2011 November 8, 2011 Flux Uncertainties

32. Joshua Albert 32 NNN 2011 November 8, 2011 Beam contributions from flavor numu anti- numu nue anti- nue error bars are statistical

33. Joshua Albert 33 NNN 2011 November 8, 2011 ν e Appearance Selections Fully Contained Fiducial Volume Single Ring e-like E visible >100 MeV N decay = 0 m π < 105 MeV E ν rec <1250 MeV Data: 6 Events POLfit algorithm: find most likely 2nd ring candidate ? optimized!

34. Joshua Albert 34 NNN 2011 November 8, 2011 ∆m 2 plot + MINOS

35. Joshua Albert 35 NNN 2011 November 8, 2011 Plots w/ sensitivity

36. Joshua Albert 36 NNN 2011 November 8, 2011 T2K Statement on OPERA October 20, 2011 Based on our initial assessment of our capability, at the moment T2K cannot make any definitive statement to verify the OPERA measurement of the speed of the neutrino (the OPERA anomaly). We will assess a possibility to improve our experimental sensitivity for a measurement to cross-check the OPERA anomaly in the future. Such a measurement with an improved system, however, could take a while to achieve.

37. Joshua Albert 37 NNN 2011 November 8, 2011 SK Energy Scale Uncertainty

38. Joshua Albert 38 NNN 2011 November 8, 2011 Vertex Distribution Tests only 0.008 events expected from outside ID in FV MC true vertex outside ID FC cuts only Use MC to test for entering backgrounds

39. Joshua Albert 39 NNN 2011 November 8, 2011 Flux Uncertainty Breakdown From Mark Hartz’s FNAL seminar

40. Joshua Albert 40 NNN 2011 November 8, 2011 Cross Section Uncertainties From Mark Hartz’s FNAL seminar

41. Joshua Albert 41 NNN 2011 November 8, 2011 Cross Section Uncertainties From Mark Hartz’s FNAL seminar

42. Joshua Albert 42 NNN 2011 November 8, 2011 θ 13 = 0 event expectations