1. Recent Results from the T2K ND280 detector Jonathan Perkin on behalf of the T2K collaboration KAMIOKA TOKAI 295 km

2. Recent results from the T2K ND280 Detector Jonathan PerkinPANIC 20142 ND280 INGRID Super-Kamiokande Near Detectors The T2K Experiment Tokai to Kamioka  ➝ e  ➝  ~500 Collaborators 59 Institutions 11 Countries ➝ -

3. Recent results from the T2K ND280 Detector T2K Analysis Concept  ➝ x oscillation measurement initially a counting experiment – how many of each flavour detected? parameters also extracted from reconstructed energy spectrum 1. measure source flux at near detector 2. extrapolate flux to far detector and predict observed rate 3. measure  deficit (disappearance) or e excess (appearance) 4. use deficit/excess to exclude null oscillation hypothesis Sounds simple, but… many inputs required many sources of uncertainty many correlations to consider several independent analyses Jonathan PerkinPANIC 20143

4. Recent results from the T2K ND280 Detector Dominated by Charged Current Quasi Elastic (M A QE ) Resonant CC pion (M A Res ) Deep Inelastic Scattering T2K Physics :  + n(p) @ 0.1-2GeV  ➝ e appearance and  ➝  disappearance Jonathan PerkinPANIC 20144 n p W+W+ l l-l- Formaggio & Zeller, Rev. Mod. Phys. 84 (2012) p p W+W+ l l-l- ++  ++ N W+W+ l l-l-  ±,  0,N’ Near detectors constrain cross section and flux prior to oscillation

5. Recent results from the T2K ND280 Detector Jonathan PerkinPANIC 20145 280m from target 2.5° from beam axis Upstream π 0 detector (P0D) scintillator interleaved with C and H 2 O targets and scintillator/brass in ECal PODules 2x 0.8ton Fine Grained Detectors (FGD) scintillator interleaved with C (FGD1) and H 2 O (FGD2) target 3x Time Projection Chambers (TPC) for accurate dE/dx based PID Electromagnetic Calorimeters (ECAL) hermetic lead/scintillator Side-Muon Range Detector (SMRD) scintillator paddles interleaved with magnet flux return 0.2T magnetic field refurbished UA1/NOMAD magnet Near Detector @ 280m 2.5° BEAM SMRD

6. Recent results from the T2K ND280 Detector Jonathan PerkinPANIC 20146 280m from target 2.5° from beam axis Upstream π 0 detector (P0D) scintillator interleaved with C and H 2 O targets and scintillator/brass in ECal PODules 2x 0.8ton Fine Grained Detectors (FGD) scintillator interleaved with C (FGD1) and H 2 O (FGD2) target 3x Time Projection Chambers (TPC) for accurate dE/dx based PID Electromagnetic Calorimeters (ECAL) hermetic lead/scintillator Side-Muon Range Detector (SMRD) scintillator paddles interleaved with magnet flux return 0.2T magnetic field refurbished UA1/NOMAD magnet Near Detector @ 280m 2.5° BEAM SMRD

7. Recent results from the T2K ND280 Detector Jonathan PerkinPANIC 20147 280m from target 2.5° from beam axis Upstream π 0 detector (P0D) scintillator interleaved with C and H 2 O targets and scintillator/brass in ECal PODules 2x 0.8ton Fine Grained Detectors (FGD) scintillator interleaved with C (FGD1) and H 2 O (FGD2) target 3x Time Projection Chambers (TPC) for accurate dE/dx based PID Electromagnetic Calorimeters (ECAL) hermetic lead/scintillator Side-Muon Range Detector (SMRD) scintillator paddles interleaved with magnet flux return 0.2T magnetic field refurbished UA1/NOMAD magnet Near Detector @ 280m 2.5° BEAM SMRD

8. Recent results from the T2K ND280 Detector The ND280 TPC Jonathan PerkinPANIC 20148 positively charged TPC tracks negatively charged TPC tracks TPC dE/dx TPC electron likelihood for e ± and  Excellent electron/muon separation from ND280

9. Recent results from the T2K ND280 Detector ND280  candidate event Jonathan PerkinPANIC 20149 ND280 e candidate event Charged Current  in FGD1 no accompanying pions muon-like TPC PID ECal track Charged Current e  in FGD2 no accompanying pions electron-like TPC PID ECal shower FGD1 TPC2 FGD2 TPC3 ECal ECal FGD1 TPC2 FGD2 TPC3 ECal ECal μ-μ- e-e-

10. Recent results from the T2K ND280 Detector On Axis Near Detector Interactive Neutrino Grid (INGRID) 280m from target on beam axis 16x iron/scintillator tracking calorimeters 1x all-scintillator proton module monitors beam centre, profile and CC inc rate INGRID measurements: CC inclusive on Fe, C and Fe/CH [arXiv:1407.4256v1[arXiv:1407.4256v1] coherent CCπ on C CCQE on CH differential cross sections Jonathan PerkinPANIC 201410

11. Recent results from the T2K ND280 Detector Charged Current Event Classifications The CC sample is separated into 3 classifications defined by number of reconstructed pions from final state interactions (FSI) CC0  =  no charged or neutral FSI pions CC   =  exactly 1 +ve FSI pion (no –ve or neutral) CCOther= all other combinations of FSI pions (one or more –ve or neutral, >1 +ve) This allows for topology dependent systematics featuring different combinations of sub-detector response Improves overall cross section + flux uncertainties Jonathan PerkinPANIC 201411 CC0  CC1   CCOther FGD TPC μ-μ- μ-μ- π+π+ μ-μ-

12. Recent results from the T2K ND280 Detector The Near Detector Constraint Jonathan PerkinPANIC 201412 Neutrino Flux Model: Data-driven: External (NA61/SHINE + others), beam monitor measurements [priors] Uncertainties: modeled by variation of normalization parameters (b) in bins of neutrino energy and flavour

13. Recent results from the T2K ND280 Detector The Near Detector Constraint Jonathan PerkinPANIC 201413 Neutrino Cross Section Model (NEUT): Data-driven: External neutrino, electron and pion scattering data [priors] Uncertainties: modeled by variations of model parameters – axial mass (M A ), Fermi-momentum (p F ), binding energy (E b ), ad-hoc parameters (shape and normalization) Neutrino Flux Model: Data-driven: External (NA61/SHINE + others), beam monitor measurements [priors] Uncertainties: modeled by variation of normalization parameters (b) in bins of neutrino energy and flavour

14. Recent results from the T2K ND280 Detector The Near Detector Constraint Jonathan PerkinPANIC 201414 Neutrino Cross Section Model (NEUT): Data-driven: External neutrino, electron and pion scattering data [priors] Uncertainties: modeled by variations of model parameters – axial mass (M A ), Fermi-momentum (p F ), binding energy (E b ), ad-hoc parameters (shape and normalization) Constraint from ND280 Data: Data Samples enhanced in CC interactions with 0, 1 or N pions Fit to data constrains flux, b, and cross section, x=(M A, p F, E b, ad-hoc, etc.), parameters Constrained SK flux parameters and subset of cross section parameters are used to predict SK event rates Neutrino Flux Model: Data-driven: External (NA61/SHINE + others), beam monitor measurements [priors] Uncertainties: modeled by variation of normalization parameters (b) in bins of neutrino energy and flavour

15. Recent results from the T2K ND280 Detector CC0  Jonathan PerkinPANIC 201415 CC1   CCother Near Detector Constraint (p, θ) μ distributions measured for each classification cross section and flux parameters floated to find best fit far detector MC reweighted to fit results of near detector measurements for each classification

16. Recent results from the T2K ND280 Detector 2013 Near Detector Constraint 2013 analysis with CC0π, CC1π + and CCOther classifications reduces parameter uncertainties Jonathan PerkinPANIC 201416 cross section parameters and uncertainties oscillation parameter uncertainties

17. Recent results from the T2K ND280 Detector 2014 Near Detector Constraint 2014 electron neutrino appearance flux and cross section parameter uncertainties uncertainty (RMS/mean in %) on predicted number of far detector ν e events Jonathan PerkinPANIC 201417

18. Recent results from the T2K ND280 Detector 2014 Near Detector Constraint Jonathan PerkinPANIC 201418 Effect of near detector constraint on reconstructed neutrino energy at far detector disappearance channelappearance channel expected n o. of ν μ events expected n o. of ν e events ν μ ν e

19. Recent results from the T2K ND280 Detector Measuring Intrinsic e Component of Beam Irreducible e contamination due to muon and kaon decays Important background for e appearance affects predicted rate at far detector split into CCQE-like and CCnonQE-like samples CCQE-like e event with electron like TPC track + ECal shower Jonathan PerkinPANIC 201419 PHYSICAL REVIEW D 89, 092003 (2014)

20. Recent results from the T2K ND280 Detector Measuring Intrinsic e Component of Beam Reconstructed electron momentum for CCQE-like sample Expect 1.2% e component (from MC) N e meas / N e MC = 1.01 ± 0.10 Constrain using in-situ e ± control samples Jonathan PerkinPANIC 201420 PHYSICAL REVIEW D 89, 092003 (2014)

21. Recent results from the T2K ND280 Detector ND280 Cross Section Measurements Cross-section uncertainties are a large source of error narrow band beam provides access to cross sections at ~1GeV measurable at ND280 little existing experimental data Several different targets in ND280 Hydrocarbons CH(scintillator) Water H 2 O(target masses) Metals Fe,Pb,brass(calorimetric absorbers) Jonathan PerkinPANIC 201421 [1] : see slide 13

22. Recent results from the T2K ND280 Detector ND280 Cross Section Measurements Cross-section uncertainties are a large source of error narrow band beam provides access to cross sections at ~1GeV measurable at ND280 little existing experimental data Several different targets in ND280 Hydrocarbons CH(scintillator) Water H 2 O(target masses) Metals Fe,Pb,brass(calorimetric absorbers) Jonathan PerkinPANIC 201422 [1] : see slide 13 cancellations between near and far detectors

23. Recent results from the T2K ND280 Detector ND280 Cross Section Measurements Cross-section uncertainties are a large source of error narrow band beam provides access to cross sections at ~1GeV measurable at ND280 little existing experimental data Several different targets in ND280 Hydrocarbons CH(scintillator) Water H 2 O(target masses) Metals Fe,Pb,brass(calorimetric absorbers) Jonathan PerkinPANIC 201423 [1] : see slide 13 no cancellations between near and far detectors

24. Recent results from the T2K ND280 Detector ND280 Cross Section Measurements ~1GeV measurement of differential CC inc  on Carbon total flux averaged: σφ = 6.91 ± 0.13 (stat) ± 0.84 (syst)×10 −39 cm 2 /nucleon Jonathan PerkinPANIC 201424 Phys. Rev. D 87, 092003 (2013)

25. Recent results from the T2K ND280 Detector ND280 Cross Section Measurements ~1GeV measurement of differential CC inc e on Carbon total flux averaged: σφ = 1.11 ± 0.09 (stat) ± 0.18 (syst) × 10 −38 cm 2 /nucleon Jonathan PerkinPANIC 201425 arXiv:1407.7389

26. Recent results from the T2K ND280 Detector ND280 anti-neutrino events in 2014 +ve muon in FG2-TPC3 and downstream ECal Jonathan PerkinPANIC 201426 μ+μ+ FGD2 TPC3 ECal

27. Recent results from the T2K ND280 Detector Summary To date, T2K has recorded 6.9x10 20 POT of neutrino-mode data 6.57x10 20 POT analysed 8% of design goal First anti-neutrino mode data acquired in 2014 0.5x10 20 POT acquired ND280 measurements constrain the neutrino cross section and flux parameters resulting in a reduction of predicted event rate uncertainties ND280 cross section measurements feedback into MC CC inclusive flux integrated measurements for ν μ and ν e differential measurements coming soon Jonathan PerkinPANIC 201427

28. Recent results from the T2K ND280 Detector Jonathan PerkinPANIC 201428 Thank You!

29. Recent results from the T2K ND280 Detector Backup Slides Jonathan PerkinPANIC 201429

30. Recent results from the T2K ND280 Detector Recorded protons on target (POT): 6.9x10 20 nu mode, 0.51x10 20 anti-nu mode <1mrad (~16MeV [2%]) beam stability for total period ~8% of design goal POT so far J-PARC Beam Jonathan PerkinPANIC 201430 I : 50kW II : 145kW III : 190kW IV : 235kW V : 235kW

31. Recent results from the T2K ND280 Detector T2K analysis strategy Jonathan PerkinPANIC 201431

32. Recent results from the T2K ND280 Detector Beam Stability (ND280) Jonathan PerkinPANIC 201432

33. Recent results from the T2K ND280 Detector Charged Current ν e Selection CC selection efficiency as a function of true neutrino energy Jonathan PerkinPANIC 201433