T2K and T2K-upgrade
A. K. Ichikawa (Kyoto univ.) for the T2K collaboration th
Today’s slides mostly taken from my talk at “Koichiro Nishikawa Memorial Symposium” held on Sep 27 2019 Koichiro Nishikawa (1949-2018) long-baseline pioneered the neutrino oscillation experiments as the founder of the K2K experiment and the first T2K the spokesperson of experiment. 2 3 appearance as a appearance as e ν
Nishikawa-san’s slide at Now1998 next critical step toward CP next critical step toward CP measurement. the first that time, K2K, At accelerator-based long baseline neutrino oscillation experiment, was running. In 1999, Nishikawa-san & proposed to Totsuka-san measure Oscillations peculiar to the Acc.-based long baseline experiment Interference term ~ ∝ sin 𝛿 for neutrino ~ ∝ sin 𝛿 for antineutrino
ν μ disappearance 2𝜃 00% at right energy
∝ ~cos 𝜃 sin 2𝜃 ~0.09% ∝ ~cos 𝜃 sin 2𝜃 ~95% reactor, T2K ∝ ~sin 𝜃 sin 2𝜃 ~5%
4 J-PARC Neutrino Beam on-axis detector : INGRID Near Detectors 1,700 m below sea level 1,700 m 295 km off-axis detector : off-axis ND280 Mt. Noguchi-Goro 2,924 m /s at T2K Far detector(295km away) @750kW proton beam power) at /s 2 /cm ν T2K Experiment, started 2009 in Super-Kamiokande 50 kt detector Cherenkov Water kt) (Fiducial 22.5 ~1 Mt. Ikeno-Yama 1,360 m Super-Kamiokande 5 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models Evolution from K2K to T2K(-I) 6 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models Evolution from K2K to T2K(-I) 7 Current recently increasing, again Number of collaborators Canada US Japan UK Russia Europe & ~500 members, 68 Institutes, 12 countries
T2K collaboration 44 original articles Ph.D116 theses Total citations of papers adds up to 5,972 Total As of 2018, 8 Collaboration photo taken in 2019 at Paris
9 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → KEK-PS(12 GeV) 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members Evolution from K2K to T2K(-I) 10 correlation matrix → 500 kW → ~500 → 5%, far/near ratio → KEK-PS(12 GeV) 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grained active target with surrounding charge-ID, detectors for Magnet and momentum-ID in PID 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Higher intensity proton accelerator Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members Evolution from K2K to T2K(-I) 11 Pacific Ocean 30 GeV Synchrotron Hadron Material&Life 400 MeV Linac 3 GeV RCS Neutrino towards Kamioka
Japan Proton Accelerator Research Complex
J-PARC Joint project of KEK & Japan Atomic Energy Agency Construction from 2008 2001 to 12 13 primary beamline target superconducting magnet superconducting target station １００ｍ Horn decay volume decay dump Neutrino Beamline Near Detector Muon monitors 13 14 primary beamline target superconducting magnet superconducting target station １００ｍ Horn decay volume decay 0.75 MW for upgradable parts with a few exceptions 3 MW for non-upgradable parts dump Near Detector Neutrino Beamline Designed for Muon monitors 14 Beamtime limited in 2019 and 2020 to prioritize accelerator Data taking status upgrade for higher intensity
total Now, running stably at 496 kW beam power ν-beam̅
ν-beam
Analyzed 1.51×1021 POT 1.65×1021 POT
cf. T2K-I goal : 21 , T2K-II goal : 21 15 7.8×10 POT 20×10 POT correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Off-axis beam 9.3%? Fine-grained active target with surrounding charge-ID, detectors for Magnet and momentum-ID in PID 50% to up efficiency increase by Improved reconstruction, Many experts including theorists in collaboration Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Higher intensity proton accelerator Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) Evolution from K2K to T2K(-I) 16 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Off-axis beam 9.3%? Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) Evolution from K2K to T2K(-I) 17 ° BNL-E889 Proposal Idea in Pseud monochromatic beam utilizing pion decay kinematics angle is 2.5 T2K off-axis more signal, less background
Off-axis beam : intense & narrow-band beam peak energy at oscillation max. (~0.6GeV at L=295km) 18 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → 9.3%? Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis Evolution from K2K to T2K(-I) 19 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → 9.3%? Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis Evolution from K2K to T2K(-I) 20 𝜈 𝜈 measurement constrains SK SK 𝜈 ND C 𝒑
Measurement of p+C interaction at 30 GeV for precise neutrino flux prediction Flux uncertaintynow, 5% at peak energy Flux uncertaintynow, 21 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Evolution from K2K to T2K(-I) 22 surrounding detectors for charge-ID, correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Fine-grainedwith active target 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration PID and momentum-ID in Magnet and momentum-ID in PID Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Evolution from K2K to T2K(-I) 23 which UA1 magnet discover W/Z
off-axis near detector: ND280 24 off-axis near detector : ND280 TPC FGD1 TPC FGD2 TPC TPC FGD2 TPC FGD1 water p FGD2: finely- segmented scintillator bars + vs FGD1: finely- segmented scintillator bars dEdx TPC UA1 magnet 25 Momentum distribution Colors represent interaction types
CC0π anti-neutrino neutrino beam mode beam mode
CC1track CC1
CC multi-track CCother
26 correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Improved reconstruction, efficiency increase by up to 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grained active target with surrounding charge-ID, detectors for Magnet and momentum-ID in PID Evolution from K2K to T2K(-I) 27 correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Improved reconstruction, efficiency increase by up to 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grained active target with surrounding charge-ID, detectors for Magnet and momentum-ID in PID Evolution from K2K to T2K(-I) 28 SK MC event display muon + e γ - + e γ e - - e e γ - + e e - e γ - e
Super-Kamiokande electron 29 20 cm → ↓ 0 background π Dist-Wall and To-Wall cut To-Wall and Dist-Wall → removes 70% more more 70% removes SK Analysis upgrade cm 29 resolution vertex Better precision ID and precision Better simultaneous fit with all information including no-hits → iterative fit with either Q or T Q or fit with either iterative > 2 m Dist-Wall – #decay-e, multi-ring 30%~50% increase in statistics! 30%~50% increase in Partially realized and partially work in progress • optimization Fiducial • Reconstruction •non-CCQE samples Usage of 30 correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Many experts including theorists in collaboration Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grained active target with surrounding charge-ID, detectors for Magnet and momentum-ID in PID 50% to up increase by efficiency Improved reconstruction, Evolution from K2K to T2K(-I) 31 correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Many experts including theorists in collaboration Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grained active target with surrounding charge-ID, detectors for Magnet and momentum-ID in PID 50% to up increase by efficiency Improved reconstruction, Evolution from K2K to T2K(-I) 32 Neutrino and hadron interaction model improvement
• Neutrino interaction working group in T2K Many experts including theorists in collaboration • Nuclear model – Global Relativistic Fermi Gas model → Local Fermi Gas, Spectral Function – Correlations between nucleons 12C Spectral function • pion production model • second-class currents and
radiation correction for interaction • Less model dependent analysis
33 M.V.Ivanov et al., J.Phys.Conf.Ser. 1023 (2018) no.1, 012028 correlation matrix → 500 kW → ~500 → 5%, far/near ratio → Larger and More international collaboration Higher intensity proton accelerator and neutrino beamline Narrower neutrino energy beam More reliable neutrino flux prediction Near detector Significant analysis improvement on Super-K Neutrino and hadronic interaction models ~220 members 10kW KEK-PS(12 GeV) beam Off-axis 9.3%? Fine-grained active target with surrounding charge-ID, detectors for Magnet and momentum-ID in PID 50% to up increase by efficiency Improved reconstruction, Many experts including theorists in collaboration Evolution from K2K to T2K(-I) 34 disappearance ̅ 𝜈 significance σ significance by reactor significance σ σ 𝜃 sin 2 candidate event e ν appearance
e
ν Example of 2012 Daya Bay observed non-zero T2K observed 28 events over 4.9bkgs 7.3 2013 w/ >5 Also first confirmation of ‘appearance’ 2011 T2K observed 6 events(1.5 bkgs). 2.5 T2K observed 6 events(1.5 bkgs). 2011 35 And Now, 36 muon antineutrino disappearance
Disappearance muon neutrino disappearance 37 More electron neutrino Less electron antineutrino Tendency,
Appearance 38 T2K
2
, Δm 39 )
CP region 𝑪𝑷 σ (95%) region σ is outside 3 CP-conserving case ( (arXiv:1910.03887) CP-violation phase δ is out side 2 𝜃 w/ reactor constraint reactor σ 3 constraint 68% 68% C.L. w/o reactor 𝜃 40
): 11.1% ): 88.9% vs Normal order ( Inverted order (
Mass Ordering • sensitivity to mass ordering Some by the matter effect • probability (Run1-9) Posterior 41 T2K-II sensitivity stat.only improved sys. 2016 sys. NO , 𝟓 . 𝟎 𝟐𝟑 𝟐 𝐬𝐢𝐧 𝜽 , 𝟐 𝝅 𝑪𝑷 𝜹 T2K-I now
Evolution from T2K-I to T2K-II- CPV sensitivity 42
→ Aim 1.3 MW by upgrading main ring accelerator and the neutrino beamline. increase by Further ~7% horn current 250 kA 320 kA J-PARC PAC PAC J-PARC th
Evolution from T2K-I to T2K-II- Intensity upgrade - N. Saito, Director of J-PARC Center, at 27 Center, N. Saito, Director of J-PARC 43 Overview of T2K analysis
Oscillation Parameter
ND280 detector model hadron interaction model
SK detector model hadron interaction model
𝜋, 𝑝 A data
neutrino flux proton beam ν-nucleus interaction model p-A hadron production nuclear model hadron final state interaction
𝑝/𝜇/𝜈 monitor p-A data e A data ν A data 44 Overview of T2K analysis numbers: error on event rate prediction Oscillation Parameter
ND280 detector model 2% hadron interaction model 8% 4%
SK detector model hadron interaction model 9% 15% 𝜋, 𝑝 A data
neutrino flux proton beam ν-nucleus interaction model p-A hadron production nuclear model hadron final state interaction
𝑝/𝜇/𝜈 monitor p-A data e A data ν A data 45 Improvements expected in 2019 T2K+NOvA and T2K+SK analysis is being discussed Oscillation Parameter btw. collaborations ND280 detector error evaluation detector model 2% with T2K interaction hadron interaction model 8% model4% (cancelation of errors expected) wider angle coverage SK improved tracking and PID detector model different off-axis measurement hadron interaction model 9% 15% 𝜋, 𝑝 A data
neutrino flux new data (by T2K proton beam ν-nucleus interaction modelcollaborators) p-A hadron production nuclear model hadron finalMajor state update interaction of model reduce to 5% by using • Global Fermi Gas model →Spectral replica target data of p-A Function model 𝑝NA61/SHINE/𝜇/𝜈 monitor hadron • binding energy will be re-defined e A data production measurementdata • resonantν Aanddata coherent pion prod 46 ND280 Super-K muon neutrino
CC0π neutrino beam mode
antineutrino CC1track beam mode
47
. . 𝜙 𝜙 baby MIND Iron magnet spectrometer Wagasci modules
Evolution from T2K-I to T2K-II -Wagasci/baby MIND - Near Detector upgrade, measurement at different off-axis measurement at Data taking has started in this November. 48 vertex • larger phase space Cover • higher graduality around improve the understanding To of the neutrino-nucleus interaction be installed in 2021 To
Evolution from T2K-I to T2K-II - Near Detector upgrade, ND280- 49 Backup method invented by Japanese group
Assembling of Super-FGD Adopted method : Fishing line Adopted method : mehodeRussian group invented by 50 Improvements expected after 2021 T2K+NOvA and T2K+SK analysis is being discussed Oscillation Parameter btw. collaborations. ND280 detector error evaluation detector model 2% with T2K interaction hadron interaction model 8% model4% (cancelation of errors expected.) wider angle coverage SK improved tracking and PID detector model different off-axis measurement hadron interaction model More wider angle coverage9% improved tracking and PID 15% 𝜋, 𝑝 A data by upgraded ND280 Neutron tagging by SK-Gd neutrino flux new data (by T2K proton beam ν-nucleus interaction modelcollaborators) p-A hadron production nuclear model hadron finalMajor state update interaction of model reduce to 5% by using • Global Fermi Gas model →Spectral replica target data of p-A Function model 𝑝NA61/SHINE/𝜇/𝜈 monitor hadron • binding energy will be re-defined. e A data production measurementdata • resonantν Aand data coherent pion prod. 51 T2K-II sensitivity stat.only improved sys. 2016 sys.
NO , 𝟓 . 𝟎 𝟐𝟑 𝟐 𝐬𝐢𝐧 𝜽 , 𝟐 𝝅 𝑪𝑷 𝜹 T2K-I result now ☆ 2018
CPV, where are we now? 52 ): 11.1% 0.979] (IH) − T2HK → 1.799, − T2K (95%) region → σ sensitivity to CPV if is ~maximal σ 0.628] (NO) [ − ) is outside 2 POT with 3 POT 3.966, − region 22 𝑪𝑷 σ ): 88.9% vs. Inverted ( is outside 3 confidence interval[
Summary σ 2 CP CP 2020 Super-Kamiokande upgrade by dissolving Gd to 0.01% concentration 2021 Upgrade of beam intensity(750 kW) & ND280 2023~2025 Second beam upgrade to reach 1.3 MW Aiming to collect 1~2x 10 Normal ( CP-conserving case ( CP-conserving case δ Timeline from now Timeline The accelerator-based neutrino oscillation program in Japan, founded by Koichiro Nishikawa, is continuing evolution K2K 53