Hyper-K David Hadley, University of Warwick Outline Hyper-K - PowerPoint PPT Presentation

Hyper-K David Hadley, University of Warwick

Outline Hyper-K Detector Long baseline neutrino oscillation status and prospects Systematic uncertainty challenges and solutions 2

Kamiokande Detectors Kamiokande 680 tonne fiducial mass (1983) 3

Kamiokande Detectors Super-Kamiokande 22.5kt fiducial mass (33x Kamiokande) Kamiokande (1996) 680 tonne fiducial mass (1983) 4

Kamiokande Detectors Super-Kamiokande 22.5kt fiducial mass (33x Kamiokande) Kamiokande (1996) 680 tonne fiducial mass (1983) Hyper-Kamiokande 187 kt fiducial mass per tank 5 (2026?)

Hyper-K Collaboration Growing international collaboration: 14 countries, ~300 people 6

Physics at Hyper-K Proton Decay Neutrinos Solar Supernova Atmospheric Accelerator Broad physics programme. 7

Water Cherenkov Technique Muon 8

Water Cherenkov Technique Muon Electron 9

Water Cherenkov Technique Muon Electron Neutral Pion 10

Water Cherenkov Technique Muon Electron π 0 100 Count e μ 90 80 Excellent PID performance 70 60 50 Accelerator ν e background 40 is dominated by irreducible 30 intrinsic ν e . 20 10 0 -1000 -800 -600 -400 -200 0 200 400 600 800 1000 Likelihood 11

Why Water Cherenkov? Scalability Water is cheap, non-toxic, liquid at room temperature we already know how to build big water WC detectors Proven technology many years of experience from Super-K low risk Excellent performance based on real Super-K and T2K performance 12

Tank Design Old: Horizontal Egg-shaped Tank New: Optimised Vertical Tank 13

Tank Design ID: 40% photo-coverage 40,000 photo sensors per tank OD: 14

Detector Site 15

Photo Sensors Super-K PMT High QE/CE PMT High QE/CE Hybrid PD QE 22% QE 30% QE 30% CE 80% CE 93% CE 95% Venetian blind Box and Line Avalanche diode dynode dynode

Photo Sensors 2x improvement in photon detection efficiency Better timing and charge resolution 17 17

Photo Sensors SK PMT HQE B&L B HQE B&L A Optimised bulb design High pressure and implosion tests show new PMTs safe for use in HK tank 18

Worldwide R&D 19

Lots of Physics with Hyper-K Mass hierarchy Proton Decay with atm. SRN O(10 5 ) events from typical Supernova @ 10 kpc 20

Neutrino Oscillations Weak flavour eigenstates ≠ Mass eigenstates Neutrinos produced and detected in their weak flavour states Unitary PMNS mixing matrix parameterised with 3 angles and CP violating phase θ ij , δ CP Relative phase difference between due to mass difference, Δ m 2 Appearance probability: + higher order terms involving δ CP 21

Neutrino Oscillations Higgstan [http://higgstan.com/4koma-t2k/] 22

Neutrino Oscillations Typically perform experiment at fixed L with wide range of E CP violation ~ 20% effect at 1st oscillation maximum Much larger effect at 2nd oscillation maximum 23

Neutrino Oscillations Typically perform experiment at fixed L with wide range of E CP violation ~ 20% effect at 1st oscillation maximum Much larger effect at 2nd oscillation maximum 24

T2K / Hyper-K Flux Narrow band beam off-axis Flavour composition 0 1 2 3 1 OA 0.0 ° OA 2.0 ° (A.U.) OA 2.5 ° 295km 0.5 µ ν Φ nu-mode: ~94% ν μ anti-nu mode: ~92% ν̅ μ 0 0 1 2 3 E (GeV) (for E < 1.25 GeV) 25 ν

Neutrino Energy Measurement Protons usually below Cherenkov threshold Neutrons can be counted but no energy measurement For quasi-elastic interactions neutrino energy can be reconstructed from lepton kinematics Background from inelastic scattering where energy is mis-measured Interaction is on bound state Nuclear effects are important 26

What we actually measure: � � � � ν μ disappearance ν e appearance 8 Events Events 1R Unoscillated prediction 1R Unoscillated prediction e µ 2 2 35 1R Oscillated prediction (sin =0.5) 7 � 1R Oscillated prediction (sin � =0.0251) � � e 23 13 µ 1R Data events 1R Data events e µ 30 6 25 5 20 4 θ 13 , δ CP , mass hierarchy: 15 3 peak amplitude θ 23 : dip amplitude 10 2 Δ m 322 : dip energy 5 1 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.2 0.4 0.6 0.8 1 1.2 Energy (GeV) Energy (GeV) Reconstructed Reconstructed Measurement precision limited by: • Statistics • Neutrino energy reconstruction • Knowledge of unoscillated spectrum and background contamination 27

Accelerator based Neutrino Oscillation Experiments Current Future LBL LBL 28

Super‐Kamiokande J‐PARC Near Detectors Mt. Noguchi‐Goro 2,924 m Mt. Ikeno‐Yama 1,360 m 1,700 m below sea level Neutrino Beam 295 km Near Detectors (ND280+INGRID) Far Detector (Super-K) 29

T2K ν e appearance 2013: ν e appearance established 2017: “indications” of CP violation 28 events observed (4.3 expected background) Phys. Rev. Lett. 112, 061802 (2014) effect is large, opens the way to leptonic CP violation δ CP . 30

T2K ν e appearance 2013: ν e appearance established 2017: “indications” of CP violation 28 events observed (4.3 expected background) Phys. Rev. Lett. 112, 061802 (2014) Small ν e excess and ν̅ e deficit effect is large, opens the Current measurement based on way to leptonic CP violation 74+7 events in single ring sample δ CP . 31

First Indications of CP violation T2K Run1-8 Preliminary CP conserving values Final systematics pending 3 Normal - 68CL Best fit Normal - 90CL PDG 2016 Inverted - 68CL excluded at 2 σ 2 Inverted - 90CL (Radians) 1 0 Statistically limited CP 1 − Dependent on reactor ν̅ e δ 2 − disappearance − 3 3 − 10 × 10 15 20 25 30 35 40 45 50 measurement 2 sin ( ) θ 13 T2K Run1-8 Preliminary T2K Run1-8 Preliminary Final systematics pending Final systematics pending 3 Normal - 68CL 30 Normal - 90CL Best fit Inverted - 68CL Normal 2 Inverted - 90CL 25 Inverted (Radians) 1 20 ln(L) 0 ∆ 15 -2 CP − 1 δ 10 2 − 5 3 3 − − 10 × 15 20 25 30 35 0 3 2 1 0 1 2 3 − − − 2 sin ( ) θ 13 (rad) δ 32 CP

T2K Projected Sensitivity arXiv:1409.7469 [hep-ex] arXiv:1409.7469 [hep-ex] 10 2 3 C.L. σ sin =0.40 θ 150 NH, no Sys. Err. 9 23 2 sin =0.50 θ 23 NH, w/ Sys. Err. T2K-I 2 8 sin =0.60 θ 100 23 IH, no Sys. Err. Stat. Err. Only 7 IH, w/ Sys. Err. Projected Sys. Errs. 50 6 ) ° T2K present 2 ( χ 0 5 CP ∆ δ 4 -50 3 90% C.L. -100 2 1 -150 21 10 × 0 0.00 0.05 0.10 0.15 0.20 0.25 0 1 2 3 4 5 6 7 8 9 10 2 sin 2 θ POT 13 ~2.5 σ projected significance if maximal CP violation . to firmly establish CP violation we will need Hyper-K ! 33

J-PARC Beam Upgrades HK era Current: ~470 kW Short-term: 750 kW after 2018 long shutdown Goal: 1.3 MW operation at HK operation 34

Hyper-K Projected Sensitivity 10 years x 1 tank x 1.3 MW ν e ~ 2058, ν̅ e ~ 1906 events Assuming 3-4% systematic uncertainty (cf T2K present ~6%) 35

Statistics ν e + ν̅ e Experiment 1/ √ N Ref. T2K (current) 74 + 7 12% + 40% 2.2 × 10 21 POT NOvA (current) 33 17% FERMILAB-PUB-17-065-ND NOvA (projected) 110 + 50 10% + 14% arXiv:1409.7469 [hep-ex] 7.8 × 10 21 POT, arXiv:1409.7469 [hep- T2K-I (projected) 150 + 50 8% + 14% ex] 20 × 10 21 POT, arXiv1607.08004 [hep- T2K-II 470 + 130 5% + 9% ex] 10 yrs 1-tank Hyper-K 2058 + 1906 2% + 2% 2017 Design Report TBR 3.5+3.5 yrs x 40kt @ 1.07 MW DUNE 1200 + 350 3% + 5% arXiv:1512.06148 [physics.ins-det] Current appearance measurements stats dominate O(10 3 ) ν e at future experiments → demands ~2% systematics O(10 4 ) ν μ → need systematics as good as we can get! 36

T2K Systematic Uncertainties ND280 constraint 13% → 3% μ sample [%] e sample [%] Error Source ν ν̅ ν ν̅ SK Detector 1.9 1.6 3.0 4.2 Pion Final State SK FSI+SI+PN 2.2 2.0 2.9 2.5 ND280 Constraint Interactions (FSI) and 3.3 2.7 3.2 2.9 (Flux + Cross Section) Secondary Interactions σ ( ν e )/ σ ( ν μ ) - - 2.6 1.5 NC 1 γ - - 1.1 2.6 (SI) modelling important NC other 0.3 0.1 0.1 0.3 Total Systematic 4.4 3.8 6.3 6.4 Statistical 6.5 12 12 40 Theoretical uncertainty T2K preliminary (final systematics pending) ν e to ν μ Total systematic uncertainty Difficult to constrain with ~4 - 6% near detector Smaller than stats. uncertainty (for now!) 37

Flux Uncertainties SK: Neutrino Mode, SK: Neutrino Mode, ν ν µ µ Fractional Error Hadron Interactions Material Modeling 0.3 Proton Beam Profile & Off-axis Angle Number of Protons Horn Current & Field 13av2 Error Horn & Target Alignment 11bv3.2 Error Φ × E , Arb. Norm. ν 0.2 0.1 0 -1 10 1 10 E (GeV) ν T2K ~ 8-12% (based on thin target tuning) Dominated by hadron interaction modelling Alignment/focussing uncertainties are also important (especially for near to far extrapolation) 38