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

Hyper-K

David Hadley, University of Warwick

Outline

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

Kamiokande Detectors

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Kamiokande 680 tonne fiducial mass

(1983)

Kamiokande Detectors

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Kamiokande 680 tonne fiducial mass Super-Kamiokande 22.5kt fiducial mass (33x Kamiokande)

(1983) (1996)

Kamiokande Detectors

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Kamiokande 680 tonne fiducial mass Super-Kamiokande 22.5kt fiducial mass (33x Kamiokande)

(1983) (2026?) (1996)

Hyper-Kamiokande 187 kt fiducial mass per tank

Hyper-K Collaboration

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Growing international collaboration: 14 countries, ~300 people

Physics at Hyper-K

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Supernova Accelerator Atmospheric Solar

Neutrinos Proton Decay

Broad physics programme.

Water Cherenkov Technique

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Muon

Water Cherenkov Technique

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Muon

Electron

Water Cherenkov Technique

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Muon Electron

Neutral Pion

Water Cherenkov Technique

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Muon Electron π0

Likelihood

• 1000 -800 -600 -400 -200

200 400 600 800 1000 Count 10 20 30 40 50 60 70 80 90 100

μ e

Excellent PID performance Accelerator νe background is dominated by irreducible intrinsic νe.

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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

Why Water Cherenkov?

Tank Design

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

Tank Design

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

Detector Site

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Photo Sensors

High QE/CE PMT Super-K PMT High QE/CE Hybrid PD

Venetian blind dynode Box and Line dynode Avalanche diode

QE 22% CE 80% QE 30% CE 93% QE 30% CE 95%

Photo Sensors

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

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Photo Sensors

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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

Worldwide R&D

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Lots of Physics with Hyper-K

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Proton Decay Mass hierarchy with atm. O(105) events from typical Supernova @ 10 kpc SRN

Neutrino Oscillations

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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 θij, δCP + higher order terms involving δCP Appearance probability: Relative phase difference between due to mass difference, Δm2

Neutrino Oscillations

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

Neutrino Oscillations

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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

Neutrino Oscillations

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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

T2K / Hyper-K Flux

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(GeV)

ν

E

1 2 3

(A.U.)

295km

µ

ν

Φ

0.5 1

° OA 0.0 ° OA 2.0 ° OA 2.5

1 2 3

Narrow band beam off-axis Flavour composition nu-mode: ~94% νμ anti-nu mode: ~92% ν̅μ

(for E < 1.25 GeV)

Neutrino Energy Measurement

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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

What we actually measure:

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• Energy (GeV)

0.5 1 1.5 2 2.5 3 3.5

Events

5 10 15 20 25 30 35

Unoscillated prediction

1R =0.5)

• 2

Oscillated prediction (sin

1R Data events

1R

• Energy (GeV)

0.2 0.4 0.6 0.8 1 1.2

Events

1 2 3 4 5 6 7 8

Unoscillated prediction

1R =0.0251)

• 2

Oscillated prediction (sin

1R Data events

1R

• νe appearance

νμ disappearance

θ23 : dip amplitude Δm322 : dip energy

Measurement precision limited by:

• Statistics
• Neutrino energy reconstruction
• Knowledge of unoscillated spectrum

and background contamination

θ13, δCP, mass hierarchy: peak amplitude

Reconstructed Reconstructed

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Accelerator based Neutrino Oscillation Experiments

Current LBL Future LBL

Super‐Kamiokande J‐PARC Near Detectors

Neutrino Beam 295 km

• Mt. Noguchi‐Goro

2,924 m

• Mt. Ikeno‐Yama

1,360 m

1,700 m below sea level

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Near Detectors (ND280+INGRID) Far Detector (Super-K)

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2013: νe appearance established effect is large, opens the way to leptonic CP violation δCP.

28 events observed (4.3 expected background)

• Phys. Rev. Lett. 112, 061802 (2014)

2017: “indications” of CP violation

T2K νe appearance

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2013: νe appearance established effect is large, opens the way to leptonic CP violation δCP.

28 events observed (4.3 expected background)

• Phys. Rev. Lett. 112, 061802 (2014)

Small νe excess and ν̅e deficit Current measurement based on 74+7 events in single ring sample 2017: “indications” of CP violation

T2K νe appearance

First Indications of CP violation

32 )

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θ (

2

sin

15 20 25 30 35

3 −

10 ×

(Radians)

CP

δ

3 − 2 − 1 − 1 2 3

Normal - 68CL Normal - 90CL Inverted - 68CL Inverted - 90CL Best fit

T2K Run1-8 Preliminary

)

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θ (

2

sin

10 15 20 25 30 35 40 45 50

3 −

10 ×

(Radians)

CP

δ

3 − 2 − 1 − 1 2 3

Normal - 68CL Normal - 90CL Inverted - 68CL Inverted - 90CL Best fit PDG 2016

T2K Run1-8 Preliminary

(rad)

CP

δ

3 − 2 − 1 − 1 2 3

ln(L) ∆

• 2

5 10 15 20 25 30 Normal Inverted T2K Run1-8 Preliminary

CP conserving values excluded at 2σ Statistically limited Dependent on reactor ν̅e disappearance measurement

T2K Projected Sensitivity

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POT

1 2 3 4 5 6 7 8 9 10

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10 ×

2

χ ∆

1 2 3 4 5 6 7 8 9 10

90% C.L. C.L. σ 3

=0.40

23

θ

2

sin =0.50

23

θ

2

sin =0.60

23

θ

2

sin

• Stat. Err. Only

Projected Sys. Errs.

arXiv:1409.7469 [hep-ex]

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θ 2

2

sin

0.00 0.05 0.10 0.15 0.20 0.25

) ° (

CP

δ

• 150
• 100
• 50

50 100 150

NH, no Sys. Err. NH, w/ Sys. Err. IH, no Sys. Err. IH, w/ Sys. Err.

arXiv:1409.7469 [hep-ex]

~2.5σ projected significance if maximal CP violation. to firmly establish CP violation we will need Hyper-K!

T2K-I T2K present

J-PARC Beam Upgrades

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

Hyper-K Projected Sensitivity

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10 years x 1 tank x 1.3 MW νe ~ 2058, ν̅e ~ 1906 events Assuming 3-4% systematic uncertainty (cf T2K present ~6%)

Statistics

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Experiment νe + ν̅e 1/√N Ref. T2K (current) 74 + 7 12% + 40%

2.2×1021 POT

NOvA (current) 33 17%

FERMILAB-PUB-17-065-ND

NOvA (projected) 110 + 50 10% + 14%

arXiv:1409.7469 [hep-ex]

T2K-I (projected) 150 + 50 8% + 14%

7.8×1021 POT, arXiv:1409.7469 [hep- ex]

T2K-II 470 + 130 5% + 9%

20×1021 POT, arXiv1607.08004 [hep- ex]

Hyper-K 2058 + 1906 2% + 2%

10 yrs 1-tank 2017 Design Report TBR

DUNE 1200 + 350 3% + 5%

3.5+3.5 yrs x 40kt @ 1.07 MW arXiv:1512.06148 [physics.ins-det]

Current appearance measurements stats dominate O(103) νe at future experiments → demands ~2% systematics O(104) νμ → need systematics as good as we can get!

T2K Systematic Uncertainties

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Error Source μ sample [%] e sample [%] ν ν̅ ν ν̅ SK Detector 1.9 1.6 3.0 4.2 SK FSI+SI+PN 2.2 2.0 2.9 2.5 ND280 Constraint (Flux + Cross Section) 3.3 2.7 3.2 2.9 σ(νe)/σ(νμ)

• 2.6

1.5 NC 1γ

• 1.1

2.6 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

ND280 constraint 13%→3% Pion Final State Interactions (FSI) and Secondary Interactions (SI) modelling important Theoretical uncertainty νe to νμ Difficult to constrain with near detector

T2K preliminary (final systematics pending)

Total systematic uncertainty ~4 - 6% Smaller than stats. uncertainty (for now!)

Flux Uncertainties

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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)

(GeV)

ν

E

• 1

10 1 10 Fractional Error 0.1 0.2 0.3

µ

ν SK: Neutrino Mode,

Hadron Interactions Proton Beam Profile & Off-axis Angle Horn Current & Field Horn & Target Alignment

Material Modeling Number of Protons 13av2 Error 11bv3.2 Error

, Arb. Norm.

E × Φ

µ

ν SK: Neutrino Mode,

Flux Uncertainties

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Significant reductions from thick/replica target If high power beam requires different target material/geometry new dedicated hadron production measurements will be necessary

Neutrino Energy (GeV)

2 4 6 8 10 12 14 16 18 20

Fractional Uncertainties

0.02 0.04 0.06 0.08 0.1 0.12 0.14

π MIPP NuMI X π → pC KX → pC X π → nC MIPP NuMI K nucleonX → pC nucleon-A target abs. meson inc.

• ther abs.
• thers

total HP

Neutrino Energy (GeV)

2 4 6 8 10 12 14 16 18 20

Fractional Uncertainties

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

meson inc. X π → pC KX → pC target abs. X π → nC nucleonX → pC

• ther abs.

nucleon-A

• thers

total HP

Thin Target Thick Target

MINERvA Low E NuMI Flux Uncertainties, Phys. Rev. D 95, 039903 (2017)

Detector Modelling Uncertainties

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Energy [MeV] ν Rec.

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Number of Events /50MeV

1 2 3 4 5 6 7 8 9

Energy [MeV] ν Rec.

200 400 600 800 1000 1200

Number of Events /50MeV

0.5 1 1.5 2 2.5 3 3.5 4 T2K Preliminary T2K Preliminary

1Rμ 1Re SK detector response evaluated with data-MC comparisons in atmospheric sample May be limited by control sample statistics Possible to move toward bottom-up detector systematic uncertainty

Calibration

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Precise PMT response testing Automated source deployment “Neutristor” Neutron Generator Fake muon source

Scattered Light

Calibration

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Using Super-K 2018 shutdown for direct testing of newly developed calibration systems for Hyper-K R&D for new optical calibration system in progress

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Direct Light

Neutrino Interaction Model Uncertainties

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Wide range of processes need to be simulated Require both lepton and hadronic side of the interaction Nuclear effects important in the relevant energy regime Experiments rely on MC generators for Evisible→ Eν extrapolation Model parameter uncertainties from fits to external datasets Sometimes parameter error must be inflated or ad-hoc parameters to account for discrepancies between model and data or known flaws in the model

T2K Cross-Section Model

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Implemented in NEUT MC generator Quasi-elastic scattering most important process at T2K energies

• Valencia 2p-2h model Phys. Rev. C83 (2011) 045501
• Long-range effects with Random Phase Approximation
• Parameters introduced to vary normalisation and shape
• Relativistic Fermi Gas (RFG) nuclear model
• Uncertainties from RFG ↔ Local Fermi Gas
• Final state interactions with cascade model

No priors on most CCQE parameters Constraint from near detector Impact of alternative models not implemented in oscillation analysis evaluated with fake data studies

Near Detector Development

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Near Detector (ND280) Carbon and Oxygen target materials Acceptance differs from far detector Magnetic field for sign selection

CC 1μ + 0π + X CC 1μ + 1π+ + X CC other

Near Detector Development

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Planned ND280 Near Detector Upgrade

ν beam

Near detector upgrades for T2K-II and T2HK era New target with increased angular acceptance

TPC TPC New target

Near Detector Development

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TPC measurements precisely image ν-nucleus interaction vertex → better constraints on models

Ultra-low thresholds with gaseous TPC

nuPRISM

“Water elevator” Measure ∫σ(E)φ(E)dE as a function of theta [arXiv:1412.3086]

E61 Experiment

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Two competing collaborations Merged into a single collaboration: E61 Experiment TITUS

same off-axis angle far detector Gd, muon range detector [arXiv:1606.08114]

E61 Experiment

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C Vilela, NUFACT2017

Linear combinations of measurements at various

• ff-axis angles

Measure response for an arbitrary flux Reduce dependence on nuclear models

E61 Experiment

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Far detector prediction for

• scillated flux

Pseudo- monochromatic beams

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HK selected in “Master Plan” of Science Council in Japan HK selected as highest-priority large-scale projects MEXT Roadmap 2017 Funding request in progress Construction: 2018, Operation: 2026

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Project Timeline

Summary

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Hyper-K well placed to build on the huge success

• f Super-K experiment

Capable of world leading measurements in neutrino

• scillations, nucleon decay, neutrino astrophysics

Aim to start construction 2018 for operation in 2026

References: T2HKK White Paper, arXiv:1611.06118 [hep-ex] HK Design Report, KEK Preprint 2016-21 HK Physics Sensitivity, PTEP (2015) 053C02

Hyper-K

David Hadley, University of Warwick

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Backup

Physics at Hyper-K

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Proton Decay

Leptonic CP violation

(see following slides)

Mass Hierarchy determination

>3σ

θ23 octant determination

3σ for sin2 θ23 >0.56 or sin2 θ23 < 0.46

p → e+ + π0 >1.3x1035 years 90% CL p → ν + K+ >3.2x1034 years 90% CL Broad physics programme. SN ~200,000 @ 10kPC SN ~30-50 @ M31 200 solar ν per day Indirect dark matter search Supernova Solar Accelerator Atmospheric

Neutrinos

Korean Tank

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Stronger CP effect at the second oscillation maximum A second tank in Korea would be be able to measure this effect

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Near Detector (ND280) Carbon and Oxygen target materials Acceptance differs from far detector Magnetic field for sign selection

CC 1μ + 0π + X CC 1μ + 1π+ + X CC other

Photo Sensors

Time Resolution 1p.e. charge distribution

Multi-p.e. charge distribution

Photo Sensors

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Near Detector Development

New/Upgraded Detectors in the Existing ND280 Complex WAGASHI Water dominated target 4π acceptance Water based liquid scintillator

e.g. High Pressure Gas TPC

An alternative approach is to improve knowledge of neutrino- nucleus interactions

Leptonic CP Violation

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ν

(GeV)

ν rec

Reconstructed Energy E

0.2 0.4 0.6 0.8 1 1.2

Difference of events/50 MeV

• 150
• 100
• 50

50 100 150

sec]

7

Integrated beam power [MW 10

2 4 6 8 10

[degree]

δCP 68% CL error of

5 10 15 20 25 30 35 40 45 50

= 0 δ = 90 δ

sec]

7

Integrated beam power [MW 10

2 4 6 8 10 [%]

δCP Fraction of

10 20 30 40 50 60 70 80 90 100

σ 5 σ 3

Measure δCP by comparing data with beam in ν-mode with anti-ν mode δCP measured to < 20o

• ver entire space

CP violation can be established at 3σ (5σ) for 76% (58%) of δCP space.

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200 μs capture time Eγ = 2.2 MeV Low light yield Close to or below trigger threshold Low detection efficiency (~18%)

Neutrino energy (MeV) 14 16 18 20 22 24 26 28 30 )

• 1

MeV

• 1

s

• 2

flux upper limit (cm

e

ν

• 2

10

• 1

10 1 10

2

10 s) µ T ( ∆ 100 200 300 400 500 600 700 800 s µ Number of events / 10 100 200 300 400 500 600 700 800 900

arXiv:1311.3738 [hep-ex]

SK with n-tag SK w/o n-tag

Neutron Capture on Hydrogen

n + p → d + γ νe + p → e+ + n ̄ e+

p

Initial charged lepton signal

n p

Delayed γ signal γ νe ̄

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20 μs capture time Eγ ~ 8 MeV cascade (~4 MeV visible) Fast capture time (small ΔT window) Higher energy γ signal

Neutron Capture on Gadolinium

νe + p → e+ + n ̄ e+

p

Initial charged lepton signal

n Gd

Delayed γ signal γ νe ̄

arXiv:0811.0735 [hep-ex]

5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10

E = 4.3 ± 0.1 MeV (a) Bar: Data Hatched: MC

Energy [MeV] Number of Events

1 10 10 2 100 200 300 400 500

τ = 21.2 ± 6.1 µs (c) Data

∆T [µs] Number of Delayed Signals

Neutron Capture on Gadolinium

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0.1% Gd fraction gives 90% neutrons captured on Gd. Cross section for neutron capture: Gd (49,700 b), H (0.3 b) 0.1%

0.01% 1% 0.001%

Percentage of Gd by mass in Water Fraction of captures on Gd

Applications: Supernova Relic Neutrinos

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A low energy example Directly observable local supernova are all too rare Alternative is to measure diffuse supernova background DSNB/SRN Very low rate Large backgrounds

100 200 300 400 500 600 700 800 900 10 15 20 25 30 35 40 45 50

Energy (MeV) Events/2MeV/0.56Mton/10years

S R N + B . G . total B.G. inv.mu B.G.

• atmsph. !

– e

spallation B.G.

No neutron tagging

arXiv:1109.3262 [hep-ex]

Applications: Supernova Relic Neutrinos

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A low energy example Directly observable local supernova are all too rare Alternative is to measure diffuse supernova background DSNB/SRN Very low rate Large backgrounds A few clean events per year in SK ~100s per year in HK Removed by requiring coincidence with neutron

20 40 60 80 100 120 140 160 180 200 10 15 20 25 30 35 40 45 50

Energy (MeV) Events/2MeV/0.56Mton/10years

SRN+B.G.(inv.mu 1/5) total B.G. i n v . m u ( 1 / 5 )

• atmsph. !

– e

with neutron tagging

arXiv:1109.3262 [hep-ex]

Tank Parameters

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