The Hyper-Kamiokande Experiment

Francesca Di Lodovico Queen Mary University of London

On behalf of the Hyper-K collaboration

NEUTRINO 2016, Royal Geographical Society July 6, 2016 A Multi-purpose Experiment Comprehensive study of  oscillation • CPV Supernova • Mass hierarchy with beam+atmosph.  • 23 octant • Test of exotic scenarios

Nucleon decay discovery potential Sun • All visible modes including p → 푒+ 0 + Accelerator and p→휈 퐾 can be advanced beyond (J-PARC) SK. • Reaching 1035yrs sensitivity

Unique Astrophysics T2HK • Precision measurement of solar  • High statistics Supernova  with pointing capability and energy info. • Supernova relic  (non-burst  ) Proton observation is also possible decay Earth core's chemical composition Etc. The Hyper-Kamiokande Experiment 2 Inaugural Symposium of the HK proto- collaboration@Kashiwa, Jan-2015

12 countries, ~250 members and growing

• Proto-collaboration formed. KEK-IPNS and • International steering group UTokyo-ICRR • International conveners signed a MoU for • International chair for international cooperation board of representative (IBR) on the Hyper- •International Advisory Committee Kamiokande project. (HKAC) 3 Proto-Collaboration

IRFU, CEA Saclay (France) Gifu University (Japan) Laboratoire Leprince-Ringuet, Ecole Polytechnique (France) High Energy Accelerator Research Organization (KEK) (Japan) Lancaster University (UK) Kobe University (Japan) Los Alamos National Laboratory (USA) Kyoto University (Japan) Louisiana State University (USA) Miyagi University of Education (Japan) National Centre for Nuclear Research (Poland) Nagoya University (Japan) Pontificia Universidade Catolica do Rio de Janeiro (Brazil) Okayama University (Japan) Queen Mary, University of London (UK) Osaka City University (Japan) Royal Holloway University of London (UK) Tohoku University (Japan) Seoul National University (Korea) Tokai University (Japan) Seoyeong University (Korea) University of Tokyo, Earthquake Research Institute (Japan) State University of New York at Stony Brook (USA) University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory (Japan) STFC Rutherford Appleton Laboratory (UK) University of Tokyo, Institute for Cosmic Ray Research, Research Center for Sungkyunkwan University (Korea) Cosmic Neutrinos (Japan) The California State University Dominguez Hills (USA) University of Tokyo (Japan) TRIUMF (Canada) University of Tokyo, Institute for the Physics and Mathematics of the Universe University Autonoma Madrid (Spain) (Japan) University of British Columbia (Canada) Tokyo Institute of Technology (Japan) University of California, Davis (USA) Boston University (USA) University of California, Irvine (USA) Chonnam National University (Korea) University of Edinburgh (UK) Dongshin University (Korea) University of Geneva (Switzerland) Duke University (USA) University of Hawaii (USA) Imperial College London (UK) University of Liverpool (UK) Institute for Particle Physics Phenomenology, Durham University (UK) University of Oxford (UK) INFN and Dipartimento Interateneo di Fisica di Bari (Italy) University of Pittsburgh (USA) INFN-LNF (Italy) University of Regina (Canada) University of Warwick (UK) INFN and Università di Napoli (Italy) University of Rochester (USA) University of Washington (USA) INFN and Università di Padova (Italy) Universidade de Sao Paulo (Brazil) University of Winnipeg (Canada) INFN Roma (Italy) University of Sheffield (UK) Virginia Tech (USA) Institute for Nuclear Research (Russia) University of Toronto (Canada) Wroclaw University (Poland) Iowa State University (USA) University of Warsaw (Poland) York University (Canada)

6/July/2016 The Hyper-Kamiokande Experiment 4 Design Report

1 NOT FOR DISTRIBUTION ONLY FOR INTERNAL USE

DesignReport Version2(Dated: F e bruary7,2016 )

Submitted to the Hyper-K Advisory Committee. 6/July/2016 The Hyper-Kamiokande Experiment 5 Kamiokande Evolution . Three generations of large Water Cherenkov in Kamioka. . Tank design for Hyper-Kamiokande optimized .

Kamiokande Super-Kamiokande Hyper-Kamiokande (1983-1996) (1996-) (2026-)

3kton 50kton 0.52Mton=520kton (380kton fiducial) x17 x10 (x20 fiducial mass) arXiv:1109.3262 arXiv:1309.0184 6/July/2016 The Hyper-Kamiokande Experiment PTEP 2015, 053C02 6 Tank Optimization Super-K (SK) Letter-of-Intent 2011 2 Tanks w/ High (LoI) configuration Photocoverage Total Volume 0.05Mton 1Mt 0.52Mt (Fiducial Volume) (0.022Mt) (0.56Mt) (0.38Mt) Dimension 39mf × 42m (H) 48 (W) × 54 (H) × 74mf × 60m(H) ×2 250 (L) m3 ×2 ID #of Photo- 11k (Super-K PMT) 99k (Super-K PMT) 80k (B&L) sensors (40%) (20%) (40%) (coverage) Single-photon 12% 12% 24% detection efficiency Photon-yield 1 0.5 2 Single-photon ~2nsec ~2nsec 1nsec timing resolution

•Optimized tank design based on physics, technology, costs. •2 High Photocoverage tanks 74mf × 60m(H)

•A second identical tank 6y after the first. Being optimized. 7 Cavern/Tank • The candidate site located in Tochibora, under Mt. Nijugo- yama: – ~8km south from Super-K, 295km from J-PARC, 2.5 off-axis – Overburden ~650m (~1755 m.w.e.) HK SK • Details of cavern construction addressed: – Cavern can be built with existing technologies. • Tank lining, PMT support, construction timeline ready.

2nd water 1st water room room

ID OD

Approach and outer incline tunnels6/July/2016 The Hyper-Kamiokande Experiment 8 Photosensor Improvements Photo Multipliers (PMTs) • Efficiency x 2, Timing resolution x 1/2 • Pressure tolerance x 2 (>100m) • Enhance p→ν 퐾+ signal, solar , neutron signature of np→d+g(2.2MeV),.. Hyper-K PMT Super-K PMT 50cm HQE Venetian Blind Box&Line PMT

Box-and-Line Dynode Super-K PMT Other Developments: Hybrid Photo Detectors (HPDs) Multi-PMTs Working concept from 33 8cm(3-inch) PMTs KM3NeT but: OD • Usage for ID/OD • lower pressure tolerance required. 50cm HQE HPD Under viability • ultrapure water. study w/ 20mm6/July/2016 f AD The Hyper-KamiokandeID Experiment1 concept International contribut9 . Photosensor Improvements Photo Multipliers (PMTs) • Efficiency x 2, Timing resolution x 1/2 • Pressure tolerance x 2 (>100m) • Enhance p→ν 퐾+ signal, solar , neutron signature of np→d+g(2.2MeV),.. Hyper-K PMT Super-K PMT 50cm HQE Venetian Blind Box&Line PMT

Box-and-Line Dynode Super-K PMT Other Developments: Hybrid Photo Detectors (HPDs) Multi-PMTs Working concept from 33 8cm(3-inch) PMTs KM3NeT but: OD • Usage for ID/OD Established MoU with KM• 3lowerNeT to pressureexchange knowledge on mPMT technology.tolerance required. 50cm HQE HPD Under viability • ultrapure water. study w/ 20mm6/July/2016 f AD The Hyper-KamiokandeID Experiment1 concept International contribut10 . Tests in water Tests in the EGADs tank EGADS 200t tank 240 in total • The aim of 200t EGADS ~ 7 m (Kamioka) is to test Gd for addition in SK, but agreed to use it to test new PMTs for Hyper-K. • Tests ongoing since 2013.

Validation test of cover at Kamisunagawa in 60 m / 80 m water Prototype of cover to stop chain implosion Using vertical shaft Confirmed with with monitoring artificial implosion 15 mm acrylic at central PMT

Stainless steel (3 mm) • No damage for all tests: – 3 times w/cover (2 with surrounding PMTs) Water – OK for 60m (HK), and for 80m also Down to 60m / 80m • Cover established for HK. 64.8/July/ 2016mΦ (w/ reflector tape forThe monitor) Hyper- Kamiokande Experiment 11 Hamamatsu new plant for mass production

• New large plant for mass production for HK built by Hamamatsu. • The PMT division is moving there. • Around 6 years for mass production. 6/July/2016 The Hyper-Kamiokande Experiment 12 Tokai to Hyper-Kamiokande Use upgraded J-PARC neutrino beam line (same as T2K) with expected beam power > 1.3MW, 2.5° off-axis angle, narrow-band beam at ~600MeV. 6m 10m

TITUS Near ND280 detector to continue for Hyper-K; 50m

Intermediate (at ~1,2 km) WC detector being investigated. Two proposals: 14m

• Off-axis angle spanning orientation. arXiv:1606.08114 [physics.ins-det] • Gd loading, magnetized μ range detector. • Will merge in unique detector/ arXiv:1412.3086 [physics.ins-det]

collaboration. The Hyper-Kamiokande Experiment 13 NuPRISM

J-PARC Neutrino Beam Upgrade Continuous upgrade of neutrino beam up to 2030. • 0.75 MW by MR upgrade starting HK in 2018 • 1.326 MW by 2026 by increasing rep. rate to 0.86 Hz • 3.2e14 protons per spill

“J-PARC upgrade for HK is the highest priority", KEK Project Implementation Plan, N. Saito, at the Third International Meeting for Large Neutrino Infrastructures (KEK, 30 May-1 June 2016).

6/July/2016 The Hyper-Kamiokande Experiment 14 The Hyper-Kamiokande Timeline FY 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2015

Operation Suvey, detailed design Cavity excavation Tank construction

Access tunnels Sensor installation

Photosensor development Photosensor production Water filling Beam up to 1.3MW

• 2018 - 2025 HK construction. • 2026 onwards CPV study, Atmospherics , Solar , Supernova , Proton decay searches, … • The 2nd identical tank starts operation 6yrs after the first one.

6/July/2016 The Hyper-Kamiokande Experiment 15 10 yrs data taking. Expected Events 푒 appearance  beam  beam

Difference from d퐶푃=0

d퐶푃 = 0, 180 can be distinguished using shape information. d=0 Signal Wrong sign 휇 ,  μ Beam 푒,  푒 NC (μ→푒 CC) appearance CC contamination  2300 21 10 362 188 beam  1656 289 6 444 274 beam 16 10 yrs data taking. Expected Events  appearance 푒 μ disappearance  beam  beam No oscillation

2 sin θ23=0.5  beam

Difference from d퐶푃=0

 beam

d퐶푃 = 0, 180 can be distinguished using shape information.

휇 ,  μ 휇 CC Others d=0 Signal Wrong sign 휇 ,  μ Beam 푒,  푒 NC CCQE nonQE (μ→푒 CC) appearance CC contamination  2300 21 10 362 188  8947 4444 721 beam beam  1656 289 6 444 274  12317 6040 859 beam beam Hyper-K Sensitivity to d퐶푃

Exclusion of sind퐶푃=0 sind퐶푃=0 exclusion • >8σ(6σ) for d퐶푃=-90°(-45°) • ~80% coverage of d퐶푃 parameter space with >3σ

From discovery to d퐶푃 measurement: • ~7° precision possible

10 yrs sind퐶푃=0 1s error d퐶푃 1s error exclusion

>3σ >5σ d퐶푃=0° d퐶푃=90° PTEP* 76% 58% 7.5° 19° 2 Tanks 78% 62% 7.2° 21°

* PTEP 2015 (2015) 053C02 updated physics results with LoI tank configuration Effect of configuration change is limited. 18 Precision measurements

2 -5 2 δ(Δm 32)~1.4×10 eV Mass hierarchy sensitivity in combination with reactor. 90%CL 2 2 δ(sin θ23)~0.015 (for sin θ23=0.5) 2 sin2θ23=0.5 ~0.006 (for sin θ23=0.45) Octant determination input to models.

5s

3s

sin2θ23=0.45

6/July/2016 The Hyper-Kamiokande Experiment 19 19 Mass Hierarchy and Octant Sensitivity: Atmospherics NH Variety of physics with NH atmospheric : IH • MH,  octant, CP 23 IH • Sterile neutrino , LV, etc With atmospheric alone, • mass hierarchy sensitivity Mass hierarchy θ23 octant • >3s octant determination for determination determination | 23 -45°|>8°

10 yrs Mass Hierarchy (σ) 10 yrs Octant (σ) NH Atm Atm+Beam NH Atm Atm+Beam

PTEP 23=0.4 3.8 6.9 23=0.45 3.6 7.2

23=0.6 8.4 9.9 23=0.55 2.7 4.0

2Tanks 23=0.4 2.2 5.3 23=0.45 2.2 5.8

23=0.6 5.2 6.9 23=0.55 1.7 3.7

6/July/2016 The Hyper-Kamiokande Experiment 20 Mass Hierarchy and Octant Sensitivity: Atmospherics + Beam 1,5,10 yrs exposure. NH Variety of physics with 10yrs 10yrs 5yrs atmospheric : 5yrs • MH,  octant, CP 23 1yrs 1yrs • Sterile neutrino , LV, etc With atmospheric alone, • mass hierarchy sensitivity • >3s octant determination for Mass hierarchy θ23 octant | 23 -45°|>8° determination determination

10 yrs Mass Hierarchy (σ) 10 yrs Octant (σ) NH Atm Atm+Beam NH Atm Atm+Beam

PTEP 23=0.4 3.8 6.9 23=0.45 3.6 7.2

23=0.6 8.4 9.9 23=0.55 2.7 4.0

2Tanks 23=0.4 2.2 5.3 23=0.45 2.2 5.8

23=0.6 5.2 6.9 23=0.55 1.7 3.7

6/July/2016 The Hyper-Kamiokande Experiment 21 Proton Decay Sensitivity, p → 풆+ ퟎ Proton decay p → 풆+ ퟎ is a favoured model of many GUTs. Similar analysis as in SK but with neutron tagging (remove events with a tagged neutron) thanks to improved PMTs. 3σ discovery potential reaching t ~ 1035 yrs. Similar sensitivity to PTEP, tproton=1.4×1034years (SK 90% CL limit) thanks to the neutron tagging. Free Proton Enhanced signal 0 < Ptot < 100 MeV/c atm. bkgd

BoundProton Enhanced 100 < Ptot < 250 MeV/c

LAr discovery potential computed using 22 numbers from DUNE CDR 2015. Other Proton Decay Sensitivities Proton decays into a lepton and a kaon are one of the most prominent features of Supersymmetric Grand Unified Theories. 3σ discovery potential tproton=6.6×1033years (SK 90% CL limit) 퐾+  + 퐾+  +0 (BR 65%) (BR 21%)

Hyper-K will be sensitive to a wide Bound p p → 풆+ h variety of further proton decay modes, Free p h → gg and is expected to have sensitivity that exceeds current limits by an order of magnitude or more. 6/July/2016 The Hyper-Kamiokande Experiment 23 Solar neutrino physics Day-night From no Day-Night asymmetry asymmetry From KamLAND best fit params observation Sensitivity vs time

6.5 MeV Energy threshold

● Spallation background = 2.7 x SK 2 tanks staged ● Sensitivity to address solar and 1 tank reactor neutrinos discrepancy. ● Sensitivity between solar and reactor Spectrum upturn discovery sensitivity as a function of neutrino parameters by day-night observation time. asymmetry is ~6s 3.5 MeV Energy threshold ● Spectrum upturn observation at ~5s 6/July/2016 level. No observation with LoI talk.24 Supernova Burst Neutrinos 푒 from neutronization:12~80 ev SN directional info SN explosion mechanism by  + e scattering

Galactic SN (<1 Mpc) ● Large statistics: 104,000~158,000 events (10kpc) ● Time spectrum of SN: SN model separation, SN burst time ● Energy spectrum measurement: DE/E~20% at 10-20 MeV ● Direction, time, fluctuations of  flux Nearby Galactic SN (>1 Mpc): ~2-20 SN for 20y 25 SuperNova Relic Neutrinos Supernova Relic Neutrinos: • Diffused or integrated  from past SN • Detectable with enough sensitivity • Measurement will probe: − Star formation rate − Energy spectrum SN  − … HK target window 16-30 MeV

• Use neutron tagging. • Expected events in HK in 10y: ~98 ± 20 (4.8s).

6/July/2016 The Hyper-Kamiokande Experiment 26 Summary of Physics Potential 2Tanks (10 yrs)

Beam d퐶푃 precision (0°,90°) 7°-21° (1.3 MW) CPV coverage (3/5σ) 78%/62% 2 sin θ23 error (for 0.5) ±0.015 Atmospherics+Beam MH determination >5.3σ (sin2θ23=0.40)

Octant (sin2θ23=0.45) 5.8σ Proton Decay p → 푒+ 0 90%CL 1.2×1035 yrs

p → 휈 퐾+ 90%CL 2.8×1034 yrs Solar Day/Night (from 0/from 12σ/6σ KamLAND) Upturn ~5σ Supernova Burst 104k-158k Nearby galaxies 2~20 events Relic 98evt/4.8σ 27 Hyper-K Posters P1.008 Performance evaluation of the 50 cm Box-and-Line PMT for Hyper-Kamiokande Daisuke Fukuda, Okayama University, Japan P1.009 The underwater test of new photo-detectors for Hyper-Kamiokande Fumimasa Muto, Nagoya University, Japan P1.010 Mechanical characteristics of new photodetectors and covers for Hyper-Kamiokande Shoei Nakayama, Kamioka Observatory ICRR University of Tokyo, Japan P1.091 Low energy triggering for Hyper-Kamiokande Thomas Dealtry, Lancaster University, UK P2.021 Sensitivity of new physics by joint analysis of neutrino oscillation on Hyper-Kamiokande Miao Jiang, Kyoto University, Japan P3.006 Development of neutron tagging algorithm for Hyper-Kamiokande with pure water Yuji Okajima, Tokyo Institute of Technology, Japan P3.007 TITUS as a new intermediate detector for T2K and Hyper-Kamiokande Charles Simpson, University of Oxford/Kavli IPMU, UK P3.019 Development and performance evaluation of large-aperture hybrid photo-detector for Hyper-Kamiokande Tianmeng Lou, University of Tokyo, Japan P3.025 The WAGASCI detector as an off-axis near detector of the T2K and HK experiments Benjamin Quilain, Kyoto University, Japan P4.027 A multi-channel optical module for the Hyper-K experiment Gianfranca De Rosa, INFN and University of Naples, Italy P4.028 Hyper-Kamiokande and neutrino astrophysics Takatomi Yano, Kobe University, Japan P4.084 Detecting fast time variations in the supernova neutrino flux with Hyper-Kamiokande Jost Migenda, University of Sheffield, UK 28 Conclusions • New Optimized detector tank configuration: − Higher photodensity, improved PMTs. − Cavern can be built with existing technology − Improved low energy physics performance • Intensive world-wide R&D − PMT production plant built by Hamamatsu • CP violation: − d퐶푃 precision 7%(21%) for d퐶푃 =0(90) − ~80% coverage of d퐶푃 at 3s • Proton decay: − Measure p → 풆+ ퟎ (p→ν 퐾+) at ~1035(1034) − Many other states can be measured • A wealth of physics (atmospherics, SN, solar,…) • Possible intermediate detector being studied. • New members are welcome to help define and build the experiment and….

After two Nobel Prizes for (Super-)Kamiokande don’t miss the occasion to get the third one!

6/July/2016 The Hyper-Kamiokande Experiment 30 Additional slides to peruse

6/July/2016 The Hyper-Kamiokande Experiment 31 PhotoDetector Candidates Photo Multipliers (PMTs) Venetian High QE Dynode Blind Photocathode Improvement

Box- HQE SK PMT 50cm HQE Super-K PMT and-Line Box&Line PMT Used in SK for 20 years Under Viability Test Dynode Under Viability test

Hybrid Photo Detectors (HPDs) Avalance Photo diode Larger Larger Avalance Aperture Diode

20 cm HPD 50cm HQE HPD 50cm HQE HPD Under Viability Test w/ 5mm f AD w/ 20mm f AD Already Developed. Under Development Low Collection Efficiency 6/July/2016 The Hyper-Kamiokande Experiment 32

50 cm HQE Box&Line PMT Multi-Channel Optical Module 1 of concepts • Working concept from KM3NeT but: Based on 33 8cm(3-inch) PMTs From single large PMT to multiple smKMall P3MNETTs: – peripheral Inner Detector/Outermulti-PMT optical module OD Detector. – lower pressure tolerance required. – ultrapure water. ID • Large fiducial volume by directional 20cm PMT for OD sensitivity cut and lessDev elodeadped by the KM 3Nearea.t collaboration for the Mediterranean km3 neutrino telescope. Under investigation by the IceCube-Gen2 collaboration for neutrino telescope in ice. 20” PMTs not very pressure resistant, although lots of R& D (see talk Y.Nishimura). • No geomagnetism compensation.mPMTs are encased in pressure vessel. 3’’ PMT Natural solution for in-water electronics. Dark box setup to • Many PMTs and readoutT. Feusels (UBCchannels.) mPMT R& D 27/ 10/ 2015 2 / 10 measure dark • Acrylic pressure vessel: and position − low radioactive background dependent − high optical transmittance resolution − contain radon from PMT glass − pressure vessel for protection of PMTs and electronics. − same vessel and electronics for Inner and Outer (veto)Detector

6/July/2016 The Hyper-Kamiokande Experiment 33 Electronics and DAQ Systems Candidates for signal digitization: • Charge to Time converter with FPGA- based TDC (similar to SK) QTC evaluation • ~100MHz FADC + digital signal board processing •Digitizers based on capacitor array Required specifications: 0.1 p.e. to 1250 p.e., ΔT=sub-nsec, Ch-by-Ch self triggered digitization, and < 1W/ch By Jin-Yuan Wu Front-end electronics and network connections under water • Need redundant, fail-safe system • DAQ system above water reads out all the digitized hit signals Simple majority trigger and intelligent trigger will follow Use of GPUs, new algorithms to reduce noise. Front-end module schematic diagram 34 Hyper-K Calibration Hyper-Kamiokande detector calibrations has been designed based on Super-K calibrations Feasible techniques/methods in Hyper-K Several R&D projects are in progress to develop more sophisticated calibration systems and sources for Hyper-K

Automated Integrated Compact Photosensor calibration light injection neutron Test Facility system system generator

6/July/2016 The Hyper-Kamiokande Experiment 35 Upgrade of J-PARC Neutrino Beam • All components will be able to receive the 1.3 MW beam when it is ready • Current limitations and achievable limitations for the neutrino beam line:

6/July/2016 The Hyper-Kamiokande Experiment 36 Past Hyper-K Configuration

6/July/2016 The Hyper-Kamiokande Experiment 37 Past• Water Hyper Cherenkov-K, proven Configuration technology & scalability: • Excellent PID at sub-GeV region >99% • Large mass → statistics always critical for any measurements. Total Volume 0.99 Megaton Inner Volume 0.74 Mton Fiducial Volume 0.56 Mton (0.056 Mton ´ 10 compartments) Outer Volume 0.2 Megaton Photo-sensors • 99,000 20”Φ PMTs for Inner Detector (ID)(20% photo-coverage) • 25,000 8”Φ PMTs for Outer Detector (OD) Tanks • 2 tanks, with egg-shape cross section » 48m (w) ´ 50m (t) ´ 250 m (l) • 5 optically separated compartments per tank 6/July/2016 The Hyper-Kamiokande Experiment 38 6/July/2016 The Hyper-Kamiokande Experiment 39 p → 푒+ 0 p→휈 퐾+ 3s discovery potential 3s discovery potential

90% CL sensitivity 90% CL sensitivity

6/July/2016 The Hyper-Kamiokande Experiment 40