Hyper-Kamiokande project
Masato Shiozawa (Kamioka Observatory, ICRR)Does proton decay?
Direct evidence for particles unification• Standard model is just an

approximation of unified theory（many of us believe）• In grand unified theory,• Three forces are unified• Q :Q :Q = 3:2:1• Accommodate tiny ν mass
• Prediction of proton decays• Proton decay experiments• Direct probe to GUT• Explore new paradigm of particlese-u

Unification offorcesdProtonPositron0
Direct transition
between positron(lepton) and dquark2

Neutrino
Messenger from nature• Neutrino does mix• Particle-antiparticle asymmetry?
(CP violation?)• Key to understand universeʼs matter dominance•• Neutrino mass ordering?
• Feasibility of 0νββ discovery experiments• What is the origin of tiny ν mass & large mixing?
• Whatʼs roles of neutrinos in nature?
• Driver of Supernova explosion?
• Probe to the interior of Sun, Earth, Universe
Tiny (<10-6 of electron) neutrino masses

3

Present

2026-

Super-K, 22kton Fid. mass

J-PARC 470kW beam (T2K)

SK-Gd(201X~)

J-PARC >750kW (T2K-II)

Hyper-Kamiokande
2026~, 190kton mass, >1.3MW beam

• Japan-based seamless program to gettimely results• Rich physics, big chance of discoveries
4Hyper-Kamiokande
MW-class J-PARC beam

Supernova
Atmosphere

ν

ν

ν

ν

~10 x Super-K fiducial mass
~2 x Super-K photon sensitivity
Hyper-Kamiokande•Tank 60m(H) x 74m(D)•Total mass 260 kton
Fducial 190 kton•~50,000 PMTs

Ultra-sensitive
PMTs (2 x Super-K)

Sun

3

ンでのカウントをグラフ化（標準球のカウントを同じにした場合）

ns FWHM without ringing, which is faster tha

2Hyper-K PMT
	~2

Super-K PMT. The time resolution for single P

5time peak in Figure 59 and 7.3 ns at FWHM,

6would be an important factor to improve the re

7

The nominal gain is 107 and can be adjuste

82200 V. Figure 60 shows the charge distribution

9

better compared to the 50% of the Super-K PM

10

the ratio of the height of the single PE peak toー Hyper-K
ー Super-K

Entries (a.u.)Single Photon Detection
Relativesingle photoelectron
hit efficiency
Efficiency(arbitrary)

50cmΦ Hyper-K PMT
4

1

Super-K PMT
	

50cm high-QE box&line PMT
50cm Super-K PMT

0 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
Position angle [degree]

Injection position (degree)
入射光子数が一定になる様補正してあるが、QEとCEの固体差が含まれている。

-20 -15 -10、同一光子数を入射したと仮定した場合のカウント値に歴然と差があることが分かる。

-5

0

5

10

15

Time [nsec]

20 25Time [nsec]• Efficiency x 2, Timing resolution x 1/217• Pressure tolerance x 2 (>100m)• Enhance detector performance

FIG. 59. Transit time distribution at single photoelectron, compared with the Super-K PMT in
dotted line.

by better detection of faint signal, e.g. solar ν, SN ν,
proton decay & background signature 2.1.4. Gain Stability
11

6

Hyper-Kamiokande tank design
HK Design Report : KEK Preprint 2016-21, ICRR-Report-701-2016-1- Fid. mass 190 kton, an order of mag. larger than Super-K- Light yield: ~2 x Super-K(Single tank parameters)
H60m×D74m• Total Mass 260 kiloton
Fiducial Mass 190 kiloton• Photo-sensors (innerdetector) : 40,000 pieces
giving 40% photo-cathodecoverage

D:74m

H:60m

• Cylindrical tank :New PMT• New PMT enables the water tanks to be smaller, thereby
reducing construction costs, without sacrificing its physics• 2-tanks in stage: priority to realize the 1st tank ASAP

7

Hyper-K proto-collaboration
Inaugural Symposium@Kashiwanoha,
January 2015

Hyper-K meeting@London, July 2016

• Hyper-K proto-collaboration has been established andis growing• 15 countries, 73 institutes, ~300 members, ~75% from abroad• MoU between 2 host institutes: UTokyo/ICRR and KEK/IPNS• Int. Hyper-K Advisory Committee to develop the program
8

Notional Timeline (1st Tank)
FY 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026
2015
Survey, Detailed design
Access tunnels
Photo-sensor
development

Operation

Cavity excavation
Tank constructionwaterfilling

Photo-sensor production

sensor installation

DUNE non-beam• 2018〜2025 HK construction
CPV study• 2026〜

DUNE beam

Atm・Solar・Supernova ν study, Proton decay searches

9Toward approval• Science Council of Japan has
selected Hyper-K as one ofImportant Large Scale Projectin Materplan2017•MEXT (Japanese funding agency) will revise
the list of important large-scale projects(Roadmap) in this summer•UTokyo/ICRR are preparing for the MEXT

review and construction budget request
10

Contents• Overview of Hyper-Kamiokande Done!
• Proton decay search• Accelerator ν study• Atmospheric ν study• ν astrophysics and astronomy

11

Proton Decays- present and future -12Motivation of Nucleon Decay Searches• Only way to directly prove GUT• Two major modes predicted by many models
Mediated by gauge bosons

p

u
u
d

g

g

X

SUSY mediated

!
e!
+

d π0
d

p→e+π0

p

u ∼"
φ3"
d
u

ν"!

∼"
µ"
∼"
∼"
W
c

su

p→νK+

!

5

tan " #m p
g4 m 5p!(p " ! K + ) ~"( p # e+$ 0 ) ~2 #M 2M4M
3Xq!
0 )= 3.7&1029±0.7 years
p # e+$to
We%(needpursue both decay modes for discovery,
2

•

K+#

given the variety of predictions※Searches for other modes are also important13

Other modes are also important• First discovery might happen in exotic decay modes.
- Many models predicts branching ratio of p→e+η, e+ρ, e+ωdetails of unification picture,e.g. gauge group and othersymmetries- Γ(n→νπ0)/Γ(p→e+π0)
depends on SU(5), SO(10),E6 (Y. Muramatsu)

𝟏𝟏𝑒 model
points
𝟏𝟏𝟒 model
points𝟐• We expect to identify

0)/Γ(p→e+π0)Γ(p→μ𝑹+K=

are 10~20%- Flipped SU(5) (Ellis) predicts Br(p→e+π0)~Br(p→μ+π0)

𝑹𝟏 =By Y. Muramatsu0Γ(n→νπ )/Γ(p→e+π0)14Water Ch. detector for p-decays

Super Kamiokande IV 1775.6 days : Monitoring300

μ-likee-like 3985
e-likemuon-like 3915

CCQE electron

CCQE muon

250
200
150
100
50

• High mass is possible (1Mton ~ 20×Super-K)• p→e+π0, νK+, and more can be searched

0
-10

-8

• Free protons are available• No nuclear effect, Fermi motion• High efficiency & good S/N separation

-4

-2

0

2

4

6

8

10

PID likelihood sub-GeV 1ring (FC)PID likelihood (atmν)with unprecedented sensitivities• Excellent & well-proven performance• Good ring-imaging capability at ~1GeV• Excellent particle ID (e or μ) capability > 99%• Energy resolution for e and μ ~3%-6p→e+π0!in!16O!
!e+!

!π+!
!π0!

Free!proton→e+π0!
!e+!

!π0!

15

Experimental limits and models∅∅∅‣Super-K provides world stringent limits‣Many models predict τ=O(1034-35) years‣Discovery could be around corner!

16

p→e++π0
searchese+!

Super-K cut!
 2 or 3 Cherenkov rings"
 All rings are showering" 85 < Mπ0 < 185MeV/c2 (3-ring)"
 No decay electron"
 800 < Mproton < 1050 MeV/c2"
Ptotal < 250 MeV/c "γ#γ#

SK-II (half PMT) forward-backward display for p!e++π017Recent improvement (1)Beacom and Vagins PRL93:171101(2004) !

Neutron tagging to reduce background events•BG: often accompanied with neutrons by neutrino primary interactions
and secondary int. in water‣proton decay: neutron emission from residual nucleus is small.

Since SK-IV we have started recording faint signature of neutrons;
n+p→d+γ(2.2MeV, τ~200μsec), BG reduction by ~2
SK-IV 1297days atmν Data
Number of events (/Mt*yr)

p→e+π0 BG Monte Carlo
1.6

Atm.ν MC after all cuts for e+π0Black: Tagged by 2.2 MeV γ
Red: Captured by H

Black: Tagged γ
average~0.9

1.4
1.2
1
0.8

Red: True neutrons
average~4

0.6
0.4
0.2
0

Tagged γ’s Timing (μsec)

0

2

4

6

8

10

12

14

16

Number of
Number of neutrons
orneutron
γ’s 18Recent improvement (2)Shiozawa, talk@NNN00-Fermilab

Tight momentum cut to make BG-free box• Ptot < 250 MeV/c (SK cut)
BG=2.2 ev/Mtonyrs, eff.=44%

free proton ! e+π0

BG reduction by ~15• Ptot < 100 MeV/c (tighter cut)
BG=0.15ev/Mtonyrs, eff.=17.4%

20 Mtonyrs atmν BG MC

main target is free proton decays
bound proton decay
16O ! 15N e+π019Proton decays into lepton+meson
PRD 95, 012004 (2017)
signal MC(free proton)
BG MC
Data

Signal box w/ Ptot < 100MeV/c
Signal box w/
100 < Ptot < 250 MeV/c

20

Proton decays into lepton+meson
PRD 95, 012004 (2017)

paper under preparation•p→e+π0•0 candidates (40% eff. & 0.61BG)•τp/Br > 1.6 x 1034 yrs•p→µ+π0•2 candidates (40% eff. & 0.87BG),
one is rejected after energy recalibration•τp/Br > 7.7 x 1033 yrs

21

+p→ν+K searches100

PRD90, 072005 (2014)

K+ is below Cherenkov threshold→ 236MeV/c μ and muon decay
electronsγ"µ+! e+
16O!

+!
ν" K

80

60

40

20

Tag de-excitation γ from 15N* to reduce BGν"

Number of Events(I) K+→μ+ν, μ+→e+ννSuper-Kamiokande I-IV

16O→νK+15Nγ, K+→µ+ν"

0

µ+!

γ"

Many efforts to improve analyses

200

225

250

275

300

Pµ(MeV/c)

e+"
t!

10

2

Super-Kamiokande
I, III, IV
SK-I/III/IV
Dot: Data
Box: ATM MC
Hist: PDK MC(arbitrary norm.)

10

11.γ tagging efficiency algorithm has been improved. 10
2.high muon decay electrons efficiency in SK-IV
electronics.
10
3.better momentum reconstruction is employed.
0
-1

-2

20

40

Number of γ hits

60

80

22

+
p→ν+K searches

PRD90, 072005 (2014)(II) K+→π+π0γ"

γ"backward π+"‣π0 efficiency was improved by dedicated
π0 finding algorithm‣Shape information of π+ hits for BG
reduction

p→ν+K+- 260 kton×years exposure (SK-I+II+III+IV)- τproton/Br > 5.9 ×1033 years @ 90%CL

Summary of prompt γ and ππ searches
PRD72,052007
SK-I paper in 2005

91.7 kt y

14.6%

1.3 evts.

23

Summary of Super-K• p→e++π0 reached to 1034 yrs• (p,n)→(e+,μ+)+(π,η,ρ,ω) 1032~1034 yrs• SUSY favored p→νK+ > 5.9×1033 yrs• No excess in K0S, K0L, νπ0, νπ+• test many decay modes• di-nucleon decays (|ΔB|=2)• pp→K+K+ > 1.7×1032 years• pp→e+e+ > 1033 years• np→ (e+,μ+,τ+)+ν
• neutron-antineutron oscillations• p→ (e+,μ+)+νν, (e+,μ+)+X• radiative decays p→(e+,μ+)+γ
Still single event discovery is possible.
Discovery could be around corner.

24

+
0
p→e π search in Hyper-K• Hyper-K is only realistic approach to proton lifetime

ts

Number of Events

beyond 1035 years
10
9
8
7
6
5
4
3
2
1
0
10
9

Hyper-K 10 years~9σ discovery
0"<"ptot"<"100"MeV/c"

p→e+π0 signal(τp=1.7 x 1034 years)

Atmospheric ν
background

600

800

1000

Invariant Proton Mass (MeV/c2)

1200
25

+
Proton decay (p→νK ) search‣Discovery reach (3σ)‣τ(p→νK+)~1×1034years（HK 10yrs）‣Limit (90%CL)‣τ(p→νK+)>3×1034years（HK 10yrs）

Number of events

p→νK+τproton=4×1033年

12

5.6 Mton year exposure
33（SKlifetime
90% CL
limit）
year
Proton4.0x1016

mono
fro chrm om
K + atde ic μ
cay +

10

8

6

4

τproton=4×1033年（SK 90% CL limit）

K+(& lifet
mo ime
no
ch
ro
ma
tic

14
12
10
8
6
4

2

μ+
)

2

0

BG
200

210

220

230

240

250

260

270

280

Pµ (MeV/c)
μ+ momentum(MeV/c)

0

BG
0

10

20

30

40

50

60

70

80

90

100

K lifetime+
K decay time (nsec)+

Experimental test on Supersymmetry26

Hyper-K’s sensitivities
Improvements in many modes by a factor ~10
Good chance for discovery!
Soudan Frejus Kamiokande IMB
p → e+ π0n → e+ π-

Super-K
1

2 3

4‣p→e++π0‣τproton/Br > 1×1035 years @90%CL‣5Mton×years (9 Hyper-K years)p → μ+ π0
n → μ+ πp → ν π+n → ν π0p → e+ η‣p,n→(e+,μ+)+(π,ρ,ω,η)‣O(1034~35)years

p → μ+ η
n → νη
p → e+ ρ0n → e+ ρp → μ+ ρ0n → μ+ ρ-‣SUSY favored p→ν+K+‣3×1034 years

p → ν ρ+n → ν ρ0p → e+ ω‣K0 modes, νπ0, νπ+ possible

p → μ+ ω
n → νω
p → e+ K 0
n → e+ K n → e- K +p → μ+ K 0
n → μ+ K p → νK+n → νK0
p → e+ K*(892)0
p → ν K*(892)+
n → ν K*(892)0

32

10

10

33

τ/B (years)

34

10

35

10

‣Others‣(B-L) violated modes‣radiative decays p→e+γ, μ+γ‣neutron-antineutron oscillations (|ΔB|=2)‣di-nucleon decays (|ΔB|=2)‣pp→XX..., nn→XX...
27

Neutrino OscillationsT(ν e , ν µ , ν τ )T = UαMNS
(
ν
,
ν
,
ν
)
i
1
2
3

! ! $ ! cos#12
# e & #
# ! µ & = # 'sin # 12#&
# ! " & ##0"% "sin # 12cos# 120

UMNS: Maki-Nakagawa-Sakata matrix!
0 $# cos# 13
&
0 &#
0
&#
i$
1 &%# 'sin # 13e"$
0 sin # 13e'i$ &! 10#&# 0 cos# 23
10&0
cos# 13 &## 0 'sin # 23%"$! ! $
0&# 1 &
sin # 23 &# ! 2 &&&#cos# 23 &%#" ! 3 &%(mi2 − m 2j )LP(ν α → ν β ) = δαβ − 4∑ Re(U U βiUα jU )sin
4Eν
i> j
(

)

(

)

*
αi

*
βj

2

(mi2 − m 2j )L( ± )2∑ Im(U U β iUα jU )sin
2Eν
i> j
*
αi

*
βj

Matter-effect is omitted
here

Neutrino Oscillation Parameters: 6 = 4 matrix elements and 2 mass-squared differences
θ23~45±5oΔm223=2.4×10-3eV2

θ12~34±3oΔm221=7.6×10-5eV2

θ13~9oδ=unknown

Atmospheric,Accelerator
Neutrinos

Solar, Reactor
Neutrinos

Accelerator, Reactor
Neutrinos

Accelerator,
Atmospheric Neutrinos

Mass Hierarchy (Δm232=m23-m22>0 or Δm232<0) is unknown
Octant of θ23 or θ23=π/2 is also interesting question28

CP violation
Only known CPV source=KM phase
Other CPV necessary for the matter-dominated universe→ Search for CPV in lepton sector•Leptogenesis scenario only with ν’s Dirac CP phase

S. Pascoli et al., PRD 75, 083511 (2007) PDG review 2014|sinδ| >~0.6
e.g. Petcov 1504.02402v1 (right plot)

We need not only CPV
discovery, but also precision
measurement

Likelihood
Likelihood @NOD

•Flavor symmetry prediction on δCP

1.0

0.8

BM
GRB
TBM
GRA
HG

0.6

0.4

0.2

0.0
-1.0

-1.0

-0.5

-0.5

0.0

0.5

cos d
0.0
0.5
cosδ

1.0

1.0
29

Hint of leptonic CP Violation
T2K : J-PARC ν beam + Super-K
excluded (90%CL)

T2K2016 w/ reactor
sin2θ13=0.085±0.005
δCP=[-3.13,-0.39]

T2K may start indicating maximal CP violation of |sinδCP| ~ 1 (δCP ~ −π/2)• Urgent topic (world consensus)• Technology established, need more intense beamand larger detector!

30

T2K : NBB + water Cherenkov
T2K (Tokai to Kamioka) experimentHigh intensity  beam from J-PARC MR to Super-Kamiokande @295km

Discovery of e appearance  Determine 13
Last unknown mixing angle
 Open possibility to explore CPV in lepton sector

CP odd term in     e prob.
sin  s12 s23 s13 sin12~0.5, sin23~0.7,“Clean νμ→νe appearance measurement” hasbeen established! →make CPV test possible

Precise meas. of  disappearance  23, m232


sin<0.2)

Really maximum mixing? Any symmetry? Anytihng unexpected?

3• S/N~10 or so, clean νe appearance signal can be observed.
• Key elements are(i) narrow-band sub-GeV clean νμ beam,(ii) 300km baseline, and(iii) high performance large water Cherenkov detector

31

Water Cherenkov technique• For νe appearance in T2K (J-PARC beam)• νe signal efficiency ~60%
• BG recνμ+antiνμCC<0.1%, NCπ0~1%(0.1<E
future)ν<1.25GeV, can be optimized in• Excellent particle ID capability > 99%• Energy resolution for e and μ ~3%• Energy threshold ~5MeV• Supernova ν, solar ν...
• Stable operation• energy scale stability ~1%• livetime for physics analyses > 90%

10-02-17:16:23:39
Inner: 3136 hits, 6453 pe
Outer: 3 hits, 2 pe
Trigger: 0x03
D_wall: 1218.7 cm
e-like, p = 701.5 MeV/c

Charge(pe)>26.7
23.3-26.7
20.2-23.3
17.3-20.2
14.7-17.3
12.2-14.7
10.0-12.2
8.0-10.0
6.2- 8.0
4.7- 6.2
3.3- 4.7
2.2- 3.3
1.3- 2.2
0.7- 1.3
0.2- 0.7
< 0.2

e
1300
0 mu-edecays

1040
780
520
260
0
0

500

1000

1500

2000

Times (ns)Super-Kamiokande IV
Run 999999 Sub 0 Event 458γ

10-02-15:01:36:54
Inner: 3366 hits, 8116 pe

0

νμ π

Outer: 7 hits, 5 pe

Trigger: 0x03

D_wall: 1443.6 cm

e-like, p = 898.6 MeV/c

Charge(pe)Excellent detector performance&
Scalablity

ν
sim e CCula
tionSuper-Kamiokande IV
Run 999999 Sub 0 Event 209

small opening
angle

γ

>26.7
23.3-26.7
20.2-23.3
17.3-20.2
14.7-17.3
12.2-14.7
10.0-12.2
8.0-10.0
6.2- 8.0
4.7- 6.2
3.3- 4.7
2.2- 3.3
1.3- 2.2
0.7- 1.3
0.2- 0.7
< 0.2

π0→γγ

NC
sim 1π 0
ula
tio
n

1400
0 mu-edecays

1120
840
560
280
0
0

500

1000

1500

2000

Times (ns)32Long baseline exp. w/ J-PARC
T2HK: Future LBL plan using J-PARC
Neutrino

ν
μ

ν
μ

295km

e ?
iδ

295km

νe
Same?

νe

Anti-neutrino

KAMIOKA

Neutrino Facility
at J-PARC
295km
TOKAI

Diameter 74m

Sensitivity study
New Hyper-K tank design with
provision of 1.3MW J-PARCν
beam
Systematic uncertainties basedon T2K are taken into account•

Height 78m•

Plug Manhole

Hyper-Kamiokande

ND280
Near Detectors(KEK-JAEA, Tokai)

LoI: The Hyper-Kamiokande Experiment [arXiv:1109.3262v1]•Operation of the magnetized ND280 off-axis detector should
continue for HK with potential upgrades•Two possibilities of a generic intermediate WC detector withthe following potential features:
Off-axis angle spanning orientation,
Gd loading, Magnetized µ range detector•Ongoing study on locating 2nd detector in Korea
33

Upgrade of J-PARC Neutrino Beam•Continuous upgrade plan of the neutrino beam intensity•

0.48 MW stable operation at present•

0.75 MW by MR upgrade starting in ~2019•

1.326 MW by 2026 by increasing rep. rate to 0.86 Hz

KEK Project Implementation Plan (KEK-PIP) put firstpriority to “J-PARC upgrade for Hyper-Kamiokande”

34

Expected events
10 years (13MW×107s)

νμ disappearance

Antineutrino mode: appearance
νe appearance400

ν beam

δ=0
δ = 90δ = -90
δ = 180

300
200
100
0
0

0.2

0.4

0.6

0.8

1

1.2

Reconstructed Energy Erec
(GeV)
ν

400
350

ν beam

δ=0
δ = 90δ = -90
δ = 180

300
250
200
150
100
50
0
0

0.2

0.4

0.6

0.8

1

1.2

Erec
ν (GeV)δ = 90 / δ = 0100

δ = -90/ δ = 0
δ = 180/ δ = 0

50
0
-50
-100
-150
0

0.2

0.4

0.6

0.8

1

1.2

Reconstructed Energy Erec
(GeV)
ν

150
δ = 90 / δ = 0100

δ = -90/ δ = 0
δ = 180/ δ = 0

50
0

-50
-100
-150
0

0.2

SignalWrong sign νμ/νμ
for δ=0(νμ→νe CC) appearance CCν beamν beam

2,300
1,656

21
289

10
6

0.4

0.6

0.8

1

Disappearance ν mode8000ν beamNo oscillation
No oscillation
sin2θ23=0.5

6000

sin2θ23=0.5

4000

2000

00

0.2

0.4

0.6

0.8

362
444

188
274

1.4

1.6

1.8

2

Disappearance ν mode8000ν beamNo oscillation
sin2θ23=0.5

6000

4000

2000

00

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

rec

Reconstructed Energy Eν

Reconstructed Energy Erec
(GeV)
ν

NC

1.2

rec

1.2

beam νe/νe
contamination

1

Reconstructed Energy Eν
Number of events/50 MeV

Difference of events/50 MeV

Difference of events/50 MeV

Difference from δCP=0
150

Number of events/50 MeV

500

Number of events/50 MeV

Number of events/50 MeV

Neutrino mode: appearance

νμ+νμ
CCQE

νμCC OthersnonQE

ν beam 8,947

4444

721

ν beam 12317

6040

859
35

CPV sensitivity

J-PARC ν beam + Hyper-Kσ• Exclusion of sinδ =0• 8σ for δ=-90°• 80% coverage of δ

Normal mass hierarchysinδ
CP=0 exclusion

CP10

sin2θ23=0.50

864

parameter space for CPV
discovery w/ >3σ• δ precision measurement• 20° for δ=-90°• 7° for δ=0°

12

2
0

-150

-100

CP

-50

0

50

100

68% error of δ (degree)δCP 1σ error
60

150

δCP

1.3MW beam
50 1year = 107s

1tank
Baseline(staging)
3tank

40

δCP=90°δCP=0°

30
20
10
0

0

2

4

6

8

Running time (year)

1036Precision measurements
NEW x 9 years (11.25MW×107s)

δ(Δm2∆ m232 [eV2]• Atmospheric parameters-5232)~1.4×10 eV-3

T2K 2014
Hyper-K
Hyper-K + reactor

2.8

90%CL
2.6

→ Mass hierarchy sensitivity
in combination with reactor

2.4∆ m232δ(sin2θ23)~0.015 (for sin2θ23=0.5)~0.006 (for sin2θ23=0.45)• Near detector measurements• Cross sections• Exotic physics searches

3.0 ×102.2
0.4

2.6 ×10

0.45

0.5

0.55

0.6

-3

2.55

0.65

sin θ232Hyper-K+reactor

2.5
2.45
2.4
2.35
2.3
2.25
2.2
0.35

0.4

0.45

0.5

0.55

0.6

0.65
sin2θ2337

2nd Hyper-K detector in Korea?
About 10 years ago, this possibility was discussed.
Phys.Rev.D72:033003,2005
Now this possibility is revisited...
Phys.Lett.B637:266-273,2006
Pyys. Rev. D81, 093001, 201038

Atmospheric neutrinos
primary cosmic rays
primary cosmic rays
atmosphere

pion

ino

electronneutr(0.1 GeV ~ 104 GeV andbeyond)• Wide range of ν baseline(10km downward ~13,000km upward)• νµ:νe ~ 2:1 at productiononeutrin• Wide range of ν energy

ne
utr
ino

pion

uon

39

3-flavor oscillation study
Through the matter effect in the Earth, we study on• Mass hierarchy : resonance in multi-GeV νe or νe: interference btw two Δm2 driven oscill.
• CP δ
: magnitude of the resonance• θ23 octant
III

PHYSICS POTENTIAL“Fractional change of upward νe flux (cosΘzenith=-0.8)”

Ψ(νe)/Ψ0(νe)−1

54

1
0.8
0.6
0.4
0.2
0
-0.2
-0.4

Ψ(νe)/Ψ0(νe)−1

10
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
10

cosΘν=-0.8

NH, sin2θ23=0.4, sin2θ13=0.025, δ=40o

(a)

1
0.8
0.6
0.4
0.2
0
-0.2
-0.4

solar terminterference term
θ13 resonance term
total

ν
-1
cosΘν=-0.8

1

10

10
o
CP=40 or 220o

NH, sin2θ23=0.6, sin2θ13=0.025, δ=220o

1
0.8
0.6
0.4
0.2
0
-0.2
-0.4

(c)

-1

1

Eν(GeV)1010cosΘν=-0.8

NH, sin2θ23=0.6, sin2θ13=0.025, δ=40o(b)sin2θ23=0.4 or 0.6-1

1
cosΘν=-0.8

Hierarchy is
10 NH or IH

IH, sin2θ23=0.6, sin2θ13=0.025, δ=40o

(d)

-1

1

Eν(GeV)

Resonance in νe(not shown) in thecase of IH.
1040νe-like and anti-νe-like sample
sin22θ13=0.1
1.2
Normal‣ Multi-GeV Multi-ring νe‣ Multi-GeV Multi-ring νe-bar

s223=0.6, inverted hierarchys223=0.4, normal hierarchy

1.1s223=0.6, normal hierarchy(b) Multi-GeV  -like
Multi-GeV
νe-likeee

1.05

Inverted

1

0.95
0.9
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
cos 
1.2
s =0.4, inverted hierarchy223s223=0.5, inverted hierarchy

1.15

s223=0.6, inverted hierarchys223=0.4, normal hierarchys223=0.5, normal hierarchy

1.1s223=0.6, normal hierarchy(c) Multi-GeV anti-like−
Multi-GeV
νe-likee0e‣ Multi-GeV (1-ring) νe‣ Multi-GeV (1-ring) νe-bar

s223=0.5, inverted hierarchys223=0.5, normal hierarchy

Oscillated e-like events
Non-oscillated N /N
N /N

Define likelihood to make enhanced samples

s223=0.4, inverted hierarchy

1.15

0
e

νe+N→e−+X
Upward νe−+appearance
νe+N→e +X‣ νe CC produce more positive π+ than νe-bar‣because of negative lepton (e-)‣more muon decays‣ More energy transfer to hadronic system‣more pions and muon decays‣lower charged lepton energy

1R νe-like
1R νe-likeMR νe-likeMR νe-likeanti-νe CC
9%
37%
10%
27%

others
29%
8%
34%
20%

Total
100%
100%
100%
100%

1.05

e

νe CC
62%
55%
56%
53%

1

0.95
0.9
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
41
cos 

Matter effect fit in Super-Kαaα: scale factor
a=sqrt(2) Gf Ne

Normal Hierarchy
Inverted Hierarchy

Δχ2

99%
95%
90%
68%

α

•Best fit α=1 for NH, consistent w/ standard matter effect•Δχ2=5.2 for α=0, Data disfavors zero matter-effect by >2σ42electron’s Up/Down ratioUp(cosΘ<-0.4) to Down(cosΘ>0.4) event ratio for multi-GeV electrons
Multi-GeV
Multi-GeV e-like ν νe-like

Multi-GeV
Multi-GeV e-like ννe-like

e

0.4
0.4

NormalInverted( Up - Down ) / ( Up + Down )( Up - Down ) / ( Up + Down )

0.4
0.4

0.2
0.2

0

-0.2
-0.2

2
-0.4
-0.4

3

2×103

NormalInverted

Normal Hierarchy
Inverted Hierarchy

0.2
0.2

0

-0.2
-0.2

10 GeV
3.5

e

2
-0.4
-0.4
3

44
10
2×104
Lepton P [ MeV ]2×103

10 GeV
3.5

44
10
2×104
Lepton P [ MeV ]Multi-Ring e-like Mulri-ringνMulti-GeV
νe-like Multi-GeV
νe-likeνMulti-Ring e-like Mulri-ring
0.4
e

0.4
0.4

NormalInverted( Up - Down ) / ( Up + Down )( Up - Down ) / ( Up + Down )

0.4

0.2
0.2

0

-0.2
-0.2

-0.4
-0.4
3

3.2 2×103 3.43×103 3.6

2

3

3.8

44
10
Lepton P [ MeV ]e

NormalInverted•Some data points

favors matter-effect•Indication ofexcess at ~5GeV
where resonance is
expected to occur

0.2
0.2

0

-0.2
-0.2

-0.4
-0.4
3

10 GeV

3.2 2×103 3.43×103 3.6

2

3

3.8

44
10
Lepton P [ MeV ]10 GeV43

Atmν data fit w/ fixed θ13
Normal Hierarchy
Inverted Hierarchy•Mass hierarchy: Δχ2 = χ2NH - χ2IH = -4.3 (-3.1 expected)•Under IH hypothesis, the probability to obtain -4.3 or less is 3.1%
(sin2θ23=0.6) and 0.7%(sin2θ23=0.4).
•Under NH hypothesis, it is as large as 45% (sin2θ23=0.6)

44

Atmν data fit w/ T2K

Publicly available T2K data is used as an external constraints
T2K’s constraints on θ23 and Δm232 help sensitivity to mass hierarchy

20

20

Normal Hierarchy
Inverted Hierarchy

10

10

99%

15

∆ χ2

15

∆ χ2

∆ χ2

15

20

10

99%

5

99%

5

95%

5

95%

95%

90%

90%

90%

68%

68%

68%

0
0.001

0.002

0.003

| ∆ m232 | , | ∆ m213 |

0.004

eV

2

0
0.005 0.2

0.4

0.6
2

sin θ23

0.8

0
0

2

4

6

δcp

•SK+T2K: Δχ2 = χ2NH - χ2IH = -5.2 (-3.8 exp’d for SK best point, -3.1 for
combined best)•Under IH hypothesis, the probability to obtain -5.2 or less is 2.4%
(sin2θ23=0.6) and 0.1%(sin2θ23=0.4).
•Under NH hypothesis, it is 43% (sin2θ23=0.6) Paper in preparation

45

Hyper-K sensitivity
νeAtmosphericν + J-PARC beam
Determination possible by 2~3 years(sin2θ23=0.5)νµBand for CP values

Resonance
oscillation (MSW) for• νµ→νe
if Normal Hierarchy• νµ→νeif Inverted Hierarchy46

Search for ν’s inducedby dark matters• provide complemental information w/

direct detection experiments• Sensitive to low mass (GeV/c2) WIMPs

10
10

3
2

10

IceCube, b b
BAKSAN, τ + τ SIMPLE2PICASSO+

W W
bb

WIMP-nucleon SI Cross section[pb]WIMP-proton SD Cross section[pb]Expected sensitivity for Solar WIMPs
WIMP-proton cross section[pb] WIMP-nucleon cross section[pb]
+

W W

-

DAMA
Super-Kamiokande

1
10
10
10
10
10
10

-1

-2
-3
-4
-5

HK 10yrs sensitivity, τ + τ -6

bb

W+ W-

10
10
10
10
10
10

10

10

WIMP mass[GeV/c]

DAMA
CoGENT
CRESTIICDMSII si
XENON100
LUX
SuperCDMS
Super-Kamiokande

-3

-4

-5

-6

-7

HK 10yrs sensitivity, τ + τ -bands showing astrophysical uncertainties

2

-2

10

-8

bb

W+ W-

bands showing astrophysical uncertainties

10

10

2

47
WIMP mass[GeV/c]47

ν astophysics, ν telescope48

Why Supernova neutrinos?
Only neutrinos, with their extremely small interaction cross sections, canenable us to see into the interior of a star...
John N. Bahcall, Phys. Rev. Lett. 12, 303 (1964)
Neutrinos hold the keys to solve many outstanding questions:• What is the supernova explosion mechanism?
• What is the physics at high temperature and density?
• Do black holes form? How and when?
• What is the interior environment like?
• Was there a jet? An accretion disk?
• What nucleosynthesis products are made?
• What is the nature of physics at very high neutrino density?
• What are the properties of neutrinos?
• Which explosions are indeed core collapse?
• …etc…

Slide adopted from Horiuchi@HK meeting49

Distance scale and exp’d rate
Distance*Scales*and*Detec0on*Strategies*
Milky way

Nearby galaxies distant galaxies

N%>>%1%:%Burst%N%∼%1%:%MiniFBurst%

kpc%

Mpc%

N%<<%1%:%DSNB%
Gpc%

Rate%∼%0.01/yr% Rate%∼%1/yr%

Rate%∼%108/yr%

high%sta?s?cs,%
all%ﬂavors%

cosmic%rate,%average%emission%

object%iden?ty,%
burst%variety%Beacom@NU2012

50

Supernova Burst Neutrinos

νe from neutronization:
100,000~160,000 ev
12~80 ev
(2Tanks 440kt, 10kpc (GC))

NC: 3,000~5,000 ev
ν	

γ#

ν	
γ"

~1o pointing
accuracy

Case a)!
T=8MeV(νx)!
T=5MeV(νe)!
µ=0!

γ"Case b)!
T=6.26MeV(νx)!
T=4MeV(νe)!
µ=3T!

SN explosion
mechanism

Temperature ofinterior of SN• Many information will be extracted: pointing, explosion mechanism(SASI etc), neutronization burst, interior temperature by NC events,
instance of NS/BH formation

51

SK-Gd•Discovery of relic SN

neutrinos is expected by O(1)sensitivity improvement•0.1% Gd loading to tag
νe+p→e+n, Gd+n→Gd+γs•R&D in test tank and water

system construction going on•Start SK-Gd in a few yrs
200-ton test tank(240 50-cm PMTs)

New water system underconstruction

Filter tanks

Gd loadedwater tank52

SRN measurement in Hyper-K• Guaranteed signal to investigate the averaged SN

explosion, and the fraction of dim-SN and BH formation• ~100 SRN / 10 years (>17.5MeV) is expected53

Solar neutrino physics• Precision measurement of solar νe toAssuming the solar best fit parameters

Day/Night significance Upturn offor
spectrum

0 asym.* KamLAND
2Tank 10 years

12σ

6σ

4.9σ

Expected # of events / Mton year

study ~2σ tension between νe and reactorνe (CPT violation or ?)• Test various exotic scenarios by spectrum• ν astronomy• Time variation test w/ ~200νs/day• First measurement of hepν

1Tank 10-years
105

8B+hep (BP2004 SSM)
only 8B

104
103
102

8B+hep

10

8B

1
10-1
10-2
12

(tan2 θ , ∆ m2) = (0.38, 8.3 × 10-5)
SK-III energy resolution / 1.414

14

16

18

20
22
24
Energy threshold (MeV)

54

Final remark• Japan-based neutrino program will haverich physics with world-leading science
outputs• Direct test of GUT• Full picture of neutrino oscillations (CPV, massordering, and others)• Variety of ν astrophysics, telescope•Hyper-Kamiokande is the flagshipexperiment in the program• Ready-to-go design• Budget request is being issued in Japan

55