Future Long-baseline
Neutrino Oscillations~ View from Asia ~Yoshinari Hayato( Kamioka, ICRR, UTokyo )Used material in this presentation
Kindly Provided by
J-PARC accelerator group,
KEK neutrino group,
Hyper-Kamiokande working group, andMOMENT group.

Neutrino mixing parameter measurements
Normal hierarchy

Inverted hierarchy−𝟑𝚫𝐦𝟐𝟐𝟏 = 𝟕. 𝟒𝟗+𝟎.𝟏𝟗
eV/c 𝟐−𝟎.𝟏𝟕 × 𝟏𝟎𝚫𝒎𝟐𝟑𝟐~𝟐. 𝟓 ± 𝟎. 𝟐 × 𝟏𝟎−𝟑 eV/c 𝟐𝟐𝚫𝒎𝟐𝟑𝟐~𝟐. 𝟓 ± 𝟎. 𝟐 × 𝟏𝟎−𝟑 eV/c 𝟐−𝟑 eV/c 𝟐𝚫𝐦𝟐𝟐𝟏 = 𝟕. 𝟒𝟗+𝟎.𝟏𝟗−𝟎.𝟏𝟕 × 𝟏𝟎𝟐𝟐sin2q12 ~ 0.305±0.013
sin22q13 = 0.098 ± 0.013

Remaining questions
1) q23 is really 45o or < 45o or >45o ?
Current uncertainty of sin2q23 is still large ~ 10% levelsin2q23 = 𝟎. 𝟓𝟏𝟒 ± 𝟎. 𝟎𝟓𝟓 ( T2K 2014 )2) CP is violated or not ( d = 0 or not ) ?
23) Mass hierarchy ~ which is heavier ? ( Dm232 > 0 or < 0 ?)𝟐

Recent results from Reactor & T2K
ne appearance clearly observedin T2K
Reconstructed n energy
DataBest fit
No oscillation

Allowed region of δCPfor each sin22θ13Extracted sin22q31 is slightly larger thanthe ones from reactor experiments
sin22q13 =0.140+0.038−0.032 ( normal hierarchy )0.170+0.044−0.037 ( inverted hierarchy )Indication of non-zero dCP?

3

Neutrino experiments & related facilities in Asia
KamLAND

SuperK

RENO50Daya BayJUNO /MOMENT

RENO

Hyper-Kamiokande

J-PARC

INO

4

J-PARC neutrino beam
& Hyper-Kamiokande5Hyper-Kamiokande with J-PARC neutrino beam
Hyper-Kamiokande( Total volume ~ 1M ton )J-PARC Main Ring
Neutrino beamline( KEK – JAEA )J-PARC neutrino beam line
One of the most powerful beamlines in operationand further intensity upgrade ( >750kW ) is undergoing.
Hyper-Kamiokande
World largest water Cherenkov detector ( fid. vol. 560 kt. )Powerful combination
to search for the lepton sector CP violation! 6

Hyper-Kamiokande with J-PARC neutrino beam
J-PARC Accelerator & neutrino beamline
Proton intensity up to 750 kW has been planned
from the beginning.
Expected to achieve in 3 years.
Further upgrade ( > 1MW ) is under study.
All the beamline components are designed to accept full 750 kW beam.
Some unreplaceable components are designed to accept > MW beam.

7T. Koseki@1st Hyper-K meetingHyper-Kamiokande with J-PARC neutrino beam
Off-axis narrow band n / n̅ beam
Optimized for the neutrino oscillation experiments in Kamioka.
( Both for SK and Hyper-K. )n modeSKn beamfrom J-PARC~ 8 kmHKDesigned to have sameoff axis angle at both sites.

n̅ modeSmall ne / n̅e backgroundaround the flux peakosc. max.

8

Hyper-Kamiokande with J-PARC neutrino beam
Off-axis narrow band beam
Extensive studies have been performed to understandthe characteristics of the neutrino beam.
1) Dedicated hadron production experiments( as a part of NA61-Shine )2) With ND280 measurements,
uncertainties on the ratio( near/far ratio ) isless than 2%near the flux peak.
& Further reduction is expected.
2) Established beam monitoring scheme.
Primary, secondary ( m ) and n themselves.
9
Properties of the neutrino beam is well understood.

Hyper-Kamiokande
Far detector “ Hyper-Kamiokande”
What is not sufficient in SK? => ~ Statistics = target mass ~1Mton Water Cherenkov detector
HK : Fiducial volume560 kton ~ 25 x SK
( 48m x 54m x 250m )Photo coverage : 20%( 99,000 20 inch Photo sensors )Maximum utilization of resources and experiences in SK~ Use established technology for the long term operationto achieve physics goal in timely manner.
Broad science programs
1) Accelerator neutrinos from J-PARC
2) Atmospheric, Solar, Super Nova and cosmic neutrinos
3) Nucleon decay searches etc….

10Physics in Hyper-KamiokandeNeutrino oscillation• Accelerator neutrinos• Atmospheric neutrinos• Solar neutrinos
Proton decay search ~ GUT
Possible discovery with ~10 times
better sensitivities than SK
p → e+ + p0 : ~ 5.7 x 1034 years( 3s )+34
p → K + n̅ : ~ 1.2 x 10 years
Neutrino astrophysics• Super nova burst neutrino
Expected ~200,000 n eventsfrom SN @ 10kpc• Relic SN neutrinos
Expected several hundredsof events

11

Hyper-Kamiokande with J-PARC neutrino beam
Water Cherenkov detector• Well established technology
Past experiences in the long term operation~ Need O(10) years of operation ~• Continuous improvements in the data analysis( Event reconstruction & background rejections )One particular example ~ New p0 rejection method ~p0 used to be one of the dominant background sources
Reconstructed p0 mass vs likelihoodin ne appearance search.
In the latest T2K analyses,
only 23% is coming from p0s!
*) 74% of background events
are beam intrinsic ne.
12Hyper-Kamiokande project
Selected one of the 27 ‘top projects’in ‘Japanese master plan for large scale research projects’
by Science Council of Japan
International working group was formed ( http://www.hyperk.org )~ Wide variety of physics attracts many people from the world ~Next open meeting : July 19-22, 2014 in Vancouver
http://indico.ipmu.jp/indico/conferenceDisplay.py?confId=34
12 countries, 67 institutes, 240 people

13Hyper-Kamiokande detector
Is it possible to construct such gigantic detectors?
Candidate site : Tochibora mine in Kamioka

Design of the cavern
and its supporting structures

Based on the geological survey and analyses,
the cavern and the supporting structures were designed.
Possible to construct HK Caverns with existing technology. 14

Hyper-Kamiokande detector
Design of the detector structure
Incl. PMT supports

Schematic diagramof water purification system
for HK detector

Baseline design of the detector is finishedbased on the past experiences in SK.15

Hyper-Kamiokande detector ~ Further improvements ~Photo sensors ~ R&D to improve the detector performance
Better timing resolution ~ better vertex resolution
Higher quantum efficiency
Baseline ( reference )Candidates ( R&D phase )Quantum eff.

22%

30%

30%

Collection eff.

80%

93%

95%

5.5 nsec

2.7 nsec

1 nsecTiming res. ( FWHM )16

Hyper-Kamiokande detector ~ Activities in the world ~USA ~ New PMT R&DCanada
Photo sensor test facility

Europe & Canada~ Near detector designs
TITUS
nPRISM

Network I/O module study

UK DAQ system, HPD/LAPPD, Calibration system R&D etc..

17

Hyper-Kamiokande project ~ Notional Timeline ~18

Neutrino physics of LBL J-PARC & HK ~ Determination of CP d
CP-non conservation term in osc. prob. ∝ sinq13sind ( sin22q ~ 0.1 )13（ sign of d for anti-neutrino is different from neutrino )Oscillation prob. for nm → ne @ 295km( Normal hierarchy )Hyper-Kamiokande + J-PARC neutrino beam~ 3000 ne & ~ 2000 n̅e signal events are expected, when d = 0( 7.5 x 107 MW·sec )Measurements of d by comparing oscillations of n andn.
At maximum CP violation, ~25% difference from d=0 19case.

Neutrino physics of LBL J-PARC & HK ~ Determination of CP d
• Expected # of events for sin22q13 = 0.1, d = 0 and NH( 7.5 x 107 MW·sec )NC ( p0 ) is not the dominant background already.

• Reconstructed energy of neutrino for candidate events
Neutrino mode beamAnti neutrino mode beam

20

Neutrino physics of LBL J-PARC & HK ~ Determination of CP d
Systematic error Errors used in the sensitivity studies~ Realistic estimation of the errors based on the experiences ~Reduction of errors in the XSEC models
New measurements of neutrino interactions
Improved theoretical modeling
Reduction of errors in the far detector + Final state interactions
Increased statistics of atmospheric n control sample in HK
New near ( intermediate ) detectors with H2O target( incl. Water Cherenkov detector )21

Neutrino physics of LBL J-PARC & HK ~ Determination of CP d
Use both # of observed eventsand reconstructed energy spectra of n andn.
( @ 7.5 x 107 MW·sec , n :n = 1 : 3 )Normal mass hierarchy

Inverted mass hierarchy

Determination power of CP d parameter1s error of d is expected to be 8o ~ 19o.

22

Neutrino physics of LBL J-PARC & HK ~ Determination of CP d
Sensitivity ~ Exclusion of sind = 0( 7.5 x 107 MW·sec )Hierarchy is assumed to be known

Fraction of d~ Exclusion of sind = 0Hierarchy is assumed to be known

Normal hierarchy

Exclusion of sind = 076% of d at 3s level and 58% of d at 5s levelwith realistic systematic error estimations.
23

in HK
Neutrino physics ofLBL J-PARC & HK
~ Measurements of | Dm232 | and sin22q23( 7.5 x 107 MW·sec )Expected precisions ( 7.5 x 107 MW·sec )True Dm232 = 2.5 x 10-3 eV2
0.55
True sin2q23 = 0.50 ( Full mixing )0.45( T2K 2014 results±0.015 × 10−3 eV 2 ( 0.6% )±0.009 ( 1.6% )±0.015 ( 3% )±0.006 ( 1.3% )Dm232 = 2.51 ± 0.10 × 10−3 eV 2
sin2q23 = 0.514 ± 0.055)

24
Large improvements & good chance to identify non-maximal mixing.

MOMENT~ a muon decay medium baseline neutrino facility ~25

MOMENT ~ a muon decay medium baseline neutrino facility
Future accelerator based neutrino oscillation experiment in China
Intended to study CP violation in the lepton sector
Lowering the energy to largely reduce backgrounds
from pion productions.
Planned baseline is ~ 150km
Mean beam energy is tuned ~ 240 MeV.
Neutrino beam from muon decays( Conventional neutrino beamuses n from pion decays )Expected neutrino flux
( Depends on the level ofthe pion capture field at target )14T Field : 4.7 x 1011 n/m2/year( 7T Field : 2.1 x 1011 n/m2/year )26

MOMENT ~ a muon decay medium baseline neutrino facility
Use extremely intense proton beam ( 15MW )from CW Superconducting LINAC
Accelerator : Use the same technology but different design
for China-ADS (a funded R&D project)
Pion target
Mercury jet or
fluidized
tungsten powder
Detector : * Need charge identification *Various possibilities are considered
Water Cherenkov detector with Gd ( like GAZOOKS )Magnetized Iron detector ( MIND )27
Magnetized liquid Argon detector

Summary~ It’s time to start new experiments
to explore CP violation in the lepton sector. ~J-PARC neutrino beam with Hyper-Kamiokande• Utilize existing intense neutrino beamline with upgrades~ Well understood and under control.

• Feasible Gigantic Water Cherenkov detector
Established detector technology ~ Feasible
Proven excellent performance in physics analyses
Proven long term stability

Further reduction of the cost& performance improvements
Realized by new technology and analysis methods( Will be confirmed with the test detectors and SK. )Broad physics opportunities
Various sources of neutrinos, nucleon decay etc..

MOMENT ~ a muon decay medium baseline neutrino facility
Different configuration of a new experiment witha new design of intense neutrino beam production

28

Fin.

Introduction
Neutrino oscillation ~ discovered in 1998 & extensively studied.
Flavor mixing & non-zero neutrino mass
~ Beyond the standard model ~• 3 oscillation angles(q12, q23, q13)
• 2 mass differences(Dm212, Dm232)• 1 CP phase (d)Parameters

PMNS Matrix (Uai)|na> = SUai|ni>
Weak

Mass eigenstates

sij=sinqij, cij=cosqij

U=Atmospheric& Accelerator

Reactor& Accelerator

Solar& Reactor30

64 2s2Neutrino oscillation parameter measurements
2-5

Dm in 10 eV2( Atm. + Accl. )1s| Dm232 | & sin22q23

18171615141312111098765432(Solar + Reactor)
Dm221 & sin2q12

KamLAND0.1( Reactor + Accl. )Solar νexperiments

1s0.20.3

0.40.52sin (q12)

Dm221 = 7.49 +0.19-0.17 x10-5(eV/c2)2| Dm232 | ~ 2.5 ± 0.2 x 10-32)2(eV/c
sin22q23 > 0.9
sin2q12 ~ 0.305±0.013
sin22q13 = 0.098 ± 0.013
sin22qDaya-Bay collab. PRL 112 (2014) 061801
sin22q13 = 0.090+0.00831-0.00913

Next step ~ Prospects of the current experiment· Current generation experiments( T2K and NOvA ) are expected to leadthe study of the CP violationin the lepton sector.

Region where sind=0
can be excluded by 90% C.L.
Normal hierarchy
Red T2K alone
Blue NOnA alone Black T2K + NOnA

· However, the expected sensitivityof CPV is ~ 2s level

Next generation experiments
are essential
for the study of CPV
and mass hierarchy
Both T2K / NOnA : full POT ( POT fraction : 50% n + 50% anti-n)Assuming 5% (10%) normalization uncertainty on signal (background)
Assuming true: sin22q13=0.1, Dm232=2.4×10-3 eV232
q13 constrained by d(sin22q13) = 0.005

Excerpts from the P5 report
For a long-baseline oscillation experiment, based on the science
Drivers and what is practically achievable in a major step forward,
we set as the goal a mean sensitivity to CP violation of better than
3σ (corresponding to 99.8% confidence level for a detected signal)
over more than 75% of the range of possible values of the unknown
CP-violating phase dCP.

Sensitivity of d

76% ( 3s ) of the d is coveredby J-PARC + Hyper-Kamiokande

33Sensitivity of proton decays

34

Dm221=7.6x10-5eV2

Osc. prob. (nm→ne)

0.1

Oscillation prob. for nm → ne @ 295km|Dm232|=2.4x10-3eV2
sin2q12=0.31
sin2q23=0.5
r=2.6g/cm3

00.6

1

En (GeV)

Hierarchy is assumed to be known( 10 yrs )35