Road Map of Neutrino Physics in Japan

Largely my personal view

Don’t take too seriously

K. Nakamura KEK NuFact04 July 30, 2004

Road Map of Neutrino Physics in Japan

•Ongoing–Super-Kamiokande–K2K–KamLAND

•Constructing–T2K @ J-PARC

•R&D–Hyper-Kamiokande–XMASS–FFAG for Neutrino Factory

•Proposed–KASKA

•Double decay exp.42

m39m

C Scientific American

T2K Phase I: Measurement of sin2 2θ13

sin 2θ13 νμ(CC+NC) Bean νe Osc’d νe Signal+BG0.1 11.1 11.1 123.2 145.5

0.01 11.1 11.1 12.3 34.5

2sin22θ13

Δm2

×1/20CH

OOZ

limitJHF

sensitivity

Expected signal for

OA 2deg 5yrs

sin2213=0.1

Sensitivity for 13

sin2213~0.006 (90%)

sinsin22221313 < 10 < 10-3-3 can be searched if syst err ~ few % can be searched if syst err ~ few %

0.5xsin2213

sin2213~0.018 (3)

3 CP sensitivity : ||>20o for sin2213>0.01 with 2% syst.

4MW, 540kt2yr for

6~7yr for

sinsin

2sin4 13

12212

EmACP

m212=6.9x10-5eV2

m322=2.8x10-3eV2

12=0.59423=/4

T2K-I 90%

no BGsignal stat only

(signal+BG) stat only

stat+2%syst.stat+5%syst.

stat+10%syst.

CHOOZ excludedsin2213<0.12@m31

2~3x10-3eV2

T2K 3 discovery

T2K: CP Violation Sensitivity

Possible Phase 2 Intensity Upgradeof the J-PARC 50 GeV Ring

Ramping speed → 0.89 HzLattice magnet designed this way

Barrier bucketDecreases the local line density at injectionReduces the space charge effect

2 detectors×48m × 50m ×250m, Total mass = 1 Mton

Twin Detector Hyper-Kamiokande

Wished Construction Plan

2008 09

20 10

11

12

13

14

20 15

16

17

18

19

2020

21

22

23

T2K-I

HK construction

HK experiment

9

Japanese FFAG Scheme

10

Nufact at J-PARC

11

Staging Approach towards Realization

Long Baselines ?

J-PARC

Seoul

Beijing

Fukuoka

ShanghaiOr Hawaii ?

13

Construction of the PRISM-FFAG

14

Pulsed proton beam facility

Road Map of Neutrino Physics in Japan

Neutrino CP

Violation(If >20 deg)

Measurement of 13

J-PARC

Hyper-K

T2K Phase IIJ-PARC

IntensityUpgrade

T2K Phase I

Measurement of sgn(m23

2 )

FFAG R&DNeutrino factory

If 13 is not too small (sin2213 > 0.02)

We are here.

Super-KK2KT2K

KamLANDKASKAXMASS

Precision measurements of m232, 23, m12

2, (12)

How can we discriminate positive and negative m2 ?

Real m2 = positive assumed

(No resonance for anti-neutrinos)

Real m2 = negative assumed

(No resonance for neutrinos)E(GeV)

cos

P(e)

E(GeV)

cos

P(e)

How can we discriminate neutrino and anti-

neutrino interactions ?

Simple answer: No. It is not possible to discriminate event by event in water Cherenkov experiments.

However, (total) and d/dy are different.

Try to discriminate positive and negative m2 using these events.

CC e

CC e

CC e

CC e

Others Others

Single-ring e-like Multi-ring e-like

Electron appearance for positive and negative m2

Single-ring e-like Multi-ring e-like

Positive m2

Negative Dm2

null oscillation

cos cos

Relatively high anti-e fraction

Lower anti-e fraction

m2=0.002eV2

s223 = 0.5 s213 = 0.05(SK 20yrs)

2 difference (inverted-normal)

m2: fixed, 23: free, 13: free

Exposure: 1.8Mtonyr (SK 80yr or HK ～ 3.3 yr)

3 3 3

True= normal mass hierarchy assumed.

2 difference (normal – inverted)

m2: fixed, 23: free, 13: free

Exposure: 1.8Mtonyr (SK 80yr or HK ～ 3.3 yr)

3 3 3

True= inverted mass hierarchy assumed.

We are here.

Super-KK2KT2K

90% CL Upper Limit of 13

J-PARC

T2K Phase I

Road Map of Neutrino Physics in Japan

J-PARC IntensityUpgrade

Measurement of 13

Hyper-K

T2K Phase II

Neutrino CP

Violation(If >20

deg,Sin2213>0.0

1)

FFAG R&D

Neutrino factory

If 13 is small (0.006 < sin2213 < 0.02)

Road Map of Neutrino Physics in Japan

We are here.

Super-KK2KT2K

13≠0 cannot be

established

J-PARC

T2K Phase I

J-PARC IntensityUpgrade?

Hyper-K?

T2K Phase II?

FFAG R&D

Neutrino factory

If 13 is too small (sin2213 < 0.006)

Road Map of Neutrino Physics in JapanSummary (Most Optimistic Case)

2004200520062007200820092010201120122013201420152016201720182019202020212022202320242025

K2K Super-K / Hyper-K T2K J-PARC 50 GeV FFAG R&D

finished Full reconstruction 　　　　 construction 　　 construction 　 completed completed low intensity

full intensity

Phase I

construction Phase 1.5

(CP)-

Phase IICP

Intensityupgrade

P decayAtmospheric

PRISM-I@J-PARC

PRISM-II@J-PARC

NeutrinoFactory ？