Takaaki KajitaInstitute for Cosmic Ray Research, Univ. of Tokyo

Sorry, but I will not discuss;• Non-standard explanations of oscillation experiments• Other types of experiments related to neutrino masses

and mixings (ββ, 3H, …)• Other neutrino experiments….

• Introduction (very short)• Solar neutrino experiments and KamLAND• Atmospheric neutrino experiments• K2K• LSND and MiniBOONE (very short)• Future neutrino oscillation experiments• Summary

O u t l i n e

−⋅

⋅

−⋅

−=

=

−1313

1313

2323

23231212

1212

321

321

321

0010

0

00010001

00

001

10000

cs

sc

ecssccs

sc

UUUUUUUUU

Ui

eee

δτττ

µµµ

ilil U νν Σ=Neutrino MixingWeakeigenstates

Masseigenstates

νe νµ ντNormal mass hierarchy assumed:

ν3

ν2ν1

Solar,

KamLAND

Atmospheric

Long baseline

(future)LBLReactor

small

(future)Super-beamNeutrino factory

Ga 37Cl

GALLEX(+GNO)

Homestake

Theory7Be

8B

pp, pep

CNO

ExperimentsH2O

SuperK Kamiokande

SAGE

Before SNO….

SK day-night, spectrum data included

GNO Homewstake

Kamiokande

G.L.Fogli et al.

LMASMA

LOW

tan2θ12

SNO

NCxx νν ++→+ npd

ES -- +→+ eνeν x x

CC -eppd ++→+ν e

- νe ONLY

- Equal cross section for all ν types

Mainly sensitive to νe, less to νµ and ντ

1,000ton D2O

8Β ν Reactions in SNO

n + d → t + γ (Eγ = 6.25 MeV)(pure D2O phase)

SNO results in 2002

0 1 2 3 4 5 60

1

2

3

4

5

6

7

8

)-1 s-2 cm6

(10eφ

)-1

s-2

cm

6 (

10τµφ SNO

NCφ

SSMφ

SNOCCφSNO

ESφ

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6νe flux (106 /cm2/sec)

ν µ+ντ fl

ux (1

06 /cm

2 /sec

)

1σ2σ3σ

SSM ±1σ

SK SNO CC

SNO NC

(5.3σ) (5.5σ)

If Super-K data (ES) are used:

OR

Evidence for νµ or ντ appearance

SNO

Neutrino oscillation parameters (summer 2002)

hep-ph/0206162

SMA solution excluded at > 3σ

LOW is disfavored at 99%.

LMA is OK.

1,000ton liquid scintillator detector

Thermal power ~ 80GW<E> ~ 3 MeV<base line> ~ 180 km

KamLAND results

0

25

20

15

10

5

086420

Prompt Energy (MeV)

2.6 MeVanalysis threshold

KamLAND data no oscillation best-fit oscillation

sin22θ = 1.0 ∆m2= 6.9 x 10-5 eV2

Ev

ents

/0.4

2

No osc.

νe - νµ, τ osc.

Confirmation of the LMA solution

θ22sin0 0.2 0.4 0.6 0.8 1

)2 (

eV2

m∆10

-6

10-5

10-4

10-3

Rate excludedRate+Shape allowedLMAPalo Verde excludedChooz excluded

86.8±5.6 events expected54 observed (0.95±0.99 BG)

(145 days)

KamLANDallowed

hep-ex/0212021

Neutrino oscillation parameters: Solar + KamLAND

G.L.Fogli et al.

Holanda,Smirnovhep-ph/0212270

CC/NC Ratio(8B)

Distinguishing LMA-I and –II

Day-night asym. (%)

(8B νe flux)

0123456789

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1tan2Θ

∆χ

2

1 σ

2 σ

3 σ

∆m2 in 10-5eV2

∆χ

2

1 σ

2 σ

3 σ

0123456789

0 2 4 6 8 10 12 14 16 18 20

New analysis results from Super-Kamiokandemax. likelihood analysis (hep-ex/0309011)

+1.3ADN=-1.8±1.6 %-1.2

(@LMA-I)

SK-new analysis + solar + SNO(2002) + KamLAND

LMA-II

LMA-II is disfavored at about 99%CL (2 parameter region).

0.45

0.5

0.55

0.6

0.65

0.7

0.75

Da

ta/S

SM

LMA best-fit Spectrum

E in MeV

Asym

me

try in

%

LMA best-fit D/N Asymmetry

±1σ

-50

-40

-30

-20

-10

0

10

6 8 10 12 14 16 18 20

±

25% smaller

X 1/3X 0.45

~ 9 NHIT/MEV

NC (salt)

NC (Pure D2O)

SNO salt phase2 tons of NaCl added into 1000 ton D2O

(Salt phase: 2001-2003)

NCxx νν ++→+ npd

- Equal cross section for all ν types

n + Cl → Cl + γ‘s (ΣEγ = 8.6 MeV)

◆Higher neutron capture rate

◆Higher total energy release

◆Isotropic signal (many gammas)

WG discussion J.Formaggio

New results from SNO

(MeV)effT6 7 8 9 10 11 12 13 14

Eve

nts

per

500

keV

0

100

200

300

400

500

600

(c)

neutrons

CC ES

Electron energy

)(024.0)(026.0306.0 syststatNC

CC ±±=φφ

×0.6 of Pure D2O

×0.85 of Pure D2O

254 days

Nucl-ex/0309004

Oscillation analysisSNO(2003)+KamLAND+solar (Sep.2003)

θ2tan10

-11

90% CL95% CL99% CL99.73% CL

(b)LMA-II disfavored at >99%CL

Full mixing for θ12excluded at 5.4σ

)%68(5.32

1.75.24.212

22.16.012

2

CLeVm

==∆

+−

+−

θ

SNO nucl-ex/0309004

Cosmic Ray

π, K

νµ eνµ νe

Atmosphere μ

Neutrinos from the other side of the Earth.

νµ

νe

SK atmospheric neutrino data (reanalyzed, still prelim.)

1489day FC+PC data + 1646day upward going muon data

1-ring e-like 1-ring µ-like multi-ring µ-like up-going µ

Up-going Down-going

No osc.

Osc.

stopping

Through going

< 1.3GeV

> 1.3GeV

050

100150200250300350400450

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Sub-GeV e-like

0

100

200

300

400

500

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Sub-GeV µ-like

0

20

40

60

80

100

120

140

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Multi-GeV e-like

0

50

100

150

200

250

300

350

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Multi-GeV µ-like + PC

05

101520253035404550

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Sub-GeV Multi-ring

0

0.2

0.4

0.6

0.8

1

1.2

1.4

-1 -0.8 -0.6 -0.4 -0.2 0cosθ

Flu

x(10

-13 cm

-2s-1

sr-1

) Upward Stopping µ

0

20

40

60

80

100

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Multi-GeV Multi-ring

0

0.5

1

1.5

2

2.5

3

3.5

4

-1 -0.8 -0.6 -0.4 -0.2 0cosθ

Flu

x(10

-13 cm

-2s-1

sr-1

) Upward Through Going µ

Neutrino oscillation parameters

10-4

10-3

10-2

10-1

0 0.2 0.4 0.6 0.8 1

sin22θ

∆m2 (

eV2 )

νµ→ντ

(90%CL)

Soudan-2

MACRO

Kamiokande

Super-K

>×<∆< −

90.02sin)(100.33.1

2

232

θeVm

(90%CL)

Improvements and sub-sample consistency (SK)

10-4

10-3

10-2

0 0.2 0.4 0.6 0.8 1 1.2sin22θ

∆m2 (

eV2 )

Combine

Sub-GeV lowSub-GeV highMulti-GeVPCMulti-ringUp µ

90% CL

• ν flux(1dimensional 3d.)

• Event reconstruction

• ν interaction models(based on K2K near data)

• Detector simulation

Each change contributes to the shift in the allowed (∆m2) region.

Improvements

WG discussion (E.Kearns)

Eν(GeV)

Neutrino oscillation probability for Δm2=0.003eV2 and at 250km.

250km

Event selection

1

10

10 2

10 3

-500 -250 0 250 500

FC

∆(T) µs

even

ts

∆(T) µs

even

ts

0

5

10

15

20

-5 0 5

Tspill TSK

GPS

HE Trig.

fully contained 22.5kt fiducial volume

1.5µs

±500µsec

±5µsec∆T (µsec)

∆T (µsec)

Atmν BG

number of events56 observed80.1 expected

null oscillation prob. 1.3%

+6.2- 5.4

ν

Expected arrival time of ν

0.48×1019p.o.t. (1999-2001)(1/2 of the proposal)

Oscillation vs. data

★KS test prob.(Eν dist): 79%

Best fit point (sin22θ , ∆m2)= (1.0, 2.8×10-3eV2)

★NSK(expected by osc.)=54NSK(observed)=56

Both NSK and Eν-distribution are consistent with oscillations.0

1

2

3

4

5

6

7

8

9

10

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Eν

rec

Even

ts

Best fit

Normalized by area

No osc.

Eν(reconstructed) (GeV)

Num

ber o

f eve

nts

CC quasi elastic reaction Eν from (Eμ and θμ)

Allowed parameter region based on Eν and NSK

10-4

10-3

10-2

0 0.2 0.4 0.6 0.8 1sin22θ

∆m2 (eV

2 )

68%90%99%

10-1

K2K and atmospheric neutrino data are consistent.

νµ - ντ

10-4

10-3

10-2

10-1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

68% C.L.90% C.L.99% C.L.

sin22θ∆m

2 (eV

2 )

K2K Super-K

FC 22.5kt

POT vs events

KS probability = 64.3%

CT *1018 POT

even

ts

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60

1999 2000 2001 2003

K2K-I + II Preliminary

New K2K data after SK recovery

K2K-I80.1+6.2

-5.4 expected56 observedobs/exp=0.70±0.09(stat)

K2K-II (until April 2003)26.4+2.3

-2.1 expected16 observedobs/exp=0.61±0.15(stat)

Event rates are consistent between K2K-I and -II

SK reconstruction work in 2002

K2K-IIK2K-I

θ13 ?

Xe νν →

～ 1km

Atmospheric neutrinos

Matter effect

250km

eνν µ →Long baseline exp.

Reactor exp.

)27.1(sin2sinsin

)(

)27.1(sin2sin

)(

22

132

232

22

132

ν

µ

ν

θθ

νν

θ

νν

ELm

P

ELm

P

e

Xe

∆⋅⋅=

→

∆⋅=

→

=0.50±0.16

∆m212=0

assumed

050

100150200250300350400450

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Sub-GeV e-like

0

100

200

300

400

500

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Sub-GeV µ-like

0

20

40

60

80

100

120

140

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Multi-GeV e-like

0

50

100

150

200

250

300

350

-1 -0.5 0 0.5 1cosθ

Num

ber

of E

vent

s Multi-GeV µ-like + PC

Data

SK Atmospheric neutrinos

K2K electron appearance

CHOOZ νedisappearance

all data

0

50

100

150

200

250

300

0 2 4 6 8 10

MC

ν signal

e+ energy

MeV

0.35νe BG2.0νµ BG

2.4BG1Data

(ε=55%)

No evidence for non-zero θ13

Constraints on θ13

=0.5・sin22θ13

SK atm.

K2K νe appearance

CHOOZ νedisappearance

(Similar but slightly weaker constraint from Palo Verde)

hep-ph/0308055

New SK atm. data used

Old SK atm. data used

Lower ∆m2 and global analysis

K.Nishikawa LP03

(old analysis)

LSND and MiniBooNE

LSND

If LSND result is confirmed, it could be a real new physics. (No one can explain LSND within the presently known frame work of neutrino oscillations.)

Very important to check the LSND results.

MiniBooNEνµ event (real)

MiniBooNE taking data since Aug.2002. (ν WG H.Tanaka)

flux

• Known;∆m2

23(13), θ23, ∆m2

12, θ12 and the sign of ∆m212

• Unknown; θ13 (known to be small), δ(CP phase), sign of ∆m2

23(13)

Need experimental confirmation; Oscillation τ appearance

Status

JPARC-nu

WG discussions

730km

Far detector constructed, atmospheric neutrino run since summer 2003

=sin2θ13

MINOS sensitivities

MINOS (start end 2004)

CNGS (start 2006)Primary goal: detection of tau neutrinos

OPERA ICARUS

3.0 kton liq. argon detector

T600 data in 2001

Emulsion layers

Hybrid emulsion detector (1.7kton)

Observe τ decay

Bubble chamber like image

Detailed kin. study of ντevents

0.730.511.94.9ICARUS0.6526.310.34.3OPERA

background4.0・10-32.5・10-31.6・10-3(5yrs)

732km

Expected number of τ events

JPARC neutrino project (start 2008 or 9?)

295km

×100 more intensity than K2K, Eν < 1GeV

102

103

104

105

106

107

0 1 2 3 4 5Eν (GeV)

Flu

x (/

100M

eV

/cm

2/y

r)

Max. osc. Eνfor 0.003eV2

OFF-axis 2deg.

θTarget

Horns

Decay Pipe

2.5±0.5゜

Off-axis beam

×20

0.5・sin22θ13

10-4

10-3

10-2

10-1

10-3

10-2

10-1

1

90% C.L. sensitivities

JHF 5yearOAB 2deg.

CHOOZ excluded

sin22θµe

∆m2 (

eV2 )

θ13 sensitivityJPARC sensitivity (5yrs)

sin22θ23

Status: waiting for decision (approval?) at the end of this year

SK

JPARC

νµ νe

NuMi Off-axis (year ?)

Possible sites

Neutrino oscillation experiment with an Off-Axis detector (lower energy neutrinos)

Detector:40kton fiducial massLow Z, high granularity detector

Similar sensitivity as JPARC-ν

0

1

2

3

4

5

6

∆m2

atm > 0

∆m2

atm < 0

ENuMI = 1.5 GeV

(a)

50

40

30

35

25

50

40

35

30

25

EJHF = 0.6 GeV

0 1 2 3 4 50

0

JHF P

NuMI

Matter effect: MuNi-Off-axis > JPARC

P(νµ νe, JPARC)[%]P

(νµ

ν e, N

uMi)[

%]

Determine the sign of ∆m2

hep-ph/0301210

Importance of understanding of neutrino interactions

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 1 2 3 4 5Eν (GeV)

cro

ss s

ectio

ns (1

0cm

)-3

82

Inelastic

CCqe

JPARC

Muni-Off-axis

QE + non-QE

Non-QE

No osc.Oscillation (sin22θ23=1.00)

QE events only

(JPARC) Stat. error: +/- 8.5

Non-QE BG: 43

20% syst. In non-QE/QE ratio = 8.5 events

Non-QE/QE ratio must be understood (much) better than 20%.

Example:

WG discussion

For sin22θ23=1.00

Reactor experiments for θ13 (Do better than CHOOZ did)

Good: Relatively cheep(?),If measured, the measurement is really a measurement of θ13

(No ambiguity from θ23, sign of ∆m2, CP phase)

Challenge: disappearance (% range) control systematics <1%, higher stat.2 (identical) detector system, ～50tons eachunderground

Serious discussions in Russia, USA, Europe and Japan

Factor 5-10 improvement seems possible

One possible site …

About 2km

Toward the measurement of δ(CP phase)Super-beam experiments

4MW, 2.2GeV SPL (Superconducting Proton Linac) @CERN

130 km

Ability to see maximal CP violation

BNL

Hyper-K (1Mton)

Neutrino factories based on µ storage ring

• In the past several years, we have learned a lot about the neutrino masses and mixings.

• We know ∆m223(13), θ23, ∆m2

12, θ12 and the sign of ∆m2

12 .• In the future neutrino oscillation experiments, yet

unknown oscillation parameters (θ13, δ, and sign of ∆m2

23(13) ) can be measured.