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.
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