Takaaki Kajita Institute for Cosmic Ray Research, Univ. of Tokyo O u t l i n e • Introduction (very short) • Solar neutrino experiments and KamLAND • Atmospheric neutrino experiments •K2K • LSND and MiniBOONE (very short) • Future neutrino oscillation experiments • Summary
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…. µ ν µ τ µ = Σ ν Neutrinoτ Mixing l Uli i τ Weak Mass eigenstates eigenstates small
U U U c s 0 1 0 0 1 0 0 c 0 s e1 e2 e3 12 12 13 13 = = − ⋅ ⋅ ⋅ U U 1 U 2 U 3 s12 c12 0 0 c23 s23 0 1 0 0 1 0 − −iδ − U 1 U 2 U 3 0 0 1 0 s23 c23 0 0 e s13 0 c13
ν νµ ντ ν e Normal mass 3 hierarchy assumed: ν ν2 1 (future) (future) Solar, Atmospheric Super-beam LBL KamLAND Long baseline Neutrino factory Reactor Before SNO…. Theory 7Be pp, pep 8B CNO
Experiments G.L.Fogli et al. Ga 37Cl H2O
LMA SMA
SK day-night, LOW spectrum data included
SAGE GALLEX Homes Super (+GNO) take K KamiokandeKamiokande
GNO Homewstake 2θ tan 12 SNO 8Β ν Reactions in SNO
- CC ν + + + e d → p p e ν - e ONLY
ES + - + - νx e → νx e
Mainly sensitive to ν , ν e less to νµ and ντ
NC + + +ν x d → p n x
n + d → t +γ(Eγ = 6.25 MeV)
(pure D2O phase)
- Equal cross section for all ν types 1,000ton D2O SNO results in 2002 8
7If Super-K data (ES) are used: )
-1 SNO SNO
s 8 φ φ 6 ES CC -2 SNO OR /sec)
2 SNO 7 SK cm 5 6
/cm σ CC 6 6 3 (10 τ 4 σ µ 5 2 φ φSNO σ NC 1
4 flux (10 τ 3 φ ν SSM + 3 µ
ν SNO 2 2 NC 1 1 0 SSM ±1σ 0123456 0 0123456 φ 6 -2 -1 ) ν 6 2 e (10 cm s e flux (10 /cm /sec)
(5.3σ) (5.5σ)
Evidence for νµ or ντ appearance Neutrino oscillation parameters (summer 2002)
hep-ph/0206162 LMA is OK.
SMA solution excluded at > 3σ LOW is disfavored at 99%. Thermal power ~ 80GW
42 -3 25 2.6 MeV KamLAND data 10 analysis threshold no oscillation best-fit oscillation 20 2 θ Events/0. sin 2 = 1.0 2 -5 2 ∆ m = 6.9 x 10eV ) -4 15 2 10
No osc. (eV 10 2 m
∆ -5 5 10 Rate excluded Rate+Shape allowed 0 LMA 0 2 4 6 8 Palo Verde excluded -6 Chooz excluded Prompt Energy (MeV) 10 0 0.2 0.4 0.6 0.8 1 2 θ ν ν sin 2 e - µ, τ osc. Confirmation of the LMA solution Neutrino oscillation parameters: Solar + KamLAND
G.L.Fogli et al. Holanda, Distinguishing Smirnov hep-ph/ LMA-I and –II 0212270
Day-night asym. (%)
8 ν ( B e flux) CC/NC Ratio (8B) 2
New analysis results ∆χ from Super-Kamiokande σ 93 8 7 max. likelihood analysis (hep-ex/0309011) 6 5 42 SK-newσ analysis + 3 0.75 LMA best-fit Spectrum 2 11 solarσ + SNO(2002) 0.7 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0.65 + KamLAND 2 Data/SSM tanΘ
0.6 2 0.55 ∆χ 0.5 0.45
% 93 σ LMA-II 8 7 10 6 5 0 42 σ ± 3 -10 ±1σ 2 11 σ -20 0 Asymmetry in 0 2 4 6 8 101214161820 -30 2 -5 2 ∆ -40 LMA best-fit D/N Asymmetry m in 10eV -50 6 8 10 12 14 16 18 20 E in MeV LMA-II is disfavored ± +1.3 at about 99%CL ADN=-1.8 1.6-1.2 % (2 parameter region). 25% smaller (@LMA-I) SNO salt phase Î WG discussion J.Formaggio
2 tons of NaCl added into 1000 ton D2O ν (Salt phase: 2001-2003)
NC + + +ν X 0.45 x d → p n x X 1/3 n + Cl → Cl +γ‘s (ΣE = 8.6 MeV) γ NC (salt) - Equal cross section for all ν types
◆Higher neutron capture rate ◆Higher total energy release NC (Pure D2O) ◆Isotropic signal (many gammas) ~ 9 NHIT/MEV New results from 600 (c) SNO 500 254 days 400 Nucl-ex/0309004 neutrons Events per 500 keV 300
200
100 CC ES
0 6 7 8 9 10 11 12 13 14 T (MeV) Electron energy eff
×0.6 of ×0.85 of Pure D O 2 Pure D2O
φ CC = 0.306± 0.026(stat) ± 0.024(syst) φ NC Oscillation analysis SNO(2003)+KamLAND+solar (Sep.2003)
(b) SNO nucl-ex/0309004 LMA-II disfavored at >99%CL
θ Full mixing for 12 excluded at 5.4σ 90% CL 95% CL ∆ 2 = +1.2 2 m 12 7.1−0.6 eV 99% CL + (68%CL) θ = 2.5 99.73% CL 12 32.5−2.4 -1 10 1 tan 2θ Cosmic Ray
π, K Atmosphere μ
νµ e ν µ ν e
νµ ν e
Neutrinos from the other side of the Earth. 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 Sub-GeV e-like Sub-GeV µ-like Sub-GeV Multi-ring Upward Stopping µ 450 50 ) 1.4 500 45 -1 400 sr 1.2 40 -1 350 s stopping 400 35 -2 1 300
30 cm 250 0.8 300 25 -13 200 20 0.6 200 Number of Events Number of Events 150 < 1.3GeV Number of Events 15 0.4 100 10 Flux(10 100 0.2 50 5 0 0 0 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 -1 -0.8 -0.6 -0.4 -0.2 0 cosθ cosθ cosθ cosθ Multi-GeV e-like Multi-GeV µ-like + PC Multi-GeV Multi-ring Upward Through Going µ 350 ) 4 140 100 -1 300 sr 3.5 No osc. -1 120 s 3 Through 250 80 -2 100
cm 2.5 going 200 60 80 -13 2 150 60 40 1.5 Number of Events Number of Events 40 Number of Events 100 Osc. 1 20 Flux(10 20 > 1.3GeV 50 0.5 0 0 0 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 -1 -0.8 -0.6 -0.4 -0.2 0 cosθ cosθ cosθ cosθ Up-going Down-going
Neutrino oscillation parameters
-1 (90%CL) 10 ) 2 νµ→ντ (eV
2 Kamiokande
m Soudan-2 ∆ -2 10
Super-K 2 −3 2 -3 1.3 < ∆m < 3.0×10 (eV ) 10 2 θ > MACRO sin 2 0.90 (90%CL)
-4 10 0 0.2 0.4 0.6 0.8 1 sin22θ Improvements and sub-sample consistency (SK)
90% CL ) Improvements 2 (eV 2
ν m
• flux ∆ (1dimensional Î 3d.) -2 • ν interaction models 10 (based on K2K near data) • Detector simulation Combine • Event reconstruction -3 10 Sub-GeV low Sub-GeV high Multi-GeV PC Each change Multi-ring contributes to the Up µ -4 10 shift in the allowed 0 0.2 0.4 0.6 0.8 1 1.2 2 (∆m2) region. sin 2θ WG discussion (E.Kearns) 250km
Neutrino oscillation probability for Δm2=0.003eV2 and at 250km.
Eν(GeV) Event selection GPS Expected arrival time of ν FC ν 3 ±500µsec HE Trig. Tspill 10 TSK events 10 2
10 Atm ν BG fully contained 22.5kt fiducial volume 1
-500 -250 0 250 500 ∆T (µ∆sec)(T) µs 20 ±5µsec number of events 15 56 observed events +6.2 80.1 -5.4 expected 10 null oscillation prob. 1.3% 5 0.48×1019p.o.t. 0 (1999-2001) -5 01.5µs 5 (1/2 of the proposal) ∆T (µ∆sec)(T) µs Oscillation vs. data 10 CC quasi elastic reaction Eν from (Eμ and θμ) 9
8 Best fit point (sin22θ , ∆m2) Events Normalized by area -3 2 7 = (1.0, 2.8×10 eV )
6 ★KS test prob.(Eν dist): 79%
5 ★NSK(expected by osc.)=54
Number of events Best fit NSK(observed)=56 4
3 No osc.
2
1 Both NSK and Eν- distribution are consistent 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 rec E ν with oscillations. Eν(reconstructed) (GeV) Allowed parameter region based on Eν and NSK -1 -1 νµ - ντ ) ) 2 10 10 K2K2 Super-K (eV 2 (eV 2 m m ∆ ∆
-2 -2 10 10
-3 -3 10 10
68% C.L. % 68 90% C.L. % 90 99% C.L. 99% -4 -4 10 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.2 0.4 0.6 0.8 1 2 sin22θ sin 2θ
K2K and atmospheric neutrino data are consistent. New K2K data after SK reconstruction work in 2002 SK recovery FC 22.5kt 70 1999 2000 2001 2003 events
60 K2K-I 50 +6.2 80.1 -5.4 expected 56 observed 40 obs/exp=0.70±0.09(stat) K2K-I K2K-II K2K-II (until April 2003) 30 +2.3 26.4 -2.1 expected 16 observed 20 K2K-I + II Preliminary obs/exp=0.61±0.15(stat) 10 Event rates are = % KS probability 64.3 consistent between 0 0 102030405060 K2K-I and -II POT vs events CT *1018 POT ν θ ? ν 13 ∆ 2 m 12=0 Reactor exp. → assumed P(θe X ) 2 2 2 1ν.27∆m L =µ ⋅ sin 2 13 sin ( ) ν →ν ν E e X ν → ～ 1km P( e ) θ 2 2 2 2 1.27∆m L = sin ⋅sin 2θ ⋅sin ( ) 23 13 E Atmospheric M ν atter =0.50±0.16 neutrinos effect
Long baseline exp. ν →ν µ e
250km Data all data CHOOZ νe 300 e+ energy µ disappearance450 Sub-GeV e-like Sub-GeV -like 250 400 500 ν signal 200 MC 350 150 400 300 250 100 300 200 50
0 200
Number of Events 150 Number of Events K2K electron 0246810 100 100 MeV appearance 50 SK Atmospheric0 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 neutrinos cosθ cosθ Data 1 µ Multi-GeV e-like 350 Multi-GeV -like + PC BG 2.4 140 300 120 ν BG 2.0 250 µ 100 ν BG 0.35 80 200 e 60 150 (ε=55%) Number of Events 40 Number of Events 100 20 50 No evidence for non-zero θ13 0 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 cosθ cosθ θ Constraints on 13 K.Nishikawa LP03 Lower ∆m2 and K2K global analysis ν hep-ph/0308055 e appearance Old SK atm. data used
SK New SK ν atm. data atm. CHOOZ e used 2 θ disappearance (old =0.5・sin 2 13 analysis) (Similar but slightly weaker constraint from Palo Verde) 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.) Î Very important to check the LSND results.
MiniBooNE νµ event flux (real)
MiniBooNE taking data since Aug.2002. (ν WG H.Tanaka) Status • Known; ∆ 2 θ m 23(13), 23, ∆ 2 θ ∆ 2 m 12, 12 and the sign of m 12
•Unknown; θ 13 (known to be small), δ(CP phase), ∆ 2 sign of m 23(13)
Need experimental confirmation; Oscillation τ appearance
WG discussions
JPARC-nu MINOS (start end 2004)
730km
Far detector constructed, atmospheric neutrino run since summer 2003
MINOS sensitivities
2θ =sin 13 CNGS (start 2006) Primary goal: detection of tau neutrinos OPERA ICARUS 732km
3.0 kton liq. argon detector
Hybrid emulsion Bubble chamber detector (1.7kton) like image
τ Observe decay Detailed kin. T600 data in ν study of τ 2001 Emulsion layers events Expected number of τ events 1.6・10-3 2.5・10-3 4.0・10-3 background (5yrs) OPERA 4.3 10.3 26.3 0.65 ICARUS 4.9 11.9 30.5 0.7 JPARC neutrino project (start 2008 or 9?)
Off-axis beam JPARC
Target Decay Pipe SK θ 295km Horns 2.5±0.5゜ ×100 more intensity than K2K, Eν < 1GeV
-1 90% C.L. sensitivities 10 7 10 θ sensitivity JPARC sensitivity ) 2 13 (eV 2
/yr) OFF-axis 6 (5yrs) m ∆ 2 10 2deg. -2 10 5 10 νµ 10 4 ν e -3 ×20 3 10 10 JHF 5year Max. osc. Eν OAB 2deg. 2 CHOOZ excluded 10 2
Flux (/100MeV/cm for 0.003eV -4 10 -3 -2 -1 10 10 10 1 sin22θµ 0 1 2 3 4 5 2 e Eν (GeV) 0.5・sin 2θ13 2 θ sin 2 23 Status: waiting for decision (approval?) at the end of this year NuMi Off-axis (year ?) Neutrino oscillation experiment with an Off-Axis detector (lower energy neutrinos)
Matter effect: MuNi-Off-axis > JPARC
hep-ph/0301210 6 (a) 25 2 ∆m > 0 25 5 atm ∆m2 < 0 atm 30 4
35 Possible 3 30 , NuMi)[%]
sites e 40 ν 2 35
Æ 50
µ 40 ν 1 50 EJHF = 0.6 GeV P( ENuMINuMI = 1.5 GeV 0 0123450 ν ν P( µÆ e, JPARC)[%]JHF P Detector: 40kton fiducial mass Determine the Low Z, high granularity detector sign of ∆m2 Similar sensitivity as JPARC-ν Importance of understanding of neutrino interactions Example: 2 θ For sin 2 23=1.00 (JPARC) Stat. error: +/- 8.5 QE + non-QE Non-QE BG: 43 Non-QE 20% syst. In non-QE/QE ratio = 8.5 events Non-QE/QE ratio must be understood (much) better than 20%.
) 2 4.5
m
c 8 Muni-Off-axis
3 4
-
0
QE events only 1 3.5
( No osc. s 3
n
o
Oscillation i t 2.5 2 c JPARC (sin 2θ =1.00) e 23 s 2
s
s 1.5
o Inelastic
r
c
1
0.5 CCqe 0 012345 Eν (GeV) WG discussion θ Reactor experiments for 13 (Do better than CHOOZ did)
Good: Relatively cheep(?), θ If measured, the measurement is really a measurement of 13 θ ∆ 2 (No ambiguity from 23, sign of m , CP phase) Challenge: disappearance (% range) Î control systematics <1%, higher stat. 2 (identical) detector system, ～50tons each underground
About 2km
One possible site … Serious discussions in Russia, USA, Europe and Japan Factor 5-10 improvement seems possible Toward the measurement of δ(CP phase) Super-beam experiments Neutrino factories based on µ storage ring Hyper-K (1Mton)
Ability to see maximal CP violation 4MW, 2.2GeV SPL (Superconducting Proton BNL Linac) @CERN
130 km • In the past several years, we have learned a lot about the neutrino masses and mixings. ∆ 2 θ ∆ 2 θ • We know m 23(13), 23, m 12, 12 and the sign of ∆ 2 m 12 . • In the future neutrino oscillation experiments, yet θ δ unknown oscillation parameters ( 13, , and sign of ∆ 2 m 23(13) ) can be measured.