Recent Results from Neutrino Experiments and Plans for the Neutrino Super Beam in Japan

1
Recent Results from Neutrino Experiments and
Plans for the Neutrino Super Beam in Japan
Y.Totsuka, KEK NSS-2003, 031021

• Discovery of neutrino oscillations ? finite
  neutrino masses (n2 and n3) (1998 present)
• Small as expected
• Mixing among neutrino flavors expected
• Quark mixing implies small mixing

2
Mixing matrix
Interacting states
Free moving states (mass eigenstates)
(
)
(
)
(
)
ne nm nt
n1 n2 n3
Ue1 Um1 Ut1
Ue2 Um2 Ut2
Ue3 Um3 Ut3

U (Maki-Nakagawa-Sakata Matrix)
)
(
sijsinqij, cijcosqij, dCP

• Discovery of large mixing angles, q23 and q12

3
Atmospheric neutrinos - I
Super-K
e
ne
Earth

• Expected event rate is uncertain by 15
• nm ne 2 1 (low energy) known better than 5
• Up-down symmetry for En gt 1 GeV

4
Super-Kamiokande (1996)

• 1996-
• 50000ton water
• 11146 50cmf PMT (40 photo coverage)
• 1000m underground
• Min det. energy 5 MeV
• Basic reactions
• nm N ? m X
• ne N ? e X

5
Super-Kamiokande II

• Accident on Nov 12, 2001
• Repaired and restarted in Dec, 2002
• Inner detector with 5200 20 PMTs
• Outer detector with 1885 8 PMTs

SK-II Cosmic ray muon sample
6
1489 day FCPC data 1646 day upward going
muon data
c2170.8/170 d.o.f. at (sin22q23, Dm232)(1.00,
2.0x10-3eV2) c2445.2/172 d.o.f. (null
oscillation)
7
Allowed region of the oscillation parameters
(complete SK-I dataset)

• Assuming nm ? nt oscillation
• Best fit
• c2min 170.8/170 d.o.f
• at (sin22q23, Dm232) (1.0, 2.0 x 10-3 eV2)
• 90 CL allowed region
• sin22q23 gt 0.9
• 1.3x10-3 lt Dm232 lt3.0x10-3 (eV2)
• Assuming null oscillation
• c2 445.2/172 d.o.f

Soudan-2
MACRO
Super-K 68 CL 90 CL 99 CL
8
K2K
Long baseline neutrino oscillation experiment

• 12 GeV PS at KEK
• Neutrino beamline
• ltEngt 1.3GeV
• 98 purity
• Beam monitors and near detector
• beam direction
• p measurement
• nm flux and spectrum
• Far detector
• nm flux and spectrum

250km
9
Best fit 1Rm spectrum Nsk
Total number of obs. Events 56 16
(Jan03-Apr03) Expected w/o oscillation
80.6 7.3-8.0 24 2.3-2.1

• Best fit point (sin22q23 , Dm232) (1.0,
  2.8x10-3eV2)
• KS test prob.(shape) 79
• NSK54 (Obs.56)
• Very good agreement in shape NSK with
  atmospheric neutrinos

Expected w/o oscillation Normalized w/o
oscillation Normalized with best fit oscillation
10
Comparison with SK atm n observation
90CL
SK (FCPCupm)
K2K(1Rm shapeNSK)
11
Solar image
12
SNO ne ? ne (ES) ned ? epp (CC) nd ? npn,
Cl(n,g)Cl, (NC)
INCOs Creighnton mine Sudbury, ON, Canada
Control room
Electronics hut
9456 of 8 inch PMTs
2km
(6010mwe)
SNO

• photo coverage 55 (Rlt7m)
• cosmic ray muons 70 events/day
• fiducial volume 0.7kt (R,5.5m)
• Trigger rate (data) 68Hz
  (2MeV threshold)
• Trigger efficiency 100_at_3MeV
• From compton e- from 16N source (5 MeV)
• vertex resolution 16cm
• energy resolution 16
• angular resolution 27?
• NaCl in D2O

1000 ton heavy water (12mf acrylic vessel)
17005300 ton light water (17.8mf stainless steel
support, 34mh x 22mf barrel-shaped cavity)
13
Super-K SNO combined (as of 2002)
SNO ?CC 1.7-0.05-0.09 ?ES
2.39 -0.12 ?NC 5.09 SK
?ES 2.32-0.03 Evidence for an active
non-ne component!
?CC ?e ?ES ?e 0.154 ??,? ?NC ?e ??,?
x106/cm2/s
0.24 - 0.23
0.44 0.46 - 0.43 - 0.43
0.08 - 0.07
14
SNO rates and day/night spectra
and Super-K zenith spectra
ne ? nm oscillation
-3
-4
-5
-6
log Dm2 (eV2)
-7
-8
-9
-10
-11
-4
-3
-2
-1
0
1
Log tan2q
15
Kam-LAND

• 1000m3 liquid scintillator
• 3000m3 oilwater shield
• 1300 17-inch PMTs 600 20-inch PMTs
• Anti-ne from reactors (L170km)
• Detect e from ne p ? e n (Eth 1.8 MeV)
• Observation started on 22 Jan 2002

16
Kam-LAND result

• 145.1 live days, 162 ton year exposure
• Te gt 2.6 MeV, 86.8-5.6 ev expected
• 56 ev observed with 1 BG estimated

• Te gt 0.9MeV
• 124.8-7.5 ev expected
• 86 ev observed with 2.9 -1.1BG estimated

17
KamLAND confirms the LMA solution!
18
SNO
FIG. 5 Global neutrino oscillation contours.
(a) Solar global D2O day and night spectra,
salt CC, NC, ES fluxes, SK, Cl, Ga. The best-fit
point is Dm2 6.5 10-5, tan2q 0.40, fB
1.04, with 2/d.o.f.70.2/81. (b) Solar global
KamLAND. The best-fit point is Dm2 7.1 10-5,
tan2q 0.41, fB 1.02. In both (a) and (b) the
8B flux is free and the hep flux is fixed. fB
8B flux measured / SSM.
Nucl-ex/0309004v1 6Sep2003
19
What to do next

• Measure
• q31 and Dm312 ( Dm232)
• d
• Dm122, Dm232, q12, q23 precisely

Quarks sin22q12 0.188 -0.007 sin22q23
0.0064-0.0010
20
nm ? ne , electron appearance
P(nµ? ne ) 4c132s132s232 sin2(Dm312L/4En)(1
2a(1-2s132)/Dm312)
8c132s12s13s23(c12c23 cosd s12s13s23)
cos(Dm232L/4En ) sin(Dm312L/4En)
sin(Dm212L/4En) -
8c132c12c23s12s13s23 sind
sin(Dm232L/4En ) sin(Dm312L/4En)
sin(Dm212L/4En)
4s122c132(c122c232 s122s232s132
- 2c12c23s12s23s13 cosd) sin2(Dm212L/4En)
-8c132s132s232(1
2s132)(aL/4En)
cos(Dm232L/4En ) sin(Dm312L/4En) , where a eV2
2v2GFneEn 7.610-5 r g/cm3 En GeV ,
red terms change sign for anti-neutrinos
21
Strategy and Sensitivity Goal (Phase I)

• 5 years
• Precisely measure q23 and Dm232.
• ne appearance search
• Sensitivity goals
• dsin22q23 0.01
• dDm232 lt 1x10-4 eV2
• sin22q13 0.006 (90 CL)
• Study neutrino interactions at the near detector

22
T2K (Tokai-to-Kamioka)
J-PARC
Hyper-Kamiokande
23
J-PARC
(180 MeV,

• Joint Project by KEK and JAERI
• 3 GeV RCS spallation-neutron and muon sources
• Life and material sciences
• 50 GeV MR slow and fast extracted protons
• Kaon physics
• Neutrino physics (long baseline oscillations)
• LINAC intense proton source
• ADS

24
(No Transcript)
25
3 GeV RCS

• injection energy 400 MeV(180 MeV)
• extraction energy 3 GeV
• harmonic number 2
• repetition rate 25 Hz
• of protons / pulse 0.83 E14
• average beam current 333µA
• beam power 1 MW

Magnetic alloy cavity
26
50 GeV MR

• Beam energy 50 GeV (40 at phase 1)
• 1 cycle 3.53s
• 8 bunches in 9RF buckets
• Bunch spacing 598ns
• Spill width 5ms
• Bunch length 36ns (3s)
  6ns (1s)
• of protons 3.31014 ppp
• Beam current 15mA (slow extraction)
• Rf frequency 1.68 (inj.) 1.73 (ext.)
  MHz
• nm flux at SK 1.9107 / cm2yr(1yr 1021
  pot 123 days at .75MW)

3.53s
slow
1.9s
1.96
0.7
fast
0.7
0.17
Injection 0.17s acceleration
1.96s extraction 0.7 s current down
0.7 s total 3.53s
2.5Off Axis, 130m decay pipe
27
Neutrino beam line
N
JAERI_at_Tokai-mura (60km N.E. of KEK)
50GeV PS
Construction 20012007
3GeV PS
600MeV Linac
(Approval in Dec.2000)
Near Detector (280m)
Neutrino Beam Line
To Super-Kamiokande (295km away)
28
Off Axis Beam

• WBB with a misaligned beam line from the det.
  axis
• High intensity at low energy 4500 int./22.5kt/yr
• Contamination ne 0.8(0.2 _at_ peak)

Decay Kinematics
En (GeV)
0 0.4 0.8 1.2
1.6 2
Ep (GeV)
En (GeV)
2x10-3eV2, L 295km
29
Fast extraction section
neutrino beamline
30
Arc Section
combined function SC magnets
31
Focusing Section
Target station
solid graphite, 30mm in diam, 900mm long
32
Horn system
Carbon target

• I300kA, three short horns
• Need to tolerate big heat load from radiation
• Stress analysis is in progress

33
Decay Volume
Top view
130m from target
Side View
To Super-K
1.3deg
3.5deg
50o
4MW beam can be accepted.
(Temperature is controllable under 100o by
intermittent operation)
max.120o (half year continuous operation)
14o
Water cooling pipe
34
Near detector at 2km from the target
Total mass 1077ton
n beam
9.2m
4m
Fid. Mass 100ton
8m
16.2m
Near detector should look like
Far detector looks like
35
Far/near ratio (OA 2deg)
spectrum
36
(No Transcript)
37
Strategy and Sensitivity Goal (Phase II)

• Intensity upgrade to 4 MW
• 1 Mton far detector, Hyper-Kamiokande
• Search for CP violation

38
Hyper-Kamiokande (1Mt water)

• Precision neutrino oscillation study
• Proton decay search

• RD (complete in 2 years)
• Cavity excavation and its stability
• New light detector Hybrid Photo-Detector, HPD
  (50cmf)

39
Sensitivity (3s) to CPV (T2K Phase II)
40
Conclusions

• Rapid progress in measuring masses and mixing of
  neutrinos
• Dm232 1.3 - 3.010-3 eV2, sin22q23 0.9 1.0
• Dm122 6 - 910-5 eV2, sin22q12 0.7
  0.9
• Their precisions need to be improved
• q23 and d are still unknown
• J-PARC can produce nm beam 100 times stronger
  than K2K (proton beam power 0.75 MW)
• Sensitivities sin22q31 gt 0.006 (90CL)
• If q31 measured, a further upgrade will be
  considered
• proton beam power 4 MW
• 1 Mton Hyper-K
• A lot of uncertainties in future
• Linear collider, budget deficit, etc

41
Supplement
42
JSNS23 neutron beam lines