Yury Kudenko

1
Accelerator neutrino experiments new results
and perspectives

• Yury Kudenko
• Institute for Nuclear Research RAS

NPD RAS Session ITEP, 30 November 2007?.
2
Neutrino oscillations ?2? MINOS
OPERA MiniBooNE ?2? NOVA
?? ? ??
?m232, sin22?23
?? ? ??
LSND
sterile ?
?? ? ?e
?13 ?CP(?)
3
Mixing matrix
3 families
solar
atmospheric
link between atmospheric and solar
U parameterization three mixing angles ?12
?13 ?23 CP
violating phase ?
two independent ?m2

4
Mixing and masses
Oscillation parameters
central value 2? interval ?m212
(10-5 eV2) 7.6 7.1 - 8.3
?m231 (10-3eV2) 2.4 2.0 -
2.8 sin2?12 0.32
0.26 - 0.40 sin2?23
0.50 0.34 -
0.67 sin2?13 0.0
lt0.05
Global data from solar, atmospheric, reactor, L
BL accelerator experiments
3 families
Mixing Quarks Leptons 1-2 ?12
13o 33o 2-3
?23 2.3o
45o 1-3 ?13 ? 0.5o lt10o

?CP ?
5
Mass spectrum
Inverted
Normal
6
Long baseline accelerator experiments
Main goals search for ?? ? ?e
?13 precise measurement
?m223 ?23 mass hierarchy
?m213 gt 0 or ?m213 lt 0 ?CP
?CP ? ?13 Ue3 sin
?13exp(-i?CP)
LBL experiments cannot distinguish between Dirac
and Majorana neutrinos do not provide
information about absolute ? mass
7
Oscillation experiments Appearance and
Disappearance
8
First LBL experiment ?2?
?? disappearance
1999-2005
?? ? ?? (?? ? ?x)
?m2 ? 2?10-3ev2
L/E? ? 200 L250 km ltE?gt ? 1.3 GeV
?? 98.2 ?e 1.3
Predictions of ? flux and interactions at Far
Detector by Far/Near ratio
Signal of ? oscillation at K2K Reduction of ??
events Distortion of ?? energy spectrum
1 event/2 days at SK
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K2K final result
PRD74072003,2006

- Events
- Shape distortion
Expected 158.1 9.2 8.6 Observed 112
Expected shape (no oscillation)
Best fit
Null oscillation probability events 0.06
(3.4?) shape 0.42 (2.9?)
Null oscillation probability (shape events)
0.0015 (4.3?)
Kolmogorov-Smirnov test Best fit probability
37
Best fit values sin22? 1.00 ?m2 eV2 (2.80 ?
0.36)?10-3
10
MINOS
Precise study of atmospheric neutrino
oscillations, using the NUMI beam and two
detectors
Beam NuMI beam, 120 GeV Protons ? ??- beam
Detectors ND, FD Far Det 5.4 kton magnetized
Fe/Sci Tracker/Calorimeter at Soudan, MN (L735
km) Near Det 980 ton version of FD, at FNAL (L
? 1 km)
11
First MINOS result
PRL 97(2006)191801
1.27x1020 POT ? expect 336 ? 14.4
detect 215
k2k
Best fit values sin22? 1.00 ?m2 eV2 (2.74
0.44 - 0.26) ? 10-3
12
New MINOS result
J.Thomas, talk at Lepton-Photon2007
2.50 POT analyzed 2x statistics of 2006 result
Improved analysis
expected (no osc.) 738?30 observed
563
Comparison of new and old MINOS results
?m223 (2.38 0.20 -0.16) x 10-3 sin22?231.00
-0.08
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?m223 and ?23 SK/K2K/MINOS
?m223? ?m213 (2.4 ? 0.2)x10-3 eV2 ?23
45o
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MINOS projected sensitivity
M.Ishitsuka, talk at NNN07
After 5 years running expected accuracy of ?m232
and sin22?23 ?10
chance for first indication of non-zero ?13
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OPERA
?? ? ?? direct search
P(?? ? ??) cos4?13sin2?23sin21.27?m223L(km)/E(G
eV)
kink
Target mass 1300t
E/L 2.3?10-2 ? 10?m223 (atm)
?
?
pure beam 2 anti ?? lt1 ?e
?
after 5 years data taking 22000 ?
interactions 120 ?? interactions 12 ??
reconstructed lt1 background event
?
??
16
OPERA Detector
Muon spectrometers
?p/p lt 20 for plt50 GeV
n beam
Two supermodules

• Hybrid Detector
• Two supermodules Target Mass 1766 tons
• 2 Magnetic spectrometers with RPC Drift tubes
• 2 x 31 Target Tracker planes and Target Walls
• 206,336 ECC bricks (56 Pb/Emulsion layers)
• 12 M Emulsion plates (thin double-coated)

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OPERA ?? ? ?? sensitivity
M.Spinetti, talk at NNN07
full mixing, 5 years run 4.5 x1019pot/y
New MINOS
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?13 global
T. Schwetz, hep/ph 0606060
?13 ? 100
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LSND result
?m2 0.2 10 eV2 best fit ?m2 0.210
eV2 sin22? 0.003
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Oscillations before first MiniBooNe result
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MiniBooNE
FNAL 8 GeV Beamline
50 m decay pipe
12m sphere filled withmineral oil and 1520
PMTslocated 500m from source
decay region ? ? ??? ,  K ? ???
little muon counters
measure K flux in-situ
magnetic horn meson focusing
MiniBooNE detector
Protons from the 8 GeV booster ? Neutrino Beam
ltE?gt 1 GeV
?? ??e?
movable absorber stops muons, undecayed mesons
????e ???
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MiniBooNE result
6 x1020 POT
PRL 98231801,2007 arXiv0704.1500
No ?e excess in oscillation signal region E?gt
475 MeV
however
23
MiniBooNE result
No evidence for ?? ? ?e appearance oscillations

• ?? ? ?e (LSND anti-nu)
• excess at low energy

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Possible interpretations
if low-energy excess is confirmed to be a
real signal

• Non-oscillation

? N ? ? N ? N ?
Coupling between ?, Z and ?
? ? 2.6?10-41(E?/GeV)6(g?/10)4 cm2
?.?.????????, ?.?.?????????, ?.?.??????, ?? 33
(1981) 1597 J.Harvey, C.Hill, R.Hill,
arXiv0708.1281hep-ph

• Oscillation

3 1 model ruled out M.Maltoni, T.Schwetz,
arXiv0051.0107hep-ph
3 2 or 3 3 models
M.Maltoni, T.Schwetz, arXiv0051.0107hep-ph
A.Nelson, J.Walsh, arXiv0711.1363hep-ph
Extra dimensions H.Pas, S.Pakvasa, T.Weiler,
hep-ph/0504096 (prediced low-energy excess)
Lorentz violation T.Katori, A.Kostelecky,
R.Tayloe, hep-ph/0606154
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Second generation LBL experiments
Off Axis Neutrino Beams

• Increases flux on oscillation maximum
• Reduces high-energy tail and NC backgrounds
• Reduces ?e contamination from K and ? decay

T2K NOVA
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T2K (Tokai to Kamioka)
JPARC facility
1GeV ?? beam (?100 of K2K)
on-axis
off-axis
? beam
JPARC MINOS
Opera K2K E(GeV) 50
120 400 12 Int(1012 ppp)
330 40 24
6 Rate (Hz) 0.29 0.53
0.17 0.45 Power (MW) 0.77
0.41 0.5 0.0052
Statistics at SK OAB 2.5 deg, 1 yr 1021 POT,
22.5 kt 2200 ?? tot 1600 ?? charged current
?e lt 0.5 at ?? peak
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T2K off-axis beam
0o

OA2
OA2.5
OA3
0 deg
28
T2K setup
Possible Future ? T2K-II
ND280m
ND2km
SK
? monitor
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Principle Goals of T2K
- Search for ?e appearance ?13 sensitivity ?
1o (90 c.l.)
Background uncertainty 10 ?CP 0 ?CP
?/2 ?CP - ?/2 ?CP ?
?m22.5x10-3

• Measurement ?m223
• with accuracy of 1
• ?(sin22?23) ? 0.01
• ?(?m223) lt 1?10-4 eV2
• 
  
  
  

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T2K sensitivity to ?13
CHOOZ limit
ambiguities ?CP - ?13 sign ?m223
?23
31
NO?A
810 km baseline
Far Detector
15 ktons 15.4m x 15.4m x 70m 1003 liquid
scintillator planes (80 active) Scintillator
cells 3.8 x 6.0 x 1540 cm3 Read out from one
side per plane with APDs
Near detector
Active element Liquid scintillator U-shaped WLS
fiber
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NO?A
P(?? ? ?e) depends on sin22?13 sign ?m223
?CP
matter effects increase (decrease) oscillations
for normal (inverted) hierarchy for ?
Mass hierarchy can be resolved if ?13 near to
present limit using both ? anti-? beams
and sin22?13 from T2K reactor experiments
33
?13 sensitivities vs time
A.Blondel et al., hep-ph/0606111
Daya Bay goal
Short baseline reactor experiments Double-Chooz
and Daya Bay ?13 ( insensitive to ?CP)
34
Conclusion
K2K confirmation of atmospheric
neutrino oscillations
discovered by SK MINOS confirmed the
SK ? K2K results high
precision measurements of oscillation
parameters MiniBooNe rules out (98 cl) the
LSND result as ?? ? ?e
oscilations with ?m2 1 eV2
new anomaly appears
run with anti-? beam
OPERA data taking begun in 2007 T2K-I
neutrino beam in 2009

Main goal for next 5 years ?13