takaaki kajita, icrr, univ. of tokyo now2004, sep 2004
TRANSCRIPT
Takaaki Kajita, ICRR, Univ. of Tokyo
NOW2004, Sep 2004
Outline
• SK Atmospheric neutrino results
, L/E, and 3 flavor analysis
• K2K
from K2K-I and -II
• T2K (Future long baseline experiment) • Summary
Only 2 and 3 flavor neutrino oscillations
SK collaboration: Japan, USA, Korea, Poland
Event classification and statisticsFully Contained (FC) (E ~1GeV) (12180)
Partially Contained (PC) (E ~10GeV) (911)
Through-going (E~100GeV) (1842)
Stopping (E~10GeV) (418)
Red: observed number of events in SK-1
(total number = 15351)
Recent improvements• New flux based on the 3 dimensional calculation
• Tuned neutrino interaction MC based on the K2K data
• 15 37 systematic error terms (S.Moriyama’s talk)
3D
1D
(deg)
Super-K atmospheric neutrino data
1489day FC+PC data + 1646day upward going mu
on data
CC e CC
Binning for 2 flavor oscillation analysis
E
Single-Ring
Multi-Ring
Up-stop
Up-through
18 momentum bins x 10 zenith bins = 180 bins in total
Single-Ring e
PC
Each box has 10 zenith bins
Multi-GeV
Sub-GeV
CC e CC
38
1
exp
237
1
180
12
2exp2
1)(,)(
Jj
i
j
o
iij j
j
i i
i
obs
i fPNNNN
Neutrino oscillation parameters
90%C.L.
92.02sin
)(104.35.1
23
2
23223
eVm
2=175.3/177dof @ m2=2.1x10-3,sin22=1.00
(full paper will be published soon)
oscillation
decoherence
decay
Further evidence for oscillations Strong constraint on oscillation parameters, especially m2
-like multi-GeV + PC
Should observe this dip!
SK collab. hep-ex/0404034
Selection criteria
Following events are not used:
★horizontally going events
★low energy events
Select events with high L/E resolution
((L/E) < 70%)
FC single-ring -like
Full oscillation 1/2
oscillation
(L/E)=70%
Similar cut for: FC multi-ring -like,
OD stopping PC, and
OD through-going PC
2121 FC -like and
605 PC
L/E distribution
MC (no osc.)
1489 days FC+PC
Evidence for oscillatory signature
Mostly down-going
Mostly up-going Osc.
Decay
Decoh.
Decay and decoherence disfavored at 3.4 and 3.8 levels, respectively.
Allowed neutrino oscillation parameters
2min=37.9/40 d.o.f
@ m2=2.4x10-3,sin22=1.00(sin22=1.02, 2
min=37.8/40 d.o.f)
1.9x10-3 < m232 < 3.0x10-3 eV2
0.90 < sin2223 (90% C.L.)
Stronger constraint on m2
Consistent with that of the standard zenith angle analysis
Search for non-zero 13
Electron appearance in the 5 – 10GeV(E) upward going events.
E
LmP e
2232
13
2
23
2 27.1sinsinsin)(
s213=0.05 s213=0.00 null oscillation
MC, SK 20yrs
Electron appearance
1+multi-ring, e-like, 2.5 - 5 GeV
cosE(GeV)
cos
)( eP
Matter effect
(m122=0 assumed)
Super-K e-like data
Multi-GeV, single-ring e-like Multi-GeV, multi-ring e-like(special)
No evidence for excess of upward-going e-like events
Binning for 3flavor analysis
E
Single-Ring
Multi-Ring
Up-stop
Up-through
37 momentum bins x 10 zenith bins = 370 bins in total
Multi-Ring e
Single-Ring e
PC-stop
PC-through
Same as 2 flavor analysisDifferent binning from 2 flavorSpecial in the 3 flavor ana.
Fewer number of events per bin
Poisson statistics to claculate 2
Multi-GeV
Sub-GeV
CC e CC
3 flavor analysis from Super-K
Normal3
21
prelim.
sin213sin223
sin
2 1
3
m2
3 flavor analysis from Super-K
Inverted
3
21
prelim.
sin213
m2
sin223
sin
2 1
3
No evidence for non-zero 13
(No information on the mass hierarchy)
Studies in progress….• Search for tau neutrino interacti
ons
• Oscillation analysis with the solar terms
Simulated interaction
Event rate = 1/kton/year
Only upward going
Statistical estimate of the interactions
P.Lipari NOON2004
10
1
sub-GeV e-like events Peres, Smirnov NPB 680 (2004) 479
Also, M.Maltoni, this meeting,hep-ph/0408170
SK-II atmospheric neutrino data
DATAMC (no oscillation, normalized by live time)
Live timeFC + PC 311.5 days
Upward going 243.5 days
MC (oscillation, m2=2.1×10-3eV2, normalized by live time)
SK-II event
Preliminary!
K2K CollaborationK2K Collaboration
250km250km
JAPAN, KOREA, U.S.A., POLAND, CANADA, ITALY, FRANCE, SPAIN, SWITZERLAND, RUSSIA
More details: K.Kaneyuki’s talk
K2K Analysis Overview
Near detectors #, p and
(E)nearKEK
Observation# and E
rec.
Expectation# and E
rec.
(sin22, m2)
SK
Far/Near Ratio
(E)far
int. MC
int. MC1.0 2.0
Far/Near Ratio
E(GeV)
beam MC w/PION Monitor
12GeV PS(8.9×1019 POT for Analysis)
Near detectors• 1KT Water Cherenkov Detector (1KT)• Scintillating-fiber/Water sandwich Detector (SciFi)• Scintillator Bar Detector (SciBar) after 2003• Muon Range Detector (MRD)
Muon range detector
Front detector measurements: momentum and angular distributions
(deg.)0 90
p (MeV/c)0 1600800
1kton water Cherenkov
1kton water Cherenkov
Also, measurements by SciFi, SciBar and MRD detectors.
Prediction of the number of events(150.9 +11.6-10.0) and
spectrum at SK.
QE
1
NC
DisCoh
Event selection in Super-Kamiokande
TSKTspill
GPS
SKTOF=0.83msec
108 events obs’d
Decay electron cut
Evis > 20MeV
No activity in outer detectorEvent vertex in fiducial volumeEvis > 30MeV
Analysis time window
500sec
5sec
TDIFF. (s)
150.9 events exp’d
Summary of K2K-SK events
K2K DATA MC
FC 22.5kt 108 150.9 +11.6 -10.0
1ring 66 93.7
-like 57 84.8
e-like 9 8.8
Multi Ring 42 57.2
preliminaryK2K I+II
K2K energy spectrum (based on single-ring -like events)
MC normalization: number of events
Erec[GeV]
Nu
mb
er
of e
vent
s
Deficit of events
MC (no osc.)
MC (osc.)
preliminary
• Best fit values.
sin221.53
m2 = 2.1210-3 eV2
• Best fit values in the physical region.
sin221.00
m2 = 2.7310-3 eV2
logL=0.64
Best fit oscillation parameters
sin22=1.53 can occurr due to a a statistical fluctuation with 14.4% probability.
Toy MC
sin22
m2
1.00
2.73
14.4%
preliminary
1.53
Allowed parameter regionm
2[e
V2]
sin22
preliminary
Best fit values (in the physical region)
sin22= 1.00m2 [eV2] = 2.710-3
m2=(1.7~3.5)×10-3 eV2
(90% C.L.) @ sin22=1.0
K2K
SK(zenith)
SK (L/E)
90%CL
K2K
Super-Kamiokande
250km J-PARC
JAERI
Collaboration (at present): Canada, China, France, Italy, Japan, Korea, Poland, Russia, Spain, Switzerland, UK, USA
T2K
T2K main physics goals
• Discovery of non-zero 13
• Precise measurement of sin2223 and m232
(Discovery of non maximal 23?)
• Discovery of non-zero CP phase
1st phase
2nd phase
If 13≠0 observed
J-PARC Facility
Nuclear and ParticleExperimental FacilityMaterials and Life Science
Experimental Facility
Neutrino to Kamiokande
Linac(350m)
3 GeV Synchrotron(25 Hz, 1MW)
Nuclear Transmutation
50 GeV Synchrotron(0.75 MW)
J-PARC = Japan Proton Accelerator Research Complex
Under construction, expected completion (Phase-I)= end 2007
LINAC
3GeV
50GeV dipole magnets 50GeV
T2K neutrino facility
Near detectors (280m,and 2km(not approved yet)
To SK
T2K K2K
E(GeV) 50 (40 @t=0)
12
Int.(1012ppp) 330 6
Rate(Hz) 0.275 0.45
Power(MW) 0.75 0.0052
OA3°
OA0°OA2°
OA2.5°
Off axis beam facility
Measurement of m2 and sin2223
Data sample: SK Monte Carlo, Fully-contained single-ring, muon-like events.
Event
fract
ion
Typical JHF neutrino energy
Important to run the experiment with low energy beam.
π
π
E from E and
~ OA 2.5 deg. ~
Reconstructed neutrino energy distribution
No oscillation
reconstructed E (GeV)
non-QE
m2= 2.5 x10-3 eV2
Quasi Elastic
reconstructed E (GeV)
Precise measurement of 23 , m223
Assumed systematic errors
normalizationnon-qe/qe ratioE scaleSpectrum shapeSpectrum width
( 5%)( 5%)( 1%)(20%) ( 5%)
(m223)
<1×10-4 eV2
(sin2223)~0.01
True m232 (10-3eV2)True m23
2 (10-3eV2)
13Present status:
BG (NC 0 ….)
Signal for non-zero 13 (e)
sin213
E
Lm
P e
2232
13
2
23
2 27.1sinsinsin
)(
Allowed
Measurement of e
sin2213 (CC+NC) Beam e Osc’d e Signal+BG
0.1 12 16 122 150
0.01 12 16 12.2 40
Expected signal for
CH
OO
Z lim
it0 1 2 3 4 5
reconstructed E(GeV)
exp’d signal+BGtotal BG BG
Num
ber
of e
vent
s
50
0
10-3 10-2 10-1 1
10-1
10-2
10-3
10-4
m2
(eV
2 )
sin2213
BG=10%
Updated
More details: K.Kaneyuki’s talk
T2K Phase-II
★0.77 → 4 MW beam power
★ ~ 1 Mton detector (Hyper-Kamiokande) CP
Violation
106 events (both and anti-)
Assumptions
252
1212
232
2323
109.6,34
108.2,45
eVm
eVm
Solid line: w/ matterDashed line: w/o matter
(not updated to the most recent
solar parameters)
01.02sin 13
2
sin2213=0.1m31<0
m31>0
90%C.L. stat only90%C.L. stat+2% syst.
3 stat only
3 stat+2% syst.
# of e- events including BG
# of
e+ e
vent
s in
clud
ing
BG
CP phase
Expected CP violation signal (example)Neutrino run=2years, anti-neutrino run=6.8years, 4MW, 0.54Mton fid. Vol.
3 CP sensitivity
no BGsignal stat only
(signal+BG) stat only
stat+2%syst.
stat+5%syst.
stat+10%syst.
CHOOZ excludedsin2213<0.12@m31
2~3x10-3eV2
JHF-I: No indication for sin22θ13
3 CP sensitivity : ||>20o for sin2213>0.01 with 2% syst.
sin2 2
13
sin
Beam Transfer line from 3GeV toMaterial and Life science Facility)
Decay Volume ~110m
OA2o
OA3o
Target Station ~15m Dump
~10m
Neutrino facility construction
Construction started
Expected completion: early 2009
• Present atmospheric neutrino data from SK are nicely explained by oscillations with;
m2=1.9 – 3.0 × 10-3 eV2
sin22 > 0.90 (SK L/E analysis)• Recent L/E analysis has shown evidence for “oscillatory”
signature.• No sub-dominant oscillation seen yet.• K2K has confirmed neutrino oscillations using the acceler
ator beam.• Neutrino oscillation results from K2K are in good agreem
ent with the SK results.• T2K, a precision neutrino oscillation experiment, will start
in 2009. • If non-zero 13 is observed in T2K phase-I, we would like t
o proceed to T2K phase-II to measure the CP phase.
End