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