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NOW2004, Sep 2004. SK Atmospheric Neutrino results and LBL experiments in Japan. Takaaki Kajita, ICRR, Univ. of Tokyo. Outline. SK Atmospheric neutrino results n m n t , L/E, and 3 flavor analysis K2K n m n t from K2K-I and -II T2K (Future long baseline experiment)

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Takaaki kajita icrr univ of tokyo

NOW2004, Sep 2004

SK Atmospheric Neutrino results

and LBL experiments in Japan

Takaaki Kajita, ICRR, Univ. of Tokyo


Outline
Outline

  • SK Atmospheric neutrino results

    nmnt, L/E, and 3 flavor analysis

  • K2K

    nmnt from K2K-I and -II

  • T2K(Future long baseline experiment)

  • Summary

Only 2 and 3 flavor neutrino oscillations


SK Atmospheric Neutrino results

SK collaboration: Japan, USA, Korea, Poland


Event classification and statistics
Event classification and statistics

Fully Contained (FC) (E ~1GeV)(12180)

Partially Contained (PC)(E ~10GeV)(911)

Stopping  (E~10GeV)(418)

Red: observed number of events in SK-1

(total number = 15351)

Through-going (E~100GeV)(1842)


Recent improvements
Recent improvements

1D

  • New n 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

qnm(deg)


Super k atmospheric neutrino data
Super-K atmospheric neutrino data

CC ne

CC nm

1489day FC+PC data + 1646day upward going muon data


Binning for 2 flavor oscillation analysis
Binning for 2 flavor oscillation analysis

Each box has 10 zenith bins

Sub-GeV

Multi-GeV

Single-Ring m

Multi-Ring m

Up-stop

Single-Ring e

PC

Up-through

CC ne

CC nm

En

18 momentum bins x 10 zenith bins = 180 bins in total


Neutrino oscillation parameters
Neutrino oscillation parameters

nm nt

90%C.L.

c2=175.3/177dof

@ Dm2=2.1x10-3,sin22q=1.00

(full paper will be published soon)


m-like multi-GeV + PC

SK collab. hep-ex/0404034

L/E analysis

oscillation

decoherence

decay

Should observe this dip!

  • Further evidence for oscillations

  • Strong constraint on oscillation

    parameters, especially Dm2


Selection criteria

FC single-ring m-like

Full oscillation

1/2 oscillation

D(L/E)=70%

Selection criteria

Select events with high L/E resolution

(D(L/E) < 70%)

Following events are not used:

★horizontally going events

★low energy events

2121 FC m-like and

605 PC

Similar cut for: FC multi-ring m-like,

OD stopping PC, and

OD through-going PC


L e distribution

1489 days FC+PC

L/E distribution

MC (no osc.)

Decoh.

Decay

Mostly down-going

Mostly up-going

Osc.

  • Evidence for oscillatory signature

Decay and decoherence disfavored at 3.4 and 3.8s levels, respectively.


Allowed neutrino oscillation parameters
Allowed neutrino oscillation parameters

1.9x10-3 < Dm232 < 3.0x10-3 eV2

0.90 < sin22q23(90% C.L.)

c2min=37.9/40 d.o.f

@ Dm2=2.4x10-3,sin22q=1.00

(sin22q=1.02, c2min=37.8/40 d.o.f)

 Stronger constraint on Dm2

 Consistent with that of the standard zenith angle analysis


Search for non zero q 13

Matter effect

cosQ

En(GeV)

Search for non-zero q13

(Dm122=0 assumed)

MC, SK 20yrs

1+multi-ring, e-like, 2.5 - 5 GeV

Electron appearance

s213=0.05

s213=0.00

null oscillation

cosQ

Electron appearance in the 5 – 10GeV(En) upward going events.


Super k e like data
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
Binning for 3flavor analysis

Same as 2 flavor analysis

Different binning from 2 flavor

Special in the 3 flavor ana.

Sub-GeV

Multi-GeV

Up-stop

Single-Ring m

Multi-Ring m

PC-

stop

Single-Ring e

Multi-Ring e

PC-

through

Up-through

En

CC ne

CC nm

37 momentum bins x 10 zenith bins = 370 bins in total

Fewer number of events per bin

Poisson statistics to claculate c2


3 flavor analysis from super k

prelim.

n3

n2

n1

3 flavor analysis from Super-K

sin2q13

Normal

Dm2

sin2q23

sin2q13


3 flavor analysis from super k1

prelim.

n2

n1

n3

3 flavor analysis from Super-K

sin2q13

Inverted

Dm2

sin2q13

sin2q23

No evidence for non-zero q13

(No information on the mass hierarchy)


Studies in progress

10

1

P.Lipari NOON2004

Studies in progress….

Event rate = 1/kton/year

Only upward going

  • Search for tau neutrino interactions

  • Oscillation analysis with the solar terms

Statistical estimate of the nt interactions

Simulated ntinteraction

sub-GeV e-like events

Peres, Smirnov NPB 680 (2004) 479

Also, M.Maltoni, this meeting,

hep-ph/0408170


SK-II atmospheric neutrino data

Preliminary!

SK-II event

DATA

Live time

MC (no oscillation, normalized by live time)

FC + PC 311.5 days

Upward going m 243.5 days

MC (oscillation, Dm2=2.1×10-3eV2, normalized by live time)


K2k collaboration

250km

n

K2K Collaboration

K2K experiment

JAPAN,KOREA, U.S.A., POLAND, CANADA, ITALY, FRANCE, SPAIN, SWITZERLAND, RUSSIA

More details: K.Kaneyuki’s talk


K2k analysis overview

Far/Near Ratio

beam MC w/

PION Monitor

En (GeV)

1.0

2.0

K2K Analysis Overview

KEK

Near detectors

#n, pm and qm

F(En)near

n int. MC

12GeV PS

(8.9×1019 POT for Analysis)

Far/Near Ratio

F(En)far

n int. MC

SK

Observation

#n and En rec.

Expectation

#n and En rec.

(sin22q, Dm2)


Near detectors
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 m momentum and angular distributions

1600

800

0

pm (MeV/c)

Front detector measurements:m momentum and angular distributions

NC

Dis

Coh p

1kton water Cherenkov

1kton water Cherenkov

1p

QE

0

90

qm (deg.)

Also, measurements by SciFi, SciBar and MRD detectors.

Prediction of the number of events(150.9 +11.6-10.0) and spectrum at SK.


Event selection in super kamiokande

GPS

SK

Tspill

TSK

TOF=0.83msec

Event selection in Super-Kamiokande

Decay electron cut

500msec

Evis > 20MeV

No activity in outer detector

Event vertex in fiducial volume

Evis > 30MeV

5msec

108 events obs’d

Analysis time window

150.9 events exp’d

TDIFF. (ms)


Summary of k2k sk events
Summary of K2K-SK events

K2K I+II

preliminary


K2k energy spectrum based on single ring m like events

preliminary

MC (no osc.)

Number of events

MC (osc.)

Enrec[GeV]

Deficit of events

K2K energy spectrum (based on single-ring m-like events)

MC normalization: number of events


Best fit oscillation parameters

preliminary

Best fit oscillation parameters

  • Best fit values.

    sin22q = 1.53

    Dm2 = 2.1210-3 eV2

  • Best fit values in the physical region.

    sin22q = 1.00

    Dm2 = 2.7310-3 eV2

    DlogL=0.64

Dm2

Toy MC

14.4%

2.73

sin22q=1.53 can occurr due to a

a statistical fluctuation with 14.4% probability.

1.00

1.53

sin22q


Allowed parameter region

90%CL

preliminary

Dm2[eV2]

SK (L/E)

K2K

SK(zenith)

sin22q

Allowed parameter region

Best fit values (in the physical region)

sin22q = 1.00

Dm2 [eV2] = 2.710-3

Dm2=(1.7~3.5)×10-3 eV2

(90% C.L.) @ sin22q=1.0


T2K experiment

Super-Kamiokande

JAERI

T2K

250km

J-PARC

K2K

Collaboration (at present): Canada, China, France, Italy, Japan, Korea, Poland, Russia, Spain, Switzerland, UK, USA


T2k main physics goals
T2K main physics goals

1st phase

  • Discovery of non-zero q13

  • Precise measurement of sin22q23 and Dm232(Discovery of non maximal q23?)

If q13≠0 observed

2nd phase

  • Discovery of non-zero CP phase


J parc facility

50GeV

50GeV dipole magnets

Nuclear and Particle

Experimental Facility

Materials and Life Science

Experimental Facility

Nuclear Transmutation

3GeV

Neutrino to Kamiokande

3 GeV Synchrotron

(25 Hz, 1MW)

50 GeV Synchrotron

(0.75 MW)

Linac

(350m)

LINAC

J-PARC = Japan Proton Accelerator Research Complex

J-PARC Facility

Under construction, expected completion (Phase-I)= end 2007


T2k neutrino facility

OA0°

OA2°

OA2.5°

OA3°

T2K neutrino facility

Off axis n beam facility

To SK

Near detectors (280m,

and 2km(not approved yet)


Measurement of d m 2 and sin 2 2 q 23
Measurement of Dm2 and sin22q23

Data sample: SK Monte Carlo, Fully-contained single-ring, muon-like events.

π

π

Event fraction

En from Em and qm

Typical JHF neutrino energy

Important to run the experiment with low energy beam.


Reconstructed neutrino energy distribution

~ OA 2.5 deg. ~

No oscillation

Dm2= 2.5 x10-3 eV2

Quasi Elastic

non-QE

reconstructed En (GeV)

reconstructed En (GeV)


Precise measurement of q23 , Dm223

normalization

( 5%)

non-qe/qe ratio

( 5%)

Assumed systematic errors

E scale

( 1%)

Spectrum shape

(20%)

Spectrum width

( 5%)

d(Dm223)

<1×10-4 eV2

d(sin22q23)~0.01

TrueDm232(10-3eV2)

TrueDm232(10-3eV2)


Present status:

q13

Allowed

sin2q13

Signal for non-zero q13 (nmne)

BG (NC p0 ….)


Measurement of n m n e

exp’d signal+BG

total BG

nm BG

50

Number of events

0

0

1

2

3

4

5

reconstructed En(GeV)

Updated

Measurement of nmne

10-1

Expected signal for

DBG=10%

CHOOZ limit

10-2

Dm2 (eV2)

10-3

10-4

10-3

10-2

10-1

1

sin22q13

More details: K.Kaneyuki’s talk


T2k phase ii
T2K Phase-II

★0.77 → 4 MW beam power

★~1 Mton detector (Hyper-Kamiokande)

106 events (both nm and anti-nm)

CP Violation


Assumptions
Assumptions

(not updated to the most recent solar parameters)

Solid line: w/ matter

Dashed line: w/o matter


Expected CP violation signal (example)

Neutrino run=2years, anti-neutrino run=6.8years, 4MW, 0.54Mton fid. Vol.

sin22q13=0.1

Dm31<0

3s stat only

3s stat+2% syst.

# of e+ events including BG

90%C.L. stat only

90%C.L. stat+2% syst.

Dm31>0

CP phase

# of e- events including BG


3 s cp sensitivity
3s CP sensitivity

CHOOZ excluded

sin22q13<[email protected]~3x10-3eV2

sin22q13

stat+5%syst.

stat+2%syst.

(signal+BG) stat only

stat+10%syst.

no BG

signal stat only

JHF-I: No indication for sin22θ13

sind

3s CP sensitivity : |d|>20o for sin22q13>0.01 with 2% syst.


Neutrino facility construction

Expected completion: early 2009

Beam Transfer line from 3GeV to

Material and Life science Facility)

OA2o

OA3o

Target

Station

~15m

Decay Volume ~110m

Dump

~10m

Construction started


Summary

  • Present atmospheric neutrino data from SK are nicely explained by nm nt oscillations with;

    Dm2=1.9 – 3.0 × 10-3 eV2

    sin22q > 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 accelerator beam.

  • Neutrino oscillation results from K2K are in good agreement with the SK results.

  • T2K, a precision neutrino oscillation experiment, will start in 2009.

  • If non-zero q13 is observed in T2K phase-I, we would like to proceed to T2K phase-II to measure the CP phase.



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