The Experiment Patrick de Perio - McGill Physics · 2012. 2. 24. · at 2.5σ, subsequent results...

The Experiment – Patrick de PerioPatrick de Perio

February 24, 2012

Tokai, Japan東海村、日本

Kamioka, Japan神岡、日本

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February 24, 2012

Neutrino Oscillation

• Neutrino flavor content varies as it propagates through space, through mixing of the mass eigenstates

2( ) ( ) ( )2 2 2

23 23sin 2 sin 4xP m L Eµ νν ν θ→ ≈ ∆

=

3

2

1

ννν

ννν

τ

µ PMNS

e

U

37° < θ23 ≤ 45°Δm23

2 = (2.4±0.5)x10-3 eV2 θ13 < 11°θ12 = (33.9±1.4)°

Δm122 = (8.0±0.3)x10-5 eV2

Atmospheric& Accelerator

Reactor& Accelerator

Solar &Reactor

( ) ( ) ( ) ( )2 2 2 213 23 23sin 2 sin sin 4eP m L Eµ νν ν θ θ→ ≈ ∆

νe appearanceθ13 < 2°δ(θ23) < 2°

δ(Δm232) < 0.1 x 10-3 eV2

T2K

Goa

lCu

rren

t

νμ disappearance

Measurement of CP phase δ depends on size of θ13

13 13 13

13 1

12 12

123 23

2

2 1

33

2

23

00 1

0.8 0.50.4 0.6 0.70.4 0.6 0.7

0

0

00

0 0

100 1

0 0 i i

iPMNS

c scU

e s e

s e c

c

s

sss

cc

δ δ

δ

+ +

+ + − +

+ + − +

= ≈

− +

February 24, 2012 Patrick de Perio - The T2K Experiment - WNPPC

Overview of T2K

3

νμ beam

Far Detector (FD): Super-Kamiokande Accelerator: J-PARCFebruary 24, 2012 Patrick de Perio - The T2K Experiment - WNPPC

ν μbe

am

Near Detector (ND): ND280

Calculating # of Events and Oscillation Parameters

4

( )e oD scFD

F dEPµν ν νσ εφ ⋅ ⋅ ⋅ ⋅∫

Neutrino Flux

• Prediction from MC simulation

• Understanding of the proton beam and hadron production

Cross Section

• Input from theoretical calculation and previous experiments

• Large uncertainties

Efficiency

• Detector performance

• Event reconstruction and selection

Measurements

• used to normalize prediction at FD

• fitted to the number of observed events at the FD, , to extract the oscillation parameters:


dataexp MC

MCND

FD FDND

NN NN

=

( ) ( ) ( )( ) ( ) ( ) ( )

2 2 223 23

2 2 2 213 23 23

1 sin 2 sin 4 , disappearance

sin 2 sin sin 4 , appearanceosc

e e

P m L EP

P m L E

µ µ ν µ

µ ν

ν ν θ ν

ν ν θ θ ν

→ ≈ − ∆= → ≈ ∆

Number ofinteractions

dataNDN

expFDN

dataFDN

νν εσφ dEN SKMCSK

null ⋅⋅⋅= ∫

Neutrino Beamline

• Geant3/FLUKA MC based flux prediction

• Based on measurements– External: Hadron production

experiments (NA61 and others)– In-situ: Proton beam monitors

5

0.6 GeV = T2K <Eν>


oscPφ σ ε⋅ ⋅ ⋅

Neutrino Interactions• Event

generatorMC basedon theoretical cross section calculations and tuning from external data

• Reconstruct Eν and flavour from observed lepton in CCQE interactions

6

ν

NN’

ν’(l±)π

NC(CC) π

Z(W)Δ

0.6

ν

N N’

CCQE

Wl±

CC



lllN

llNpEmmEmE

θν cos2/2

+−−

≈

l

Nνl

θlCCQE

Pion Final State Interactions• Affects background

contribution to CCQE sample• Final state interactions (FSI)

simulated by microscopic cascade model

7

Incoming νπ

Outgoing l

Outgoing n

Scattered π

Absorbed π

π



• Tuned and constrained with external pion scattering and photoproduction data

dataexp MC

MC ,NDFD FD

ND

NN NN

=ND280• Select νμ CC candidate events

from reconstructed μ-

• Use data/MC integrated rate ratio to normalize expected number of events at SK

• Future: Neutrino cross section measurements

8

P0D ECAL

Barrel ECAL

Ds E

CA

L

μ-

pCCQE-like event

R(data/MC) = 1.036 ± 0.028 (stat)+0.044

-0.037 (detector syst.)± 0.038 (xsec model syst.)

Dataset from 2.88 x 1019 POT



Super-K• 50 kton water Čerenkov

detector• 1 km underground• 11k PMTs in ID• Event reconstruction:

See Shimpei Tobayama’stalk tomorrow

9

µ e

Timing of events corresponds to beam timing from GPS


oscPφ σ ε⋅ ⋅ ⋅data ,FDN

`

10000000

lllN

llNpEmmEmE

θν cos2/2

+−−

≈

l

Nνl

θlCCQE

µ e

Oscillation Analysis

• Select fully contained events in fiducial volume

• 1-ring, μ or e-like

• Perform fit to extract oscillation parameters

February 24, 2012 Patrick de Perio - The T2K Experiment - WNPPC 10sin2(2θ13)

δ CP

@ 90% CL:

sin2(2θ23)

Δm23

2(e

V2 )

Reconstructed neutrino energy (GeV)Reconstructed neutrino energy (GeV)0 1 2 30 1 2 3 4

@ 90% CL:sin2(2θ23) > 0.852.1 < Δm23

2 (eVx10-3) < 3.1

νe appearanceνμ disappearance

31 νμ CCQE-likecandidates

6 νe CCQE-likecandidates

0.03<sin2(2θ13)<0.28

(1.43 x 1020 POT)

( ) ( ) ( )2 2 223 23sin 2 sin 4xP m L Eµ νν ν θ→ ≈ ∆ ( ) ( ) ( ) ( )2 2 2 2

13 23 23sin 2 sin sin 4eP m L Eµ νν ν θ θ→ ≈ ∆

dataexp MC

MC ,NDFD FD

ND

NN NN

= oscPφ σ ε⋅ ⋅ ⋅0data ,FDN

Signal

Bkg = 1.49

Conclusions and Prospect• Results with only 2% of design POT:

– νμ disappearance measurement rejects null-oscillation at 4.5σ, consistent with MINOS, SK and K2K

– νe appearance first indication of non-zero θ13 at 2.5σ,subsequent results from MINOS and Double Chooz are consistent

• Continuous beam running will resume (after the earthquake) in March

• Improvements to analysis and systematics

• Neutrino cross section measurementsby ND280

February 24, 2012 Patrick de Perio - The T2K Experiment - WNPPC 11

`First events after

earthquake

The T2K Collaboration Thank you and stay tuned…

Proton Beam Monitors

14

POTMCSK ⋅→ − ][ 1POTφφ

CT (intensity)



OTR Proton Beam Monitor• Measures beam

position and width at the target

• Strong constraint on the resulting ν-beam direction

15

PositionCalibration

Camera

Filament light source

Optical Transition

Radiation



Off-axis Neutrino Beam



On-Axis Neutrino Detector: INGRID

• 16 modules arranged in a cross– X-Y iron-scintillator layers, 7.1 tons each

• Count neutrino interactions in each module to determine neutrino rate vs. position

• Extract beam direction better than 0.5 mrad



νe Appearance Backgrounds


π0


νe Event Selection



νe Event Vertex Distributions


Clustering of candidates at high R in beam directionKS test of R2 variable is 3%(does not include beam

dir)

All FC Events

νμ Event Selection



Beam and Interaction Uncertainties



Uncertainty(after ND scaling)

νμ signal νe bkrd

CCQE nuclear model (@lowE) 2.5% 3.1%

CC1π +0.4% -0.5% 2.2%CC coherent π - 3.1%CC other +4.1% -3.6% 4.4%NC all 0.9% -NC1π0 - 5.3%NC coherent π - 2.3%NC other - 2.3%σ(νe) N/A 3.4%Final State Interactions (FSI) 6.7% 10.1%

Total +8.3%-8.1% 14.0%

Flux uncertainties ND νe bkrd νe / NDProton beam 2.2% 0.0% 2.2%Pion production 5.7% 6.2% 2.5%Kaon production 10.0% 11.1% 7.6%Other hadronicinteractions 9.7% 9.5% 1.5%

Meson focusing, beam direction 2.8% 2.2% 0.8%

Total 15.4% 16.1% 8.5%

νe Analysis Summary



Far detector uncertainties (%)

νe signal νebkgd

Ring counting 3.9% 8.3%

Electron PID 3.8% 8.0%

Invariant mass 5.1% 8.7%

π0 rejection - 3.6%

Fiducial volume 1.4% 1.4%

Energy scale 0.4% 1.1%

Decay electron eff 0.1% 0.3%

Muon PID - 1.0%

Total 7.6% 15%

Background # eventsbeam νe 0.76

νμ CC background 0.03

NC background 0.61

osc through θ12 0.09

Total 1.49±0.34(sys)

Signal (νμ to νe osc) # events@sin22θ13=0.1, δcp=0 4.11

Uncertainties νe bkrd νe sig+bkrd

ν flux ±8.5% ±8.5%

ν interactions ±14.0% ±10.5%

Near detector +5.6 -5.2% +5.6 -5.2%

Far detector ±14.7% ±9.4%

Total +22.8 -22.7% +17.6 -17.5%

Earthquake Damage



3 GeV synchrotronpower station

LINAC Neutrino Hall AC Neutrino beam dump

Road near 3 GeV RCS

http://www.kek.jp/intra-e/Introduction/column/110509map.html

The Experiment Patrick de Perio - McGill Physics · 2012. 2. 24. · at 2.5σ, subsequent results...

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