T2K experiment Takashi Kobayashi - PowerPoint Presentation

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T2K experiment

Takashi KobayashiKEKfor T2K collaboration

Mar.14,2013nTelescopes 2013Venice

30min talk including discussion

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The T2K Collaboration(~500 members, 56 institutions, 11 countries)

Canada

TRIUMF

U. Alberta

U. B. Columbia

U. Regina

U. Toronto

U. Victoria

U. Winnipeg

York U.

France

CEA

Saclay

IPN Lyon

LLR E. Poly.

LPNHE Paris

Germany

U. Aachen

ItalyINFN, U. BariINFN, U. NapoliINFN, U. PadovaINFN, U. RomaJapanICRR KamiokaICRR RCCNKEKKobe U.Kyoto U.Miyagi U. EducationOsaka City U.U. Tokyo

PolandIFJPAN, CracowNCBJ, WarsawU. Silesia, KatowiceU. WarsawWarsaw U.T.U. WroklawRussiaINRSpainIFAE, BarcelonaIFIC, Valencia

USABoston U.Colorado S. U.Duke U.Louisiana S. U.Stony Brook U.U. C. IrvineU. ColoradoU. PittsburghU. RochesterU. Washington

SwitzerlandU. BernU. GenevaETH ZurichUnited KingdomImperial C. LondonLancaster U.U. LiverpoolOxford U.Queen Mary U. L.U. SheffieldSTFC/DaresburySTFC/RALU. Warwick

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T2K (Tokai to

Kamioka) experimentHigh intensity n

m beam from J-PARC MR to Super-Kamiokande @ 295kmDiscovery



Measurement of

n

e

appearance

Precise meas. of

n

m

disappearance 

q

23

, D

m23

2Really maximum mixing?Now least known mixing angle

Slide4

History

1999: Nishikawa&Totsuka

proposed to measure ne appearance as a next critical step toward CP measurementFeb. 2000: LoIApril 2004:Officially approved by Japanese Government and 5yr Construction started

T2K international collaboration officially formedSpokesperson: K.Nishikawa

April 23, 2009: First neutrino beam production and commissioning started

January 2010: Data accumulation for oscillation search started!

Mar.11,2011- shutdown due to Earthquake damage

June 2011: First 2.5

s

evidence o

n

e

appearance

Dec. 2011:

Acc resumed operationMar.2012: T2K resumed data taking

June/July 2012: 3.2s n

e appearance results

4Y.Totsuka (1942~2008)K.Nishikawa

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5

30GeV proton beam from J-PARC

MR to produce neutrino beamBeam is 2.5 deg off-axis from far detector directionPeak ~0.6GeV @ osc. max

Small high energy tailDominated by Ccqe

 Low background

Muon monitors @ ~120m

Near detector

@280m

On-axis detector “INGRID”

Off-axis (toward SK direction)

Far detector Super-

Kamiokande

@ 295km

Overview

p

p

n

120m0m280m295 km

on-axisoff-axis2.5om-monNear detectors

Super-Kamiokandew/o osc.

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60km

JAEA

J-PARC

Japan Proton Accelerator Research Complex

Located in Tokai-village, 60km N.E. of KEK

Completed in 2009

MR

1567.5

m circum.

Tp

= 30GeV

8 bunch (h#=9)

Rep cycle: 2.48sec (now)

Design goal

RCS: 1MW

MR: 750kW

MR achieved 230kW stable operation for neutrino experiment

6Joint project of KEK & Japan Atomic Energy Agency (JAEA)

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7

Neutrino facility for T2K at J-PARC

Target

Primary beamline (superconducting)

Electromagnetic horn

Neutrino monitor bld.

7

Muon monitors

Fast Extracted (FX) beam from MR

@ 30GeV

8 bunches 581ns apart

Proton beam transport

Superconducting combined function magnets

Graphite target (26mm

f

x90cm)

3 horns @ 250kA

117m of decay volume (from target)SK direction is given by GPS survey at 2mrad precision

Slide8

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The T2K near detector complex

On-axis: INGRID

Off-axis: ND280

ν

beam

profile

and

direction

monitor

14 iron-scintillator modules span a 10x10 m

2

surface

beam

center:

ν

flux

norm./spect.

, cross-sectionsinside UA1 magnet (0.2 T):2 fine-grained detectors (FGD)water/carbon target3 gas TPCsπ0 detector (P0D)electromagnetic calorimeter (ECal)instrumented magnet yoke: SMRD

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T2K Far Detector: Super-Kamiokande



ICRR, Univ. of Tokyo

50kt Water Cherenkov detector operational since 1996

Fiducial

mass for T2K analysis:

22.5kton

11129

20" PMTs in inner detector (ID), 1885 8" PMTs in outer detector (OD

)

Beam

related events are selected by event timing using GPS system.

High PID (e/

m

) capability based on Cherenkov light distribution

PID likelihood

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Data taking history

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RUN1+RUN2: 1.43 x 1020 POT

 6 ne

evts

2.5

s

n

e

app.

+ RUN3: 3.01 x 10

20 POT

 11 ne

evts 3.2s

ne app.

+ RUN4 (-Mar.6): 5.63 x 1020 POT

 ~ 7% of the total approved POTStable operation @ 230kW (1.2x1014p/p~1.5x1013p/b) reached!Jan2010RUN1RUN2Great East Japan Earthquake (Mar. 11, 2011)RUN3RUN4ne appearance results~230kW

~120Tpppnm disappearance resultNew nm disapp (Feb.2013)Evidence

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11

Beam stability

Profile center by

muon

monitor

Neutrino event rate by INGRID

Neutrino beam profile center by INGRID

All are stable well within our requirements

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Latest status

Data is being collected very smoothly

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Analysis Strategy

Predict SK observations (

nm, ne): N

m/e(

p

n

,

P

osc

)

BASED ON T2K (ND280) &NA61 measurements

as precisely as necessary

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Flux at SK

Osc

. Prob.

Cross sect.Det. Eff.SK Det. Responcepnrec: Measured kinetic variables of n eg. En or (pn,qn)Entrue: True neutrino energy

Then compare w/ SK observation  Measure excess or constrain oscillation parametersFluxND280 meas.ConstrainT2K&Other cross section data

ConstrainInteraction/nucleus/FSI model(norm/shape)Hadron prod data(NA61, other data)

ExtrapolationConstrain(mainly shape)Constrain

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Beam flux prediction

Flux & Near to far flux extrapolation are governed by parent

hadron (p/K..) production (p&q dist.)Beam line geometry (controllable)

Hadron production measurements by NA61/SHINE have been critical for T2K

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NA61 (

S.d.Luise@ICHEP

)

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Beam flux prediction

GEANT3 simulation

of neutrino production from graphite target

pion and

kaon

production tuned to experimental data (

NA61

)

Normalisation

in bins of

E

ν

and

ν

flavour

1510-15% total error(before ND280 constraints)PRD87 (2013) 012001

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ND280 measurements

Divide ND280 data

into two samples binned in

pμ

vs

θ

μ

:

Charged current quasi-elastic (

CCQE

)-enhanced:

ν+n→μ+p

Charged current non quasi-elastic (

CCnQE

)-enhanced: producing

one or more π16CC selection in tracker region: at least one negative track, μ candidate originating in the near detector tracker region Additional CCQE selection: only 1 FGD-TPC track, no Michel electron in FGD1after fittingGives constraints on F x

ss

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Impact of ND280m measurements

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On prediction of

ne

appearance (# of events, systematic error)

On prediction of

n

m

disappearance (# of events, systematic error)

w/o ND constraint

w ND constraint

w/o ND constraint

w ND constraint

# of

n

m

evtsEn spec. shapeND280 also playing fundamental role!

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Results from the T2K

nm disappearance

Oscillation Analyses2011 results based on Run 1 + 2

(1.43 x 1020 POT

)

Phy

s. Rev. D 85, 031103(R), 2012

(

arXiv:1201.1386

)

New Results

based on

Run1 - 3 data (3.01

x

10

20 POT)Use event rate and E

rec spectrum (Same as before)New analysis w/ spectrum constraint by ND280

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19

only

1 ring

PID

is

muon

-like

Reconstructed

momentum

greater than

200 MeV/c

Number of

decay electrons ≦1

ν

μ

event selection at the T2K far detector

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Oscillation Analysis

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vary oscillation parameters until best fit is found

E

xtended Maximum

Likelihood

Binned Likelihood Ratio

Fit reconstructed

energy spectra

of single-ring μ-like events with predicted spectra, in a

3-flavour mixing

context

Ingredients:

MC templates

from

flavour

/interaction type:

flavour

: νμ, νμ, νe, νe, oscillated νeinteraction: CCQE, CC1π, CC coherent, CC other, NC1π±, NC otherquasi-elastic reaction kinematics to reconstruct neutrino energyestimates

of flux and cross-section parameters, with errors and correlationnon-32 oscillation parameters: = Determination

of θ23 and Δm322

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Fitting results

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Binned Likelihood Ratio

Best fit

Best fit

21

best fitted spectrum

non oscill. spectrum

●

Run 1-3 data

best fitted spectrum

●

Run 1-3 data

Extended maximum likelihood

fit

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Determination of νμ

oscillation parameters

All the results together in the same plot:

World best precision on

q

23

!!

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Effect of systematic error

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Constraint

Constraint

Sensitivity plot

(3.01x10

20

POT)

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Results from the T2K

ne appearance

Oscillation Analyses (ICHEP 2012)11 candidate events are observedN

exp = 3.22±0.43 for sin

2

2

θ

13

= 0

Expected BG

2.92

events

The probability (

p

-value) to observe 11 or more events with

θ

13 = 0 is 0.08% (3.2σ)T2K saw first indication of non-zero q13 in 2011 and now established an evidence of ne appearance from nm which is a necessary condition for us to explore CP violation in the lepton sector  By summer 2013, we aim to achieve ~5σ “Observation” of ne appearance from nmFinal Selected Events24

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Allowed Regions (ICHEP2012)

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T2K ND cross section

measurementsA lot more to come!

CCqe, CC1p±, CC1p0, NCela, NC1

p±, NC1p

0

, DIS

Will also help further reduce the systematic errors on oscillation parameters

(P0D) NC1p

0

CC inclusive

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(ICHEP2012)

(ICHEP2012)

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Future prospect

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T2K program

Establish

APPEARANCE ~5s level before 2013 Summer shutdownPrecision measurement of appearance

Compare with reactor resultsTry to see first hint on CPV and mass hierarchyMeasurement of Dm

13

Precision measurement of disappearance

q

23

,

D

m

23

Whether maximal mixing or not?Important for probing CPVSterile neutrino searches

Pursue possibility of anti-nu measurementsVarious cross section measurements at near detector

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From discovery of 3 flavor mixing to precision meas.

 Start probing CPV & Mass hierarchy

29Appearance probability

(T2K observable)

Rough T2K stat err (±1

s

)

Rough T2K stat err (±1

s

)

T2K approved POT

=

7.8x10

21

POT (equiv.

750kW x 5 x10

7

sec)

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Accelerator upgrades

Based on operation experiences and beam simulations, it is getting clear that beam loss at MR injection will limit #p/b <~ 3x10

13 (1.5x1013 now, design was 4.1x1013)

Path to design MR power (750kW)Higher #p/b (x~2)Higher rep rate (2.48  1.28s, x~2)

Double #p/b

LINAC frontend upgrade (2013 Summer)

Ion source, RFQ : 30mA

 50mA

RCS 400MeV injection

Capable to operate RCS

upto

1MW (300kW at present)

MR RF (higher harmonic)

Double rep rateReplace all MR magnet power supplies (~5yrs)

High gradient RF core

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Present MR power & loss

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J-PARC power upgrade plan (I)

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MR beam power = [RCS power] x (30GeV/3GeV) x {8bnch/(2x25HzxTMR)}

= 0.64 x [RCS power] @ MR 2.48s cycle = 1.25 x [RCS power] @ MR

1.28s

cycle

Now, due to Ion source life time, RCS power is limited ~350kW for long term stable operation

 MR power is limited 350kW x 0.64 ~ 230kW

Now

After upgrade of IS, RFQ, LINAC energy in 2013, RCS power can go

upto

1MW

J-PARC IAC

Hasegawa,

Feb.2013

This

year

LINACIon source & RFQEnergy upgrade to 400MeVRCS400MeV inj.

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J-PARC power upgrade plan (II)

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J-PARC A-TACKoseki

, Feb.2013

MR wil

l increase rep rate

upto

~1.28s

Replace all magnet power supply

RF accelerating power upgrade

Upgrade of related pulse operation devices (inj./ext. kicker/septum

etc

)If Power Supply is funded as we planned, MR will be capable of ~750kW or higher around ~2017

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Summary

T2K resumed data taking in Mar.2012 after ~1yr shutdown caused by the EQAccumulated ~5.6x10

20POT by Mar.6,2013, achieved 230kW stable operationne appearance results (ICHEP2012)11 ne

candidate found (3.22 exp’ed w/ q13=0)

3.2

s

significant excess beyond 3.22

New results of

n

m

disappearance is released recently with 3.01x10

20

POT taken before Summer 2012Max mixing &

Dm232=2.45x10

-3eVWorld leading measurement on mixing angleAim to establish

ne APPEARANCE

at 5s level by this SummerStart to probe CPV & mass hierarchy by

improving precisions of ne appearance & nm disappearancecomparison with other experiments such as reactors, NOvA, SKAccelerator upgrades are planned to realize O(MW) operation within time scale of ~5yr33

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Spare slides

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Projected Integrated POT Delivered to T2K

T2K approved total integrated POT is: 7.8x10

21 POT (5 year run @750 kW)

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