Recent results from T2K
Yoshinari Hayato
for the T2K collaboration

Introduction
Neutrino oscillation ~ discovered in 1998 & extensively studied.
Flavor mixing & non-zero neutrino mass
~ Beyond the standard model ~• 3 oscillation angles(q12, q23, q13)
• 2 mass differences(Dm212, Dm232)• 1 CP phase (d)Parameters

PMNS Matrix (Uai)|na> = SUai|ni>
Weak

Mass eigenstates

sij=sinqij, cij=cosqij

U=
Atmospheric& Accelerator

Reactor& Accelerator

Solar& Reactor

6
4 2s
2

Neutrino oscillation parameter measurements-52( Atm. + Accl. )Dm in 10 eV21s

sin22q23 > 0.9| Dm232 |~ 2.5 ± 0.2 x 10-3
(eV/c2)2

18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2

(Solar + Reactor)
sin2q12 ~ 0.305±0.013
Solar νexperiments
KamLAND

Dm221= 7.49 +0.19-0.17 x10-5 (eV/c2)2

0.1( Reactor + Accl. )sin22q13= 0.098 ± 0.013
Daya-Bay collaboration
PRL 112 (2014) 061801
sin22q13 = 0.090+0.008-0.009

0.2

0.3

0.4

0.5
2
sin (q12)

1s

Neutrino mixing parameter measurements
Remaining issues
1) q23 is really 45o or < 45o or >45o ?
Current uncertainty of sin2q23 is still large
2) CP is violated or not ( d = 0 or not ) ?
3) Mass hierarchy ~ which is heavier ? ( Dm232 > 0 or < 0 ?)Normal hierarchy

Inverted hierarchy−𝟑 eV/c 𝟐
𝚫𝐦𝟐𝟐𝟏 = 𝟕. 𝟒𝟗+𝟎.𝟏𝟗−𝟎.𝟏𝟕 × 𝟏𝟎𝚫𝒎𝟐𝟑𝟐
~𝟐. 𝟓 ± 𝟎. 𝟐 × 𝟏𝟎−𝟑 eV/c 𝟐

𝟐

𝚫𝒎𝟐𝟑𝟐
~𝟐. 𝟓 ± 𝟎. 𝟐 × 𝟏𝟎−𝟑 eV/c 𝟐−𝟑 eV/c 𝟐
𝚫𝐦𝟐𝟐𝟏 = 𝟕. 𝟒𝟗+𝟎.𝟏𝟗−𝟎.𝟏𝟕 × 𝟏𝟎

𝟐

𝟐

𝟐

Tokai to Kamioka long baseline
neutrino oscillation experiment ( T2K )Tokai to Kamioka long baseline
neutrino oscillation experiment ( T2K ) Search for the ne appearance
 measure q13
 Precision measurements of oscillation parameterswith nm disappearance
 d(Dm223) ~ 1x10-4 eV2 , d(sin2 2q23) ~ 0.01
 Study CP violation in the lepton sector ( & mass hierarchy )Neutrino mixing parameter measurements in T2K
nm disappearance channel~ precise measurement of q23 & Dm232 / Dm213
Expected sensitivityd(Dm223) ~ 1 x 10-4 eV2 , d(sin2 2q23) ~ 0.01

To achieve this precision,high statistics & small systematic errors are required.
nm Survival probabilityP(nm ® nm)

𝑷 𝝂𝝁 → 𝝂𝝁 ≃ 𝟏 − ( 𝐜𝐨𝐬𝟒 𝜽𝟏𝟑 𝐬𝐢𝐧𝟐 𝟐𝜽𝟐𝟑 + 𝐬𝐢𝐧𝟐 𝟐𝜽𝟏𝟑 𝐬𝐢𝐧𝟐 𝜽𝟐𝟑 ) 𝐬𝐢𝐧𝟐 𝚫
1

00

U.)

sin22q23 = 1.0
Dm 232 = 2.4 ´ 10-3 eV2

0.5

11

2
Δ = Δ𝑚32
𝐿/ 4𝐸 ( Normal hierarchy )2
Δ𝑚13
𝐿/ 4𝐸 ( Inverted hierarchy )22 En ( GeV ) 3
1
OA 0.0°
Oscillation maximumOA~ 600
2.0° MeV @ 295km
OA 2.5°

Neutrino mixing parameter measurements in T2K
ne appearance channel~ precise measurement of q13
𝑷 𝝂𝝁 → 𝝂𝒆 = 𝐬𝐢𝐧𝟐 𝟐𝜽𝟏𝟑 𝐬𝐢𝐧𝟐 𝜽𝟐𝟑 𝐬𝐢𝐧𝟐 𝚫𝟑𝟏( leading term )CP violating term

sin22q13=0.1

For anti neutrinos,
a → -a, d → -d

p/2
p
-p/2

Neutrino mixing parameter measurements in T2K
ne appearance channel~ Study of CP violation in lepton sector
Two methods
Use q13 constraints from reactorne disappearancensin22q13=0.1
p/2
p
-p/2

anti-nsin22q13=0.1

Compare difference between n andn oscillations
T2K is planning to run with anti-neutrino configuration ( flip horn current ).
Anti neutrino “test run” is planned in 2014.

p/2
p
-p/2

T2K neutrino beam ~ Off axis beam ~Maximize sensitivity in oscillation studies
Use narrow band beam with peak energy
at the oscillation maximum

Off axis beam(ref.: BNL-E889 Proposal)

Important to monitor beam direction!
( 1mrad ~ peak En shifts by ~16 MeV )Far detector
Decay
Targetsin22q23 = 1.0
Dm 232 = 2.4 ´ 10-3 eV2

0.5

1

2

n beam energy can be tuned
by changing the off-axis angle.
OA 2deg

3

OA 0.0°OA 2.0°OA 2.5°

1

0.8
0.4

1

0

F295km
(A.U.)nm

En (GeV)q ( Off axis angle )

Pipe

Horns

P(nm ® nm)• Quasi-monochromatic beam ~ suppressed high energy n• Energy is tunable ( Change off axis angle )0.5

OA 3deg2

4

6

Pp (GeV/c)

0
0

0

1

2

1 E (GeV) 2n33

T2K ~ Schematic diagram of the experiment• Proton beam extracted every ~ 2.5 sec.
• Beam spill width ~ 5 ms
~5ms
8 bunches ( 6 bunches before Summer 2010 )~3 s• Neutrino production target
graphite target( diameter = 26mm, L=90cm )~580nsHe air cooled• p focusing ~ Triple horn system~10ns
operated @ 250kA
except for short period in Run 3 ( 205kA , 0.21 x 1020 pot )Increased beam power~ achieved by increasing the # of protons per pulse & repetition rate

T2K ~ Accumulated data ~1.2 x 1014 protons per pulse !
( World record )
Run1

Run2
Run3

Run4

Beam power has been continuously increased by
1) # of protons per spill was increased and2) beam repetition rate has been shortened.
Run1(3.52s), Run2(3.2~3.04s), Run3(2.56s), Run4(2.48s)

Delivered # of protons
6.63 x 1020 protons on target
Analyzed # of protons6.57 x 1020 protons on target~ 8% of T2K goal

T2K ~ Schematic diagram of the experiment

Stability of the beam is very crucial
1mrad change of the neutrino beam direction
results in 2~3 % shift of the mean neutrino energy ( ~ 16 MeV )• Muon monitor after the beam dump
INGRID
Spill by spill monitor
of the neutrino direction
and intensity of muon
• On axis near neutrino detector
INGRID ( Fe + Scintillator )10m
Day by day monitor
of the neutrino interaction rate
10m
Neutrino beam direction monitor

T2K ~ Beam stability ~ monitored by muon monitor
Stability of beam direction is less than 1mrad
throughout whole run period

T2K ~ Beam stability ~ monitored by INGRID
Monitor the number of interactions in the detector
Interaction rate / P.O.T.
Neutrino beam center position• Observed neutrino interaction rate per P.O.T.
has been stable within 0.7%
• Neutrino beam direction is stable within 1mrad
Neutrino beam has been confirmed to be stable.

T2K ~ Schematic diagram of the experiment• Off axis detectors
neutrino flux measurements
neutrino interaction studies
UA1 magnet ( 0.2 T )41.4m©Scientific American

T2K far detector ~ Super-Kamiokande

39.3m• Water Cherenkov detector withfiducial volume 22.5kton
Inner detector (ID)11,129 20inch PMT
Outer detector (OD)
1,885 8inch PMT• New DAQ system from 2008
• Realtime recording of all PMT hits
within ±500msec of each n beam
arrival time at SK by with GPS.
~3 sec~5msecT2K experiment ~ Analysis strategy
Extracting the “oscillation parameters” from observables~ compare the data and the prediction with oscillations.
Prediction
Based on Monte-Carlo simulation with various constraints
from the measurements

ν fluxBeam simulation program( FLUKA + GEANT3 w/ GCALOR )+ p, K production data ( NA61 etc. )ν cross sections
n interaction simulation program( NEUT )+ External constraints ( data )Near detector measurements
to constrain uncertainties
of neutrino flux andneutrino interaction models

prediction in SK

T2K neutrino beam ~ flux prediction

with GCALOR

proton interaction inside the carbon target
Simulated by FLUKA2008.3d• Simulated with FLUKA 2008.3d + GEANT3 w/GCALOR• Apply weights to the flux
~ Constraint from the external hadron production data sets
CERN NA61/SHINE ( Primarily used )> 90 % coverage of n parent pions,~ 60 % coverage of n paraent kaons
Other data sets are used for outside of the NA61 coverage+ systematic error evaluations
T. Eichten et al. ( Nucl. Phys. B44 1972 )J.V. Allaby et al. ( Tech. Rep. 70-12 CERN, 1970 ) etc..

T2K neutrino beam ~ flux prediction
Beam flux predicted based on
NA61/SHINE p and K production measurements andT2K proton beam measurements
T2K run 1-4 flux at ND280

T2K run 1-4 flux at SK~ 95 % of nm at ND280 and SK are produced from p+

T2K neutrino beam ~ Uncertainty of the flux prediction
Source of uncertainties

 Uncertainties
on the flux prediction
below 15% near the flux peak.
 Uncertainties
on the ratio of the near/far ratio
less than 2% near the flux peak.

Neutrino interactions
Charged current quasi-elastic scattering
Neutral current elastic scattering
Single p,h,K resonance productions
Coherent pion productions
Deep inelastic scatteringn + N →n + N

n + N →l + N’ + p (h,K)
n + X →l + X’ + p
n + N →l + N’ + mp(h,K)(l : lepton, N,N’ : nucleon, m : integer)

Cross-sections
Total (NC+CC)

s/E (10-38cm2/GeV)n + n →l- + p

Cross-sections

CC Total
CC Total

CC quasi-elastic
DIS
CC single p
NC single p0
En (GeV)DIS (CC)Neutrino interactions in the detectors
Use charged lepton
from charged current quasi-elastic scattering ( CCQE )lnlln + n → l- + p
l

W+

nl

n

p

p

Dominant interaction
around the oscillation peak
~ flux peakcan be reconstructedfrom measured Elep & qlep

( Elep , plep )Cross-section ( fb )nqm

( Eb : Binding energy )En (GeV)Neutrino interactions in the detectors
Charged current quasi-elastic scattering ( CCQE )Fitting external data to determine the nominal and the errorof the input parameters before fitting the T2K ND280 data
CCQE cross-section(Review of Particle Properties, to appear in 2014 )Neutrino interactions in the detectors

Cross-section ( fb )Possible backgroundnm disappearancenm
mAround oscillation peakW+n + N → m- + N’ + p±
p+
proton and charged p from NC interactions ppn+N→n+pn + N → n + N’ + p±
Fraction of each interaction

True En (GeV)Neutrino interactions in the detectors
Possible backgroundne appearance
NC 1 p0 production
n + N → n + N’ + p0

nm
Z

n

p0
n

Cross-section ( fb )If one of the g from decay of p0
can not be identified,
identified as a candidate.
# of p0~ Interaction cross-section
Decay kinematics~ Momentum distribution of p0nm

Source of errors
in measuring oscillation parameters~ Need careful studies

En (GeV)Neutrino interactions in the detectors
Charged current quasi-elastic scattering ( single pion productions )Fitting external data ( mainly from MiniBooNE )to determine the nominal and the errorof the input parameters( before fitting the T2K ND280 data )Neutrino interaction measurements in the near detectors
Measure muon momentum & angular distributions in ND280
Use 3 samples ~ enrich different interaction modes
CC 0p sample

CC 1p+ sample

CCQE ~ 64%

CC 1p ~ 40%

m
TPC1

m

CC other sample
CC DIS ~ 68%

hadrons
m

p

TPC2
TPC3
FGD1 FGD2

Resonance
CCQE

DIS

Pm ( MeV/c )Pm ( MeV/c )DIS

Pm ( MeV/c )Neutrino interaction measurements in the near detectors
Fit neutrino flux and neutrino interaction model parameters
using pm – cos qm distributions of 3 samples from ND280
Constrain uncertainties on1) Neutrino flux at SK
2) Correlated neutrino interaction related parameters
CC 0p sample

Pre-fitPost-fit

CC 1p+ sample

CC other sample

Neutrino interaction measurements in the near detectors
Results from the ND280 neutrino interaction measurements
Neutrino interaction parameters

Both uncertainties on neutrino fluxand neutrino interaction parameters are well constrained.

Neutrino interaction measurements in the near detectors
Measure electron momentum & angular distributions in ND280
Use 3 samples ~ enrich different interaction modes
Interactions in FGD and particle ID in TPC
Major background: photons from p0 decays
Fit CC0p, CC1p+ + CC Other and g sideband sample

CC0πsampleCC1π+ + CC Other
sampleγ sample
fit prefers scale factorof 0.77±0.02(stat)measured n e flux
 1.06  0.06(stat)  0.08(syst)
predicted n e flux
Validation MC prediction of the intrinsic beam ne backgroundusing the data from ND280.

T2K nm disappearance analysis
arXiv:1403.1532[hep-ex]

T2K nm disappearance analysis
nm Signal events in SK
Charged current quasi-elastic scattering

MC event

nm + n → m- + p
Observed as single ring m-like event in SK.
( m-like events has sharp ring edge )Background sources
Other charged current interactions
Only m was detected.
Some of those background events
could be eliminatedby using decay electrons
for example p  m  e.
En (GeV)

protons and/or charged p from neutral current interactions

T2K nm disappearance analysis
nm Signal events in SK
Event selection criteria
Fully contained in fiducial volume
1 ring and identified as m-likeReconstructed momentum of m > 200 MeV/c
0 or 1 decay electrons
120 events are selected ( 6.57 x 1020 pot )Particle ID
RUN1-4 data

RUN1-4 data

nm /nm CCQE
nm /nm CC non-QE
ne /ne CC
Neutral current

200

100

0

1

2

3

4

Number of rings³530

Number of events

Number of events

20

nm+nm CC QE
nm+nm CC non-QE
ne+ne CCNC
(MC w/ 3-flavor osc.)(6.570´ 10 POT)
20

(6.570´ 10 POT)

20

nm+nm CC QE
nm+nm CC non-QE
ne+ne CCNC
(MC w/ 3-flavor osc.)# of decay electrons

m-likee-like

10

0

-10

0

PID parameter

10

RUN1-4 data

100

Number of events# of rings

MC event

20(6.570´ 10 POT)
nm+nm CC QE
nm+nm CC non-QE
ne+ne CCNC
(MC w/ 3-flavor osc.)

50

0

0

1

2

3

4

Number of decay-e³5

T2K nm disappearance analysis
Run 1 ~ 4 ( 6.57 x 1020 P.O.T. )Expected # of events
without oscillation= 446.0 ± 22.5 ( 𝑠𝑦𝑠𝑡. )Observed # of events= 120

Expected # of eventswith oscillation(sin2q23, Dm232)=(0.5, 2.4×10-3 eV2/c4)

Event category# of eventsnm CCQE

77.93

nm CC non-QE

40.78

ne CC

0.35

NC All

6.78

Total

125.85Reconstructed En
Data
Best fit
No oscillation

T2K nm disappearance analysis
Systematic uncertainties for # of events*( sin2q23, Dm232, dCP ) = ( 0.5, 2.4×10-3 eV2/c4, 0 )Systematics

Flux/XSEC (ND280 constraint)

Uncertainties * Binding energy and SK energy scale
are some of the dominant uncertainties
2.7%

Other XSEC

4.9%

Super-K +FSI

5.6%

Total

8.1%

affecting T2K Dm232 precision,
but they don’t appear in the left tableof # of events since they don’t affectthe overall normalization.

NSK per reconstructed energy ( bin ) with error
without ND280 constraints
with ND280 constraints

T2K nm disappearance analysis
Uncertainties from the n interactions with multi-nucleon in nucleus• Lively discussion motivated by CCQE cross section inconsistency
between MiniBooNE and the other experiment• Not incorporated directly into this analysis

Arbitrary Units– But we have a large systematic uncertainty (100%) on decays of D
resonances w/ prompt p absorption (“p-less D-decay”). It has similar
impact on neutrino energy reconstruction as a 100% uncertainty
in the multi-nucleon interaction model (Nieves model)– Dedicated MC study shows the impact on oscillation analysis
is small relative to our current statisticalerror.
CCQE
Nieves multi-N (´5)
pionless D-decay (´5)

-1

-0.5

0

0.5

QE
Ereco - Etrue (GeV)37

T2K nm disappearance analysis
Oscillation parameter fitting
Maximum likelihood fit based on# of observed events in SK ( NSK ) andreconstructed energy of neutrino ( Enrec )L = Lnorm. × Lshape × Lsyst. × Losc.

Data
Best fit
No oscillation

Constraints from the other exp’s.
sin2q12 = 0.312 ± 0.016
Dm221 = 7.50 ± 0.20 × 10−5 eV2/c4
sin2q13 = 0.0251 ± 0.0035( from PDG 2012 )** dCP is unconstrained.

Reconstructed En (GeV)T2K nm disappearance analysis
Fit results ~ allowed oscillation parameter regions
Large improvements from the previous publication.
( 3.01 x 1020 POT  6.57 x 1020 POT )Feldman-Cousins 2D confidence regions
Best fit parameters
T2K new

Previous T2K result
PRL 111, 211803 (2013)

sin2q23 [NH]([IH])

0.514( 0.511 )Dm232 [NH]
(Dm213 [IH])
eV2/c42.51( 2.48 )NSKexp [NH]([IH])

121.41( 121.39 )T2K nm disappearance analysis
Fit results ~ allowed oscillation parameter regions

sin2q23 =0.514
Dm232 = 2.51 eV2/c4
NSKexp = 121.41

sin2q23 =0.511
Dm213 = 2.48 eV2/c4
NSKexp = 121.39

F&C 1D intervals

68 % C.L.

90 % C.L.

q23 [NH][42.6°, 48.9°][40.9°, 50.7°]

q23 [IH][42.5°, 48.8°][40.8°, 50.5°]

Most precise measurement of q23~ Favors ( almost ) maximal mixing

T2K ne appearance analysis
Phys. Rev. Letter 112, 061802 ( 2014 )T2K ne appearance analysis
Charged current quasi-elastic scattering

e-like( M.C. )ne + n → e- + p

Observed as single ring e-like event
in SK
Dominant background1) ne in the beam
intrinsic background2) p0 identified as 1 ring
One g is not identified
small opening angle of 2 rings
low momentum faint ring
Search for the 1 ring e-like events
No decay electrons
not p0 like ( dedicated p0 rejection )Reconstructed En is in the oscillation regionp0( M.C. )T2K ne appearance analysis ~ event selection in SK• Fully contained event ~ no activity in the outer detector• Reconstructed in the fiducial volume ( > 200cm from the wall )• 1 ring and PID is electron-like• Visible energy ( electron equiv. energy ) > 100 MeV• No decay electrons• Reconstructed En < 1.25 GeV• special p0 identifier ( New p0 rejection )Particle ID

p0 rejection

Reconstructed En
20

RUN1-4 data

400

(6.570´ 10 POT)

20

e-like
10

0

-10

0

PID parameter

10

15

Neutral current

10

5

0
0

1000

2000

Reconstructed n energy (MeV)

3000

p0 cutMC w/
sin22q13=0.1

pm-like20(6.570´ 10 POT)
Osc. ne CC
nm+nm CC
ne+ne CCNC
(MC w/ sin 22q13=0.1)

Osc. ne CC
nm /nm CCQE
nm+nm CC
ne+ne CCnm /nm CC
non-QENC(MC
w/ sin 22q13=0.1)
ne /ne CC

fiTQun ln(L 0/Le)

Number of events

30

RUN1-4 data

Number of events

20

200

0

select

0

100

200

mg g(MeV/c(MeV/c ) )p0fiTQun
mass
2 2

300

T2K ne appearance analysis
Expected # of events and observed # of eventsin Run 1 ~ 4 ( 6.57 x 1020 P.O.T. )Expected # of events for q13 = 0= 4.9 ± 0.6 ( 𝑠𝑦𝑠𝑡. )Observed # of events = 28
Reconstructed En
Data
Best fit
No oscillation

T2K ne appearance analysis
Oscillation parameter fitting
Maximum likelihood fit based on# of observed events in SK ( NSK ) andobserved momentum and direction of electron ( pe, qe )L = Lnorm. × Lshape × Lsyst. × Losc.

Constraints from
T2K Run 1-3 results( PRL 111, 211803 ( 2013 ))andthe other experiments.

Electron momentum vs. angle distribution
θ13=0.0

θ13=0.1(MC)T2K ne appearance analysis
Expected # of events & Systematic uncertainties for # of events( sin2q23, Dm232, dCP ) = ( 0.5, 2.4×10-3 eV2/c4, 0 )Expected # of events w/ 6.57×1020 POT
sin22θ13=0.0 sin22θ13=0.1
0.40
17.30
νe signal
3.37
3.12
νe background
0.94
0.94
νμ background (mainly NCπ0)
0.21
0.20
νμ + νe background
Total
4.92
21.56
Event category

Systematic uncertainties for expected # of events
Error source

Beam flux + ν int.
constrained from ND280
ν int. (from other exp.)
Far detector+ Final state interactions+ photo nuclear effects
Total

sin22θ13=0.0 sin22θ13=0.1
4.8 %

2.9 %

7.1 %

7.6 %

7.3 %

3.5 %

11.4 %

8.9 %Expected # of events

T2K ne appearance analysis
Fit results ~ comparison with data and MC with best fit parameter
momentum vs angle

momentumangle

Exclude q13=0 at 7.3 s level
Best fit w/ 68% C.L. error:
sin2 2𝜃13 = 0.140+0.038−0.03290% allowed region:
0.090 < sin2 2𝜃13 < 0.205
With following assumptions:
δCP=0, normal hierarchy,|Δm232|=2.4×10-3 eV2 and sin22θ23=1

T2K ne appearance analysis
Allowed oscillation parameter regions Allowed regions of q13 for various dCPBest fit parameters
w/ 68% C.L. erros @ δCP=0
Normal hierarchysin2 2𝜃13 = 0.140+0.038−0.032Inverted hierarchysin2 2𝜃13 = 0.170+0.044−0.037
Constraints on the other parametersin the fit

T2K ne appearance analysis
Allowed oscillation parameter regions Allowed regions of q13 for various dCP
Comparison with q13
from reactor
From T2K
Normal hierarchysin2 2𝜃13 = 0.140+0.038−0.032Inverted hierarchysin2 2𝜃13 = 0.170+0.044−0.037

From reactor experiments( PDG 2012 )sin2 2𝜃13 = 0.098 ± 0.013
Discrepancy
Signature of non-zero dCP??

T2K ne appearance analysis
Combined fit with reactor constraints ( from PDG 2012 )sin2 2𝜃13 = 0.098 ± 0.013
dCP negative log likelihood

Regions above these lines(derived by Feldman-Cousins method)are excluded with 90% C.L.

90% excluded regions
Normal hierarchy
0.19p ~ 0.80p

Inverted hierarchy-1.00p ~ -0.97p-0.04p ~ 1.00p

Future Prospects• ne appearance and nm disappearance combined fit• Realistic (shape-dependent) systematic errors• Errors are assumed to be fully correlated between n/anti-n

Mid-term plan of MR
FX We adopt the high repetition rate scheme to achieve the design beam intensity, 750 kW."
Rep. rate will be increased from ~ 0.4 Hz to ~1 Hz by replacing magnet PS’s and RF cavities.
Mid-term plan of MR
SX After replacement of some SUS ducts to Ti ducts to reduce residual radiation dose, 50 kW
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for users
willrepetition
be started.
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schemeto willachievethe design
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Rep.
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SX After replacement of someSUS ducts
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JFY
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upgradeJFY
FX power [kW]SX power User op. study [kW]!

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Present RF system !
Install. #7,8
New highrf system!
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New magnet PS for high rep.
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Present RF system !
Install. #7,8
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New injection
Injection system!
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New injection
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Ti chamber
SX collimator
SX collimator / Local shields

2012
200 !
10 (20)2013
240 ~ (300)!
25 (30)2014~ 400!
50 (100)

201
5

2016

2017
750!
100

Li. upgrade

200 !
R&D 240 ~ (300)!
10 (20)25 (30)Install. #9
R&D

Manufacture~ 400! installation/test
50 (100)
Manufacture
installation/test
Manufacture
installation/test

R&D Add.collimators
Add.collimatorsand shields(3.5kW)(2kW) #9Install.
R&D
Add.collimatorsand shields(2kW)

Manufacture
installation/test

Add.collimators(3.5kW)
Local sheilds

Septum
ESS, "
Expected POT is estimatedbased
on theBeam
information.
endplate
Beam ducts
ducts

Local sheilds
Septum

ESS, "

Beam

750!
100

. (∼ Black
10% νeDashed:, ∼ 13% νµ with)
2012 sys. err. (∼ 10% νe , ∼ 13% νµ )2q sys.
2 1srojectederr.
7%
ν, ∼ 14% vs.
ν̄) POT
Dashed:withconservative
projected sys. err. (∼ 7% ν, ∼ 14% ν̄)
sinRed/Dm
Precision
23
32 (∼
50%
ν + 50%ν̄
100%
POTνn + 50%
POT ν + 50% POT ν̄POTPOT
fractions:
50%POT
anti-n50%
case
Dm232 1 s width

Dm232 1 s width

sin2q23 1 s width

-3

´10
0.1
Stat. Err. Only
0.09 0.14 ~2016
0.08 0.12
2012 Sys. Errs.
Full T2K POT
0.07
0.1
Projected Sys. Errs.
0.06
0.08
0.05 now
Full T2K POT
0.04 0.06
Stat. Err. Only
0.03
0.04
0.02
0.01 0.02 Projected Sys. Errs.
000
10 21 32 43 54 65 76 87 98 10
9 10

´10

-3

0.14

~2016

Stat. Err. Only

0.12
Projected Sys. Errs.

0.1
0.08
0.06

now

Full T2K POT

0.04
0.02
0
0

21
´ 10´2110
POT
POT

1

2

3

4

5

6

7

8

9

10

´ 1021 POT

Solid Lines: no sys. err.
52Dashed:conservativen is →∼Red
0.045
at withfulllimit
POTof 1σ systematic
Statisticalprecisionerrors
is ∼ (~7%4×10n,−~14%eVanti-n)
at full POT

Precisions are expected to be improved drasticallyover the next few years.
Assuming
true:at full POT
Assuming true
Statistical
limit
of
1s
precision
2 2
2
−3
◦2
2
−3
2

= 0.5,∆meVNH θ23 = 0.5, ∆ m 32 = 2.4 ×10 eV , NH2θ
0.1,
δCP (=~2.6°)
0 , sin
2q
13= =2.4
32
• sin
sin
~×10
0.045
23 (q23)2
2θ13-5) eV= 20.005 θ13 constrained by δ(sin2 2θ13 ) = 0.00
• Dm232 by δ(sin~ 4×10
3 constrained
9 / 22

Assuming true: sin22q13=0.1, dCP=0°, sin2q23=0.5, Dm232=2.4×10-3 eV2,
Normal hierarchy, q13 constrained by d(sin22q13) = 0.005

Appearance 90% C.L. Sensitivity
7.8×1021 POT ( POT fractions : 50% n + 50% anti-n)
Solid Lines: no sys. err., Dashed: with 2012 sys. err. (~10% ne, ~13% nm)
Case study (1): True dCP = 0°Case study (2): True dCP = -90°

T2K only

T2K
w/ Reactord(sin22q13)= 0.005[NH] Normal hierarchy, [IH] Inverted hierarchy
Assuming true: sin22q13=0.1, sin2q23=0.5, Dm232=2.4×10-3 eV2, [NH]

Sensitivity for Resolving sindCP≠0
7.8×1021 POT ( POT fractions : 50% n + 50% anti-n)

T2K
forsin [IH]
δCPInverted= 0 hierarchy= 0
δCP Sensitivity
vity for Resolving sin[NH]Resolving
Normal hierarchy,

True

True
NH
[NH]
150

-150

-100

10
9
8
7
6
5
4
3
2
1
0
-50

sin2q23=0.40
sin2q23=0.45
sin2q23=0.50
sin2q23=0.55
sin2q23=0.60

10
9
8
7
6
5
4
3
2
1
0

sin q23=0.40
sin2q23=0.45
10
sin2q23=0.50
9
sin2q23=0.55
87
sin2q23=0.60

D c2

D c2

True

True
IH
[IH]
dCP

1s

1s

-150 0 -10050 -50100 0 150 50

2

150

90%

dCP

dCP

100

90%

sin2q23=0.40
sin2q23=0.45
sin2q23=0.50
sin2q23=0.55
sin2q23=0.60

-150

-100

6
5
4
3
2
1
0
-50

True

True
NH
[NH]
100

150

10
9
8
7
6
5
4
3
2
1
0

sin2q23=0.40
sin2q23=0.45
sin2q23=0.50
sin2q23=0.55
sin2q23=0.60

90%
1s
-150

-100

-50

0

50

100

dCP

sin q23=0.40
sin2q23=0.45
sin2q23=0.50
sin2q23=0.55
sin2q23=0.60

150

dCP
sin q23=0.40
sin2q23=0.45
sin2q23=0.50
sin2q23=0.55
sin2q23=0.60

2

2

D c2

100

10
9
8
7
6
5
4
3
2
1
0

D c2

D c2

sin2q23=0.40
sin2q23=0.45
sin2q23=0.50
sin2q23=0.55
sin2q23=0.60

D c2

error
7.8 ×1021 POT; W ithout systematic7.8×1021 POT; W ith 2012 systematic errors
Noν sys.
err.POT
w/ 2012ne, ~13%50%+ 100%
50% POTνPOT ν̄ν50% sys.
POTerr.
ν + (~10%
50% POTν̄ nm)

90%

90%

1s

1s

-150 0 -10050 -50100 0 150 50

dCP

True
True
IH
[IH]
100

150

dCP

10
9
8
7
6
5
4
3
2
1
0

90%
1s
-150

-100

-50

0

50

100

150

dCP

2
2
2
−3
×10− 3 2eV= 2.4Assuming
g true: sin2 2θ13 = 0.1, ∆ m 32
true:
sin2Dm2θ213 =2.4×10= 0.1, ∆ -3meVeV 2
32 2= 2.4 ×10
Assuming
true:
sin
2q
=0.1,
13
32
2
0.005
=
)
2θ
δ(sin
θ13 constrained by2
13by δ(sin2 2θ13 ) = 0.005/ 22θ)
13= constrained
q constrained by d(sin 142q
0.005
13

13

15 / 22

T2K + NOnA Sensitivity for Resolving sindCP≠0
Both T2K / NOnA : full POT ( POT fraction : 50% n + 50% anti-n)Plots are for normal hierarchy
Red: T2K alone, Blue: NOnA alone, Black: T2K + NOnA
solid(dash): w/o (w/) systematics

T2K

NOnA
Region where sind=0
can be excluded by 90% C.L.

Sensitivity to resolve sind=0

Assuming 5% (10%) normalization uncertainty on signal (background)
Assuming true: sin22q13=0.1, Dm232=2.4×10-3 eV2, q13 constrained by d(sin22q13) = 0.005

T2K + NOnA Sensitivity to Mass Hierarchy
Both T2K / NOnA : full POT ( POT fraction : 50% n + 50% anti-n)Plots are for normal hierarchy
Red: T2K alone, Blue: NOnA alone, Black: T2K + NOnA
solid(dash): w/o (w/) systematics

solid(dash):w/o (w/) syst.

NOnA

Region where MH can be
distinguished by 90% C.L.

Sensitivity to resolve MH

Assuming true: sin22q13=0.1, Dm232=2.4×10-3 eV2, q13 constrained by d(sin22q13) = 0.005

Summary
nm disappearance results– We have measured q23 with the world-leading precision– New result favors maximal mixing

ne appearance results– We have constrain the CP violating phase dCP by combining
our ne appearance results with the reactor measurements– Best fit is found at very interesting point, dCP ~ -p/2.
If it is true, severe competition with NOnA.
Important to increase statistics ASAP.

Future sensitivity study– May be possible to constrain dCP– Combined analysis with NOnA enhances
the sensitivities to dCP and the mass hierarchy– Higher power at design value ( 750 kW ) beam operation
is anticipated.