Nov. 11th, 2010
@IPMU

T2K and Beyond
T. Nakaya (Kyoto,IPMU)
1OUTLINE
Introduction to T2K
Physics Sensitivity

Experimental Overview
T2K status
Beyond2

1. INTRODUCTION TO T2K

νe

ν1
ν2ντ
νs750kWνµν3
Near Detectors
Pure νµ beam
280m

3

4

BIRTH OF T2K

 The JHF-Kamioka

neutrino project.
hep-ex/0106019


T2Kの物理Citation: 690
5

T2K Strategy
Intense ν beam
J-PARCHigh Quality ν beamT2K

Gigantic ν detector

Off-axis ν beam Super-K(Hyper-K)

6

MISSION OF T2K Discovery of νe appearance !

 A new phenomenon.

 Complete the picture of three generation mixingscheme.
 A window to study CP violation and masshierarchy.
 Precision measurements of neutrino oscillation.
 Confirmation of standard neutrino oscillation
scenario.
=> Precise determination of parameters?
or=> Probe new physics！
7

YOUR INTERESTS IN T2K
My personal guesses:
 When will T2K have the results?
 How is the J-PARC accelerator running?

Is the option of anti-neutrino running?

 Does T2K have the sensitivity to the CP violationand the sign of ∆m2?
 What is the future upgrade (or successor) of T2K?

8νeT2K PHYSICS SENSITIVITYνµ ντOscillation Probabilities when ∆m12 << ∆m23 ≈ ∆m132

 θ23 : νµ disappearance2(2ν3∆m2atm

ν2ν1∆m2sun)

2Pνµ →νx ≈ 1 − cos 4 θ13 ⋅ sin 2 2θ 23 ⋅ sin 2 1.27 ∆m23
L / Eν
~1common θ13: νe appearance
2Pνµ →νe ≈ sin 2 θ 23 ⋅ sin 2 2θ13 ⋅ sin 2 (1.27 ∆m23L / Eν )~0.5 δ : CP violation (T2K-beyond)
22 2P(ν µ → ν e ) − P (ν µ → ν e ) 1.27
∆meV
km13[]L[2θ] =0.1sin 2θ) 12~0.18(sin12ACP =≅⋅⋅ sin δ
2E[GeV] 2θ13=0.01
sin θ13)
P (ν µ → ν e ) + P (ν µ → ν e )~0.58(sin9NOTE
 We are working to update the physics

sensitivity based on the current
experimental condition with datacollected so far. However, they are notready yet. So, I show the sensitivity in
our proposal.
 We plan to have the first physicsresults soon (target: within JFY2010).
10

Measurement of θ23 , ∆m232
Use 1 ring µ-like events(= Quasi-Elastic enhanced sample)

νµ + n → µ + p
νto reconstruct neutrino energy.

θµ-µ(Eµ, pµ)p750kW ×5 years

No oscillation ∆m2= 2.5 x10-3 eV2 ∆m2= 2.0 x10-3 eV2~ OA 2.5 deg. ~non-QE

rec. Eν (GeV)

rec. Eν (GeV)(assuming sin2 2θ23=1.0)

rec. Eν11(GeV)

Ratio of Eν to non-oscillation

OSCILLATION PARAMETER FIT
Input:sin22θ23=1.00∆m2= 2.7 x10-3 eV2

Non-QEsensitivity

12

• 1σ
• 90% CL
• 99% CLT2K-I sensitivity with systematic errorsδ(∆m223) <1×10-4 eV2

13normalization ( 5%)non-QE/QE ratio ( 5%)E scale( 2%)Spectrum shape (20%)
Spectrum width ( 5%)δ(sin22θ23)~0.01

Current knowledge:

δ(sin22θ23)~0.1

True ∆m232 (10-3eV2)True ∆m232 (10-3eV2)θ13 measurement (νe appearance search)
sin22θ23=1and δ=0 are assumed.

Signal:• 1ring e-like event (CC QE sample)
Background:e• beam νe contamination (0.4% of νµ)• mis-reconstructed π0 event
x0.4%νµνeπ014

BACKGROUND SUPPRESSION(∆M2=2.5X10-3EV2,SIN22Θ13=0.1)#events (/22.5kt/5year)

104

νµ BG

103

νe signal

102(40% Efficiency)

νe BG

234

FCFV, Evis. >100MeV
single ringe-like PID
no decay-electron
0.35<Eνrec<0.85GeVcosθνe<0.90
Mπ0<100MeV/c2(π0 fitter)∆L<80(π0 fitter)νe signal
νe+νµ backgrond(νµ backgrond)

101
1

1.
2.
3.
4.
5.
6.
7.
8.

5678

Event Selection

15Eνrec (GeV)90%C.L. sensitivity

Sensitivity versus time

sin22θ13∆m2 (eV2)

Θ13 SENSITIVITY (W/ ∆BGSYS=10%)0.008

10-2x20

δBG=20%δBG=10%δBG= 5%

10-1

CHOOZ
excluded

10-2

10-3
10-3
10-3

10-2

10-1

sin22θ1316

1

T2K-I
10

T2K-II
100YearT2K PHYSICS SENSITIVITY
νe appearance(Strong δ dependence )DCHOOZ
90%

CHOOZ
90%

DCHOOZ90%

sin22θ13~10 times improvement from CHOOZ
17

CHOOZ
90%

CP VIOLATION STUDYν beam is an option(Note: Old study with 2°off-axis)
CC interaction

Fluxνµcross section
difference-15%@peakνµνµSign flip by changeof horn polarityνµ1021POT/yr(1st phase)Wrong sign BG

18

T2K PHYSICS SUMMARY WITH FUTURE OPTIONS
 Probe θ13 by looking for νe appearance.

 Precision measurements of θ23 and ∆m223.

 Search for sterile neutrinos by measuring

the neutral current interactions.
 Look for the difference of between νoscillation and ν.
 CP violation (δ in the MNS matrix or
new interactions)193. EXPERIMENTAL OVERVIEW
 Accelerator/Neutrino Beams
 Near Detectors Far Detectors
Intense beamprotons

NA61π, π, π, π, ΚΦν(E)High Resolution
Near detector

Gigantic
Far detector

ν, ν, ν, νσσ
20

T2K (construction: 2004~2010)
Accelerator

J-PARC MR
750kW (design)New

Neutrino Beam

2.5 degree off-axis
Epeak~700MeVNew

Near Detector

Fine-Segmented multi-type detectors w/magnetic field
New(w/ water target)

Far Detector

Water Cherenkov
50ktons (22.5 kt fiducial)
295km away

Near/Far
extrapolation

Hadron production is measured by CERN
New
NA6121

J-PARC Facility(KEK/JAEA）
South to NorthNeutrino Beams(to Kamioka)

Construction
JFY2001~2008
Design Intensity
750kW•J-PARC starts operation toward the world highest
intensity proton accelerator.
• The high power beam could produce the intense
neutrino beam. Bird’s eye photo in January of 2008

OFF-AXIS Ν BEAM CONFIGURATION Quasi Monochromatic Beam

Super-K.
Target Horns

Decay Pipe

Osc. Prob.＠∆m2=3x10-3eV2

θ=2.5゜νµ flux

• The ν beam energy is tuned at
the oscillation maximum.
• Higher signal yield.
• Less background fromhigh energy neutrinos.

OA0°
OA2°
OA2.5°OA3°23

T2K NEUTRINO PRODUCTION MODEνµ flux at SK

K / π = 0.052 @SK= 0.047 @ND

νe flux at SK

K+ / KL / µ+ = 32% / 14% / 54% @SK
24= 29% / 13% / 59% @ND

PRIMARY BEAM-LINE
Assumed Beam Loss
750W@Prep.
250W@FF.
(1W/m @ ARC)

Preparation Section

ARC Section

Final Focusing Section

Beam-line tunnel was completed in December 2006
 Installation finished in 200925

TARGET STATION AND HORNS
320kA current for the horn system

Support Module
Concrete Block
Shield inside

Beam Window
With pillow seal

Iron Block
Shield inside
Remotecoupling
Huge
He vessels

BaffleTarget

1st horn

26

3rd Horn

ND280T2K NEAR DETECTORS(Near Neutrino Detectors)

27

Neutrino Beam Monitor

ND280 OFF-AXIS
B=0.2T
Magnet Coils

 Volume:

3.5×3.5×7.0m3
 P0D: π0 Detector
 FGD+TPC:
Charged Particle
tracking
 EM calorimeter Side-Muon-Range
Detector
28

NEUTRINO BEAM SPECTRUM AT SK AND
ND280

2010/1
1/11

OFF-AXIS DETECTOR
 Measure νµ flux: <5% Measure νµ energy scale: <2%

 Measure intrinsic νe content of beam: <10% Measure non-CCQE backgrounds for both νµ disappearanceand νe appearance: <10%
 Magnetic field, fine segmentation, excellent tracking
 Major international contributions
 High complexity and non-trivial integration

30

FAR DETECTOR: SUPER-KAMIOKANDE IV

31

T2K CONSTRUCTION JUST FINISHED

The last Electron
Calorimeter was justinstalled in October 2010.

32

T2K Status

33

T2K PHYSICS RUN BEGINS IN 2010.
~100kW~50kW(3.28×1019 for physics)
 Continuous run @ ~50kW level Trial up to 100kW successful.
34∝ Beam Power Delivered POT: 3.35×1019OBSERVATION AT SUPER-KAMIOKANDEClass / Beam run

ALLExp.
BG

Fully-Contained (FC)330.0094+ fiducial volume cut+ visible ene. > 30MeV

230.0011(FCFV)First event on Feb.24,2010
 33 FC events, 23 FCFV events observed until end of June Restart from Nov, 2010


Aim to accumulate>150 [kWx107s] by the end of June 201135

FIRST NEUTRINO PHYSICS RUN: PRIMARY

BEAM

Beam orbit is tuned within 2mm from design orbit.
(Critical for controlling beam loss)

Optical transition radiation detector (OTR)
immediately upstream of target:FIRST NEUTRINO PHYSICS RUN: MUON
10JanFeb

MarAprMayJuneMayJune

0Detector intrinsic resolution <1.5mm-10Mu(Si) Total Q/NpProfile center (cm)MONITORRMS/MEAN < 1% (whole period)
JanFebMar

AprMuon monitors:
 Silicon detectors and ionization chambers downstream of hadron
absorber Additional emulsion detectors during commissioning runs
 Direction stable to <1 mrad
 Secondary/primary beam intensity ratio stable to 1%FIRST NEUTRINO EVENTS IN J-PARC
 Nov. 23rd, 2009.

38

FIRST NEUTRINO PHYSICS RUN:ON-AXIS NEUTRINO MONITOR (INGRID)
The first INGRID
neutrino candidate

Neutrino event rate
shows good symmetry:detectors and beamworking well

Beam profile
center is within 1mrad requirement

Neutrino timing
distribution
shows six-bunch
structure ofprimary protonbeamOFF-AXIS DETECTORS
FGD(Canada, Japan)

Elec(UK,Fr)

TPC(Canada/France, Spain, Swiss,Italy, German)
12-FEM board stack-up before
burn-in phase40
P0D(US)

ECAL(UK)

SMRD(Jp,US,Pol,Rus)

40

OFF-AXIS DETECTOR PERFORMANCES

Very small number ofbad channels

Hit Efficiencies >99%For all layers (FGD)

σ ~ 0.6mm

OFF-AXIS DETECTOR MEASUREMENTS

View from Downstream to Upstre

42

A few ND280 neutrino interaction candidates

νµquasi-elastic candidate

single pion candidate

DIS candidate

NEUTRINO INTERACTIONS IN THE T2K
ENERGY (~1GEV) CC quasi elastic (CCQE) ν + n → µ- + p(n in N)

σ/E (10-38cm2/GeV) CC (resonance) single π(CC-1π)
ν + n(p) → µ- + π+ + p(n) (n,p in N)

 DIS (Deep InelasticScattering) ν + N → µ- + mπ+,−,0 + N’

 CC coherent π ν + A → µ- + π+ + A
 NC+ Nuclear Effects

Total (NC+CC)
CC Total
CC quasi-elasticDIS
CC single πNC single π0Eν (GeV)44

Existing Data (poor precision)➩ Measure them more precisely in T2Kσν in this E range interesting:

QE

DIS
1π

MINOS, NuMI
K2K, NOvAMiniBooNE, SciBooNE, T2K
Super-K atmospheric ν45

FIRST NEUTRINO PHYSICS RUN:
SUPER-KAMIOKANDE J-PARC neutrino

events selectedby event timingusing GPS
 SK analysis isvery wellestablished Event selection& cut values
fixed before datacollection forthis runνμ disappearance
analysis

νe appearance search

Timing coincidence w/ beam timing (+TOF)
Fully contained (No OD activity)
Vertex in fiducial volume (>2m from wall)
Evis > 30MeV

Evis > 100MeV

Number of rings =1
μ-like ringe-like ringNo decay electron
Forced 2nd ring: mγγ<105 MeV

Eνrec < 1250MeVFIRST NEUTRINO PHYSICS RUN:
SUPER-KAMIOKANDEFCLEODFC

LE: Low energy triggered eventsOD: Outer detector events
FC: Fully contained events

Event time distribution clearly shows six-bunch beamstructure 33 FC events and 23 are in the Fiducial Volume.
 Expected non-beam background: ~0.001 events
T2K NEUTRINO EVENTSSingle-ring μ-like event

Two-ring event

 Pink diamonds are placed on the wall in the beam

direction starting from the reconstructed vertex.

VERTEX AND DIRECTION(FC, EVIS>30MEV)

Points : Reconstructed event vertex
Arrow : 1st-ring direction

Vertex X vs Y

Vertex R vs Z

Beamdirection

FVID wall

FVID wall

SUPER-K ENERGY SCALE STABILITY
FOR T2K DATA QUALITY ASSUARANCE
Stopping µ (momentum/range)
RMS/MEAN
T2K period : 0.31%(SK-IV all : 0.39%)
Decay-e (momentum)
RMS/MEAN
T2K period : 0.28%(SK-IV all : 0.45%)

Energy scale has been quite stable.

PHYSICS SENSITIVITY OF THIS RUN••

Physics analysis with the 3.23 E19 POT data is underprocessed and will be shown soon.
 Measurements of muon neutrino disappearance22 Sensitive to sin 2θ23 and ∆m 23
 Search for electron neutrino appearance Sensitive to sin22θ13Appealing features
 High quality data with the off-axis beam to studyneutrino oscillations.
 Expect the similar sensitivity as that of K2K51

NEAR TERM IMPROVEMENT The beam power of 2010 Jan.-June run was limited to50kW by the fast-extraction kicker problem.
Fixed during this summer maintenance.
 100kW operation was tested and is successful.
 T2K will start running from the next week.

6 bunch ➝ 8 bunch (33% more protons)
 Acceleration Cycle: 3.64s ➝ 3.2s (14% more protons)➪ 150kW operation is feasible.
52

SHORT TERM GOAL TOWARD 2011150kW.107s

53

Alain Blondel -NUFACT10 -- The T2K
experiment

750kWin 2014

Beyond55

T2K BEYOND

Study Symmetry Violation
between ν and ν

J-PARC Upgrade
KEK Roadmap→1.7MW

Hyper-K

water CBest Optimization

Huge ν detector•Water Cherenkov•Lq. Ar TPC
O(~100k)ton

Liq. Ar

GUTProton Decay 56

Scenario １（Hyper-K @ Kamioka）#water C

CP sensitivity
sin22θ13295km

δ

ＣＰ discovery on δ in the range of
20°～160°and 200°～340°

57v

Scenario 2

νeSpectrum• 100kton Lq. Ar TPC @ 658km• ν beam only
•Sensitivity to the mass hierarchy

sin22θ13=0.03,Normal Hierarchy
δ=90°

δ=180°

δ=270°

δ

CP Measurement Potential

δ=0°

3σ

Okinoshima
658km
0.8deg. Off-axis

58

sin22θ13

NP08, arXiv:0804.2111

Beam νeBackground

YOUR INTERESTS IN T2K
My personal guesses:
 When will T2K have the results?
First results with the similar sensitivity as K2K will come soon.
soon
 In 2011, the sensitivity will be improved to be sin2213~0.05.
 After 2011, the sensitivity will be further improved.
 HowHis
i theth J-PARC
J PARC accelerator
lt running?
i ?

Expect the operation with150kW or higher in 2010-2011.
 Aim the design intensity of 750kW.


Is it the option of anti-neutrino running?
Technically feasible. The physics case should be studied and reviewed
by PAC.

 Does T2K have the sensitivity to the CP violation andm2?



the sign ofThee p
probability
obab ty oof e appea
appearance
a ce has
as tthee ststrongo gC
CP depedependence,de ce, but do2
not have the sensitivity to the sign of m with 300km baseline What is the future upgrade (or successor) of T2K?

J PARC proton beam power upgrade
J-PARC59
 A Huge Far Detector to probe the proton decay and the  CP violation.
60

61