T2K実験
Ken Sakashita(KEK) for T2K collaboration
Dec/17/2010, 平成22年度共同利用研究成果発表会

1. Introduction of T2K experiment- Motivation, Features and Sensitivity
2. Status- T2K physics data taking on-going
3. Future prospects and Summary

Motivation• ν →ν 振動の発見
μea finite θ13

θ13が有限であれば 将来の実験でCPVの測定が可能
CP odd term in P(νμ→νe)sinθ12sinθ13sinθ23sinδ

→ レプトンセクターでのCP violationの発見へ• precise measurement
Is θ23 maximal ?

|Ue3|2

わかっていること!
これまでの実験結果
normalinvertedORMotivation• ν →ν 振動の発見
μea finite θ13 T2K: νe appearance

θ13が有限であれば 将来の実験でCPVの測定が可能
CP odd term in P(νμ→νe)sinθ12sinθ13sinθ23sinδ

→ レプトンセクターでのCP violationの発見へ• precise measurement

Is θ23 maximal ? T2K: νμ disappearance|Ue3|2

わかっていること!
これまでの実験結果
normalinvertedORTokai-to-Kamioka(T2K) 長基線ニュートリノ振動実験

T2K (Tokai to Kamioka) experiment!"#実験の最市川温子 京%&'$()*$!"#$+&

(design intensity 750kW)High intensity QP beam from J-PARC MR to Super-Kamiokande@
295km
国際コラボレーション（~500 members, 61 institutes, 12 countries）



Discoveryof Qe appearanceÆ Determine T
新しいニュートリノ施設＠J-PARC：建設
in 2004-2008, コミッショニング in 200913
Last unknown mixing angle
今年から物理データの収集を開始
 Open possibility to explore CPV in lepton sectorFeatures of T2K experiment
Super-Kamiokande(SK) as main neutrino detector- 50kton water cherenkov detector (22.5kton fiducial volume)- good PID (e/μ) at sub-GeV, δE ~ 2%
scaleHigh intense neutrino beam

- conventional beam with ~MW accelerator- pure ν beam from π/K decays (small ν contamination ~1%)μNarrow energy band νμ beam
Neutrino energy reconstructioneOff-axis method- CCQE interactions dominate at T2K beam energy

Far Detector(Super-K)
target/Hornpproton!
Decay volume!"

Eν (GeV)

Off-axis beam : intense & narrow-band beam
0°
1

2°
3°

#
on-axis

0

0

2

2.5°

5

8

Pπ(GeV)the beam energy depends on the off-axis
angle (beam direction)
set off-axis angle to 2.5°
→ beam energy at oscillation max.

(current Δm223 & L=295km)- ~1.2k CC int./year for SK- small high Eν tail (narrow-band)→ small # of bkg. for CCQE

Important to keep the beam direction stable(monitoring & controlling the beam)Experimental setupptarget/Horn

Decay volume!

Near
Detector

Muon
detector

proton!"on-axisπ→μν0m

Far Detector(Super-K)

110 m
118

280 m

295 kmNear Neutrino Detector• ビームの方向のモニター- ミューオンモニター (spill by spill)- on-axis near detector “INGRID” (day by day)Off-axis

uncertainty of beam direction should by <1mrad
e

μ

On

14m
On-axis• ビームのabs. flux, spectrum, ν /ν の測定、

Tw

Near DetectorsOffν beamν相互作用の測定- off-axis near detector (ND280)

17.5m
September 22nd, 2006

NNN2006, Unive

J-PARC Neutrino beam facility
Horn1 Installation!
(大改造なく) 2MWまでのビーム運転可能← 世界最大の施設!"#$%&&%'(")#*++,,-,-)(").%"/)01#$/)

Muon Monitor

DecayVolume

HornSuper-Conducting Magnets

Si array+ IC array

110m length

神岡へ

μ+

3 Horns w/ 320kA!

+(design)

30GeV
beam
monitorsMR(intensity,
profile,position, loss)νμNear Detector

3(%#345#/)26%/&+>*&5?*<.:/><!"#$%&'()*+,"#-.//0&+#1"#!)2%//)

TargetBeam Dump

TargetStation

Helium cooling
Graphite, Φ26 x-.2'/#7089%2#:%/;
900 mm long!"#$%&'()**%+,-./0)*1234*5''(**
6'*72,8**5''(*9.:-0*;,<0

proton beam
=5

sensitivity @ 8 x 10 protons(30GeV) on target21

ν disappearance!"#$%&'()*+,&-)-#("()%,%.##-)/,

νe appearance!

μ/$0!12!"-.!%&'()*)+)*,MINOS & Super-K preliminary @ Nu10%,(*&56*)3!78898!:863*)9'! 0-))$1,2(-#,%&(+").#,;0!(,(!&8898+(3"()(4,$3,$%+*55-6$3,#-7*#.#,,
sin22!12 = 0.87
sin22!23 = 1.0,,,,,!,8$$4,%(3%*69*"/,"$,"m223 = 2.4 x 10-3 eV2-"#$%&'()*+,&-)-#("()%,"m212 = 7.6 x 10-5 eV2! !"#$%&$'()$*)+,-+&.(! ")+*//0/1!2324(((89($:/(! 56//1(7(432("(42CHOOZ-$0!(,(!&8898

#34

!"#

$

!!!"#

#$0!(,(!&8898

90% c.l. T2K
w/ 3.75 MW!107 s:;0<=,

excluded

!!!
-$!.

-$!#
-$!()'#!#!"-.!(&'()*)+)*,$%&%'()*+,-.+)+/01+#23034#5,(64/*(37#-> x10 improvement from CHOOZ limit

δ(sin22θ23) ~ 1%
δ(Δm223) < 1 x 10-4 eV2!"#

Status of data taking

2009年4月~12月まで断続的にビームコミッショニング→ ビームの理解、検出器の立ち上げ
2010年1月から物理データ収集を開始

First T2K beam event at SK@2010/Feb./24 6:00
GPSを用いたbeam spill timingでトリガー!月!"日 #$%&'()%*+*,)%-./01
.%'2,3(%*+*,)%
4()%'2,35(678*'2,39%!,:%'2,35(678*'2,39%.':%'2,3%5,7,;(678*'2,39%4()%<%!,:%%%%%2,+='2=,)%>=((%?%4..%@*ABC!%%%%>7>*,)D>%?%4"E%@*ABC!"#$%"&"'()&*+*,(,-./"&(01*(23&4
Beam performance
!"#
115kW

50kW

Summer shutdown# of bunch : 6 → 8
rep. rate : 3.64s → 3.2s

6*+3#

!"#$%

!"#$%

&'()*+)

789:;< ;=;90>:85?@ ;=514

78A<9> ;=;90>:8:?@ ;=514&'()*+)

1st run (Jan. toJun.) : ~50kW;9 operation, 3.23 x 1019 protons for physics analysis;9789:;< ;=78A<9> ;=50>:85?@;= 14from Nov.
0>:8:?@: increase;=514
2nd runstartedbeam power up to 115kW

6*+3#

5

Stable beam operation
Stability of proton beam position on the target (Jan-Jun)
陽子ビームのターゲット上での位置が1mm以下のずれでコントロールできている!"#$%&"'()(*+($,-"+.*(-/'"0*1(*+2%*3+/*+4
23*45

23*67

!"#$%&"'()(*+($,-./=8.$1>

Ͳ8.$1>!"#$%&"'()(*+($,-"+.*(-/'"0*1(*+2%*3+/*+4

Stability of beam direction measured by MUMON (Jan-Jun)()(*+($,-./Muon profile center [cm]

23*45

23*67

=8.$1>

23*68: <)(*+($:;)(*+($

23*64=8.$1>

23*68: <)(*+($:;)(*+($

ビームの方向が1mrad以下で安定している
23*66

23*69

01+(

: <)(*+($:;)(*+($

Ͳ8.$1>

Ͳ8.$1>

9

23*64

23*66

23*69

01+(

01+(

on-axis前置検出器(INGRID)の測定

Profile center stability

ν beam方向も安定

Horizontal

Vertical*only stat. error*only stat. error

beam profile (H)*After applying correction factor

Event rate stability (Jan.-Jun.)

Beam center is stable within stat. error during all RUNs

X center = +0.2 ± 1.4(stat.) ± 9.2 cm (sys)Y center = -6.6 ± 1.5(stat.) ± 10.4 cm (sys)
UPDATE TO ALREADY OFFICIAL PLOT

Saturday, December 11, 2010

event rateが安定

99

Off-axis detector
Q measurements
off-axis前置検出器*+*,+-.(!(/*$'0.*/*1+'

FGD cluster timing

安定してデータ収集している

2010前半のデータを解析中!"#$%&'()*+*,+-.(!(/*$'0.*/*1+'!"#$%&'(%#&")*&+,-#&./,01#'&2#"#2&34%5!"#$%&'())%*+',"#%-.%,(/%01(**")&

Energy Loss (keV/cm)

TPC dE/dx official plots

3

32

5

0.4% muons

Event rate are stable
18electrons
pions
protons

4.5
4

16
14

3.5
3

12

FGD

2.5

10

32

small # of bad channels!"#$%&'(%#&")*&+,-#&./,01#'&2#"#2&34%5
P0D

8

1.5

6

1

4

0.5

2
200

400

dE/dx (TPC)

600

800

1000

1200

1400

1600

1800

2000

0

/23/4%.#-'%567
ECAL

p (MeV/c)456(,70'+*.(8/&19

19

Figure 3. Energy loss distribution as a function of the reconstructed momentum for positive
particles.

4. Misidentified muons
The last official plot describes the probability of having a misidentified muon with the TPC
PID. The knowledge of this number is is particularly important for the measurement at ND280
of the νe component in the beam.
To estimate this probability we selected a sample of muons by requiring one and only one re23(
constructed track in each of the three TPCs. We also required that all the three tracks were
negative. The aim of this selection is to provide a clean sample of through going muons.
The distribution of energy loss versus momentum for this sample is shown in figure 4. For
momenta between 200 and 800 M eV /c we have 5 tracks with energy loss compatible with theone of the electrons at 1 σ (0.19% of the total tracks) and 15 tracks compatible at 2 σ (0.72%).

発表(

0.4%

Event rate stability (FGD)/23/4%.#-'%567

20!"#$%&'())%*+',"#%-.%,(/%01(**")&

":3;(<=>>:?>>@*AB,C

6"#'(0#&'(%#&7&8*9:;&#"#$%)&<&989; =>+?1,@)A4('#<$BC&7&8*DEE ":3;(

詳しくは、DEFGH<家城佳、矢野孝臣C発表(<=>>:?>>@*AB,C

6"#'(0#&'(%#&7&8*9:;&#"#$%)&<&989; =>+D

23(

T2K beam events @ Super-Kamiokande
T2K beam eventsは GPSを用いたイベント時間でセレクト!!"##$%"&"'()#*+,)-.

!!"#$%&'()*#+"$",-.*/012*3'(456)

%"&"'#$:'.;:<.1(%"&")#$

relative event timing to the spill timing (Jan-Dec.6)(FC eventsのみ)!!"##$%"&"'()#*+,)-./01%"&"'#$:'.;:<.1(%"&")#$=+>;?/*1

234#5##%678#.9/*

LE: low energy events(Evis>5MeV)OD: Outer層に一定以上のヒットあり
FC: Outer層にヒットなし。Evis>20MeV

J-PARC beam 構造(581nsec間隔 x 8bunch)に一致している2

!"#$%&'()*(+,-'./'0(!/'12

Observed T2K beam events @SK$E&F=.>1?(µ=&>@'(!"#$%&'()*$+($,-.'/0#$
multi-ring μ-like event->1?&'=.>1?(µ=&>@'(single-ring
μ-like event$1$2>?@$5'678$
Pμ =.µ1438
MeV/c"$9'8:;0'<'8)/=(*
2 decayeʼs.µ$1$2342$5'678$
Pμ = 1061
MeV/c
2$9'8:;0'<'8)/=(
1 decaye

A:(0A-('$"323
3µ(4(5675(8'9:;(
D-<<;0E=():+('9$FDEG

5(0';#<='$$$H$$I9-8+:<$&=<-J'$8-)$
H$$&+*+K<'$%$L$?3$5'6$FDED6G$

B$=C$'&'()*
3µ(4(5ABC(8'9:;(??D(0';#<='-
"?

!"#

Super-Kamiokande event selection
SK analysis is well established* >20years experiences w/ Water Cherenkov detector
Event selection & cut value are fixed alreadyQ5R*=KS&*;*$8&D*6*'/($→ Unbiased selection!"#$!µ$%&'())*(#(+,*$(+(-.'&'!"#$!*$())*(#(+,*$'*(#,/$!"#"$%&'("$'")*$'*&+,&-*.#&/#"$%&01!234
35667&'($8."$*)&09(&2:&.'/;"874<*=8*>&"$&?)5'".6&;(65#*&0<*=8*>&@A#&B=(#&+.664
C;"D&@&EFG*<

C;"D&@&HFFG*<
I&(B&="$%&JH

µK6"L*&="$%

*K6"L*&="$%
9(&)*'.7&*6*'8=($M$;N&#.DD&+,&B(='*)KB(5$)&A$)&="$%&O&HFPG*<
C!=*'&O&HAPFG*<

詳しくはHH.QW0中山祥英、亀田純、奥2010前半データの物理解析が進行中
村公宏、上野昂、大林由尚4発表&
TFU&=*)5'/($&(B&-*.#&! &-.'L%=(5$)&*@VVU&=*)5'/($&B=(#&!µ&"$8*=.'/($&

33

analysis strategy
ptarget/Horn!+

Decay volume!"

Far Detector(Super-K)

Near
Detector

proton!+#"+!"NSKobs(Erec)

110 m

280 m

295 km

SKでのν事象数、spectrumの測定値をストラテジーSK(E )☆ 前置検出器(ND)の測定量を外挿してN!
予想値と比較して解析

NSKexp(Erec) = を求める
ND(E )
N
! rec
SK
ND(E
Posc.(E) x Φ "(E)x σ(E)
x
ε(E)
x
M(E,E
)
)
=
!

#ND(E!) x $ND(E!)Φ : Fluxσ : ν int. xsec
ε : efficiency
E: ν true energy
Erec : ν reconst. energy
M(E,Erec) :detector response

Far-to-Near ratio : !µ

Flux(a.u.)
arbitraryunit

0m

on-axisSK flux
ND (off-axis) flux
(normalized by area)

1.2

RF/N(E!) =1

ND(E)を求め、
ND spectrum測定からΦ
しかし、NDとSKでﬂuxが異なる

0.8

beam MCの情報を使って外挿

0.6

NSK(E!) = "SK(E!) x #SK(E!) x $SK(E!)

Beam MC simulation(GFLUKA)"SK(E!)"ND(E!)

0.4
0.2

ΦND(E) = NNDobs(E) / (σ(E)
x ε(E))
SK(E )と"ND(E )の! "の親粒子の生成分布から"
!
!

0
0

関係を求める：例えば #SK(E") = RF/N(E") x #ND(E")
SK= RF /N ×
Npred.
target/Decay volume

ND
Nobs.

σ ND × �

Near
Detector

0.5

1

1.5
F/N ratio

2

2.5

3

E! (GeV)

SK
SK
×
σ
×
�
ND
Far Detector(Super-K)

analysis strategy
ptarget/Horn!+

Decay volume!"

Far Detector(Super-K)

Near
Detector

proton!+#"+!"NSKobs(Erec)

110 m

280 m

295 km

SKでのν事象数、spectrumの測定値をストラテジーSK(E )☆ 前置検出器(ND)の測定量を外挿してN!
予想値と比較して解析

NSKexp(Erec) = を求める
ND(E )
N
! rec
SK
ND(E
Posc.(E) x Φ "(E)x σ(E)
x
ε(E)
x
M(E,E
)
)
=
!

#ND(E!) x $ND(E!)Φ : Fluxσ : ν int. xsec
ε : efficiency
E: ν true energy
Erec : ν reconst. energy
M(E,Erec) :detector response

Far-to-Near ratio : !µ

Flux(a.u.)
arbitraryunit

0m

on-axisSK flux
ND (off-axis) flux
(normalized by area)

1.2

RF/N(E!) =1

ND(E)を求め、
ND spectrum測定からΦ
しかし、NDとSKでﬂuxが異なる

0.8

beam MCの情報を使って外挿

0.6

NSK(E!) = "SK(E!) x #SK(E!) x $SK(E!)

Beam MC simulation(GFLUKA)"SK(E!)"ND(E!)

0.4
0.2

ΦND(E) = NNDobs(E) / (σ(E)
x ε(E))
SK(E )と"ND(E )の! "の親粒子の生成分布から"
!
!

0
0

精度を上げるためには関係を求める：例えば #SK(E") = RF/N(E") x #ND(E")

0.5

1

1.5
F/N ratio2

2.5

E! (GeV)(1) near-to-far extrapolation (beam MCのprediction)ND← Hadron production測定
SK= RF /N ×
Npred.

target/Decay volume

Nobs.

σ ND × �

Near
Detector

3

SK
SK
×
σ
×
�
ND

Far Detector(Super-K)

analysis strategy
ptarget/Horn!+

Decay volume!"

Far Detector(Super-K)

Near
Detector

proton!+#"+!"NSKobs(Erec)

110 m

280 m

295 km

SKでのν事象数、spectrumの測定値をストラテジーSK(E )☆ 前置検出器(ND)の測定量を外挿してN!
予想値と比較して解析

NSKexp(Erec) = を求める
ND(E )
N
! rec
SK
ND(E
Posc.(E) x Φ "(E)x σ(E)
x
ε(E)
x
M(E,E
)
)
=
!

#ND(E!) x $ND(E!)Φ : Fluxσ : ν int. xsec
ε : efficiency
E: ν true energy
Erec : ν reconst. energy
M(E,Erec) :detector response

Beam MC simulation(GFLUKA)
SK flux
ND (off-axis) flux
(normalized by area)

1.2

RF/N(E!) =1

ND(E)を求め、
ND spectrum測定からΦ
しかし、NDとSKでﬂuxが異なる

0.8

beam MCの情報を使って外挿

0.6

NSK(E!) = "SK(E!) x #SK(E!) x $SK(E!)

Far-to-Near ratio : !µ

Flux(a.u.)
arbitraryunit

0m

on-axis"SK(E!)"ND(E!)

0.4
0.2

ΦND(E) = NNDobs(E) / (σ(E)
x ε(E))
SK(E )と"ND(E )の! "の親粒子の生成分布から"
!
!

0
0

精度を上げるためには関係を求める：例えば #SK(E") = RF/N(E") x #ND(E")

0.5

1

1.5
F/N ratio2

2.5

E! (GeV)(1) near-to-far extrapolation (beam MCのprediction)ND← Hadron production測定
SK= RF /N ×
Npred.

(2) neutrino interaction cross section
target/Decay volume

Nobs.

SK
SK
×
σ
×
�
ND

ND × �
←σND280の測定+ これまでの実験結果

Near
Detector3

Far Detector(Super-K)

Hadron production 測定
CERN NA61実験

p + C → π(or K) + X• pilot run in 2007 and high stat. run in 2009
- 30GeV p + C (thin target 4%λI and T2K replica target)
preliminary results of π+ production from thin target(only ʼ07 data, 20% systematic error)
h_pp1_pip

PP of pi+ (0-60mrad)

Entries
Mean
RMS

8

mb/GeV/c

10

6
4
2

0

0

2

2
1.8
PP of pi+ (120-180mrad)
1.6
1.4
30
1.2
251
0.8
20
0.6
0.4
15
0.2
100
0
5

0

0

0

PP of pi+ (120-180mrad)

2
1.8
1.6
1.4
1.2
1
0.8
0.6

4

6

8

10

12

14

16

18

h_pp3_pip

data

2

4

6

8

10

12

14

16

18

20

2

4

6

8

10

12

14

16

18

20

20

h_comp_pp3

15
10
5
0

0

2

0

0

0

PP of pi+ (180-240mrad)
100
4.526
1.955

2
1.8
1.6
1.4
1.2
1
0.8
0.6

4

6

8

10

12

14

16

18

20

Entries
Mean
RMS

2
1.8
PP of pi+ (180-240mrad)
1.6985218
35
2.157
1.4
1.2
30
1
25
0.8
0.6
20
0.4
15
0.2
10
0
0
5

y
20
r
10 na
i momentum (GeV/c)imle
GFLUKA modelr
180-240mrad
dataph_comp_pp2

PP of pi+ (60-120mrad)

momentum (GeV/c)1372412
3.378
2.328

MC modelGFLUKA
data data60-120mrad

100
5.863
2.61

h_pp4_pip

Entries
Mean
RMS

1.558

MC

Entries
Mean
RMS

25

100
5.277
2.668

Entries
Mean
RMS

10

Entries
Mean
RMS

20

20

Entries
Mean
RMS

20

30

y
r
0
20
10 na
momentum (GeV/c)iimle
GFLUKA model
30
r
data
120-180mrad
ph_comp_pp1

PP of pi+ (0-60mrad)

mb/GeV/c

GFLUKAMC modeldata data

0-60mrad10

mb/GeV/c

mb/GeV/c12h_pp2_pip

PP of pi+ (60-120mrad)
15376907.259
4.59

742211
1.595
1.163

MC

data

2

4

6

8

10

12

14

16

18

20

20
2

4

6

8

10

10

12

14

16

18

20
h_comp_pp4

Entries
Mean
RMS

momentum (GeV/c)

implement in beam MC → reduce T2K systematic uncertainty

100
3.53
1.332

Prospects!"#"$!"##%&'(%• 2010 2nd run started in Nov. 18th
- increasing
the beam*4power! )*+,*-.%/012%#3%%(115kW at present)! 56"7%8(9,-+:-%8(%.+*+%8(%;%<--=:%- aim
to accumulate 150kW * 107 sec! >',,-(*%?-+@%A0<-,%5##6%=B%

90% CL θ13 Sensitivity (δ=0)
CHOOZ
excludedby next summer! C8@%D0,%#6"%=B%E%#"F:%?G%H'IG%!"##%! #"J%#:*%,'(%.+*+%: 1MW x 107sec!!!
in a%"%"2"6%
few years• Next step! :-(:8K18*G%*0%:8(#;- sin22θ13 = 0.05

(3σ discovery @ 1MW*107sec)

Final results with 3.75 x 107 MW*sec
21 p.o.t.)$%&%'()*+,-.+)+/01+#23034#5,(64/*(37# (8x1056+7'8433'%)*+''

T2K
goal
!"#$%&'()*+,''-./0'12'!'34/#'

!"#

まとめ
• T2K長基線ニュートリノ振動実験- discovery of νe app. & precise measurement of νμ disapp.
• 物理データ収集を開始- 1st run January - June 2010
beam power ~50kWで運転。ビーム・検出器ともに安定
Observed # of FCFV events : 23
Expect first results by winter 2011 conference- 2nd run Nov. - Summer 2011現在のビームパワー 115kW
Aim for 150kW x 107 sec → sin22θ13 ~ 0.05 (90% C.L.)
査定金額：8万円（T2KSKシフトの旅費の一部として使用)backupFirst beam to S
Super Kamiokande (far detector)

zSKvolume:
was stably
22.5 takingkton) the data durin• 50 kton water Cherenkov detector (fiducial
zSpill timing
based
on GPS is succe
goode-like(showerring)/
μ-likeseparation,
δE
~
2%
•
Kamioka site.
No&fatal
delayof the data transfer durin
New electronics& DAQSKsince
summer 2008
stablyrunning
Detector:-III•Fardate is happened.
information• realtime transfer of T2K beam spill (GPS)zOnline
data selection for T2K is wo
scale

•
•

50kt Water Cherenkov detector (Fiducial : 22.5kt)
SK reconstruction is done in Apr. 2006.
! Back to 40% Photo coverage in July, 2006

→ trigger of T2K event Round tr

Ready for T2K !!!

T2K trigger = spill timing ± 500μsec~11000 x 20inch PMTs!"ICRR, Univ. of Tokyo (inner detector)

transferProton beam monitor
ビーム強度
ターゲット直前のビームプロファイル

ビーム位置

Current Transfomer (CT) Electro Static Monitor (ESM)

Optical Transition Radiation (OTR)!+

protonビームプロファイル

Segmented Secondary
Emission Monitor (SSEM)

ビームロス
30GeV
MR

Beam Loss Monitor (BLM)
monitor namepurposequantityCTintensity

5

ESM

position

21

SSEM

profile

19

BLM

loss

50

OTR

profile at target

1Muon beam monitor
Ion Chamber• measure ν beam direction by

Siliconmuon profile every spill• two independent monitor

covering 1.5m x 1.5m area

• Array of

Ionization chamber• Array of

Silicon PIN photo-diode

to SK

μ+
νμ

!+

=

m N # E µ + p µ cos " µν Energy Reconstruction$E % 60 MeV $E/E ~ 10%QE• ν’s Energy reconstruction is possible for CC Quasi-Elastic
interaction
inelastic(CCQE: νμ(e) + n → μ(e) + p)"(p",#")

Eνrec =

E! (reconstructed)p– E! (true)
ALLCHAN

4805.

400

(MC)

1R!

CCQE
events

300

200

CC1π

100

T2K’s beam energymn − Eµ + pµ cos θµ

400

300

0

mn Eµ − m2µ /2 − (m2n − m2p )/2# of events!
(/50MeV/22.5kt/5yr)

)

E!

!
0

0.5

1

non-QE
events

200

"

100

(p",#")
13
1.5 p 2$rec (GeV)
Eν

0

-1

-0.5

0

0.5
1
Eν -Eν (GeV)
rec

true

θ13 measurement by νe appearance
2

2

!13

2

P(%µ # %e) = 4C13 S13 S 23 sin 2 ! 312

CPC

+ 8C13 S12 S13 S 23 (C12C23 cos $ " S12 S13 S 23 ) cos ! 32 sin ! 31 sin ! 212

" 8C13 C12C23 S12 S13 S 23 sin $ sin ! 32 sin ! 31 sin ! 21
2

2

2

2

2

2

CPV

2

+ 4S12 C13 (C12 C23 + S12 S 23 S13 " 2C12C23 S12 S 23 S13 cos $ ) sin 2 ! 21aL
" 8C13 S13 S 23 (1 " 2S13 ) cos ! 32 sin ! 31
4E
2

2

2

2

L = 295 km, <Eν> ~0.6GeV
sinΦ21 ~ 0.05

matter effect(small in T2K)

δ → −δ, a → −a for P (ν¯µ → ν¯e )
aL
4E

solar

= 7.6 × 10−5 [eV2 ]�ρ[g/cm3 ]

��

E
[GeV]

�

• P(ν →ν )→sin (2θ ) : some ambiguity due to unknown params.
• It is possible to measure CPV by comparing ν and ν
μ

e

2

13

L
4E

∝L

!"#$%&%'%&()*+),!e appearance-.
searchSensitivity of νe appearance '!

#: e from ! CCQE int.
''
' "*'+,)" %• Signal
21
signal ! !" " " #$$%& '( $%& '( $%&#$")') @ 8 x 10 protons(30GeV)
Background• beam ν background&target
π0 backgroundeon• intrinsic ! in the ! beam-esingle EM shower"e(0.4% of !" at peak energy)

/0112
ce
interaction" !
3• NC 1!$%#
3,-.456-.)!
misidentified
as e
•
3
=.
789
:36;<-5>furthere/!
separationcut
QE int.
•& understanding
efficiency?)@5A)/6B6

!

0

0

#

0

small opening
angle

!

!

beam
energy);0!(,(!&8898-$0!(,(!&8898!"#

multi. EM shower(overlap)#$0!(,(!&8898

sin22!12 = 0.87

13!
small opening
angle

sin22!23 = 1.0

!

#34

0

"# !

se

C3D)E*FG$%#33,-.H5655I)?)@5A)/6B6
7893:36J<-5=.K-5A)$($6)"LL*L>%,(*&56*)3!78898!:863*)9'0single EM shower/$0!12!"-.!%&'()*)+)*,"m223 = 2.4 x 10-3 eV2$"m212 = 7.6 x 10-5 eV2ation cutefficiency

multi. EM shower(overlap)!!!"#$%&'',")'(!#*"!
13.!/0!121&3$!%&!#*)45#*64!7819:;%<&=>!?!"@)!
A1=-!!1!A8!?!"B!
A8!0C/-!!µ ?!"#!

!

!

893:36J<-5=.K-5A)$($6)"LL*L

!!!
-$!.

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