T2K Experiment- Neutrino beam commissioning Ken Sakashita(KEK) for T2K collaboration
Feb/22/2010, 「フレーバーの物理の新展開」研究会2010
1. Introduction of T2K experiment- Motivation, Features and Sensitivity
2. Beam Commissioning [Apr ’09 ~ ]- T2K ν beam-line operation started
3. Status of hadron production measurement
4. Future prospects
5. Summary1Motivation

Current-i! Stat
Ue3 = s13e

Next step in ν Oscillation Experiment• discover a finite θ

13

T2K: νe appearance→ important role for future neutrino experiments
CPV in lepton sector•• mass hierarchy

hint on Baryon# asymmetry of Universe• precise measurement|Ue3|2
Sterile ! depending on the validity of
the LSND result

Is θ23 maximal ?

T2K: νμ disappearance0νββdecay exp.

Dirac or Majorana

Tritium β
decay exp.

absolute mass scale

normalinverted?
2

T2K Experiment

Super-Kamiokande

T2K: Tokai-to(2)to(2) Kamioka (~100Long base-line ν oscillation experiment
Super-K•NewT2K(approved in 2
accelerator(~MW),& detector– Construction:20
J-PARC@Tokai ν beam-line– Experiment: 20
Super-K
50ktonOff-axis beam: Narro

P("µ&"e)New electronics installed last summer

O
16
"e

T2K-I
(0.75MW+ SK)
T2K features toenhancethe sensitivity! "µ! "e appearance
as main neutrino detector‣ Super-Kamiokande(SK)– Aim
discover #13
Off-axis method
band νtoμ beam from J-PARC‣ Intense narrow"µ!reconstruction"x disappearance:‣ Neutrino!energy
22# energy
CCQE interactions
dominate– Precise$m23at2,T2K
sinbeam
23
28

3

E (Ge

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)

4

Experimental Setupptarget/Horn

Decay volume!

Muon
detector

Near
Detector

proton0m•

Far Detector(Super-K)!"

on-axis

π→μν

118 m
m
110

280 m

295 kmNear Neutrino Detector

Two

Near Detectors

Muon monitor & on-axis neutrino detectorOO

Off-axis- monitor direction of μ and νμ beam

On-a

✓ uncertainty of beam direction to be < 1mrad•

14m

off-axis neutrino detector- measure Eν distribution, flux, flavor contents• Far neutrino detector (Super-Kamiokande)- measure ν beam composition after 295 km

On-axis

M
!
I

Off-a

M

ν beamC

17.5m
September 22nd, 2006

5
NNN2006,
Univers

First beam to S
Super Kamiokande (far detector)•••zSK was stably taking the data during
50 kton water Cherenkov detector (fiducial volume: 22.5 kton)
zSpill timing based on GPS is succes
Kamiokasite.
good e-like(shower ring) / μ-like separation,
δEscale~ 2%•

No fatal delay of the data transfer during
Far
Detector:
SKIII
New electronics & DAQ was installed in summer
2008 & stably running
date is happened.

••

50kt Water Cherenkov detector (Fiducial : 22.5kt)
zOnlinedata selection for T2K is wor
realtime istransfer
of T2K
beam spill (GPS)information
SK reconstruction
done in Apr.
2006.
trip
! Back to 40% Photo coverage in July, 2006
→ trigger of T2K event Round
Ready for T2K !!!
transfer d

T2K trigger = spill timing ± 500μsec~11000 x 20inch PMTs!"ICRR, Univ. of Tokyo (inner detector)
6

!e appearance
search!"#$%&%'%&()*+),-.
Sensitivity

νe appearance

single EM shower"e(0.4% of !" at peak energy)

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

!

0

0

#

0

small opening
angle

#

!" beamk energy)

C3D)E*FG$%#33,-.H5655I)?)@5A)/6B6
7893:36J<-5=.K-5A)$($6)"LL*L>;0!(,(!&8898

0single EM shower-.

%,(*&56*)3!78898!:863*)9'-$0!(,(!&8898!"##$0!(,(!&8898

multi. EM shower(overlap)

sin22!12 = 0.87
13

sin22!23 = 1.0

!
0

"# !

n

as e

ration cut
g efficiency

small opening
angle

#34

nce

!

'
)"
@ 8' x 1021 protons(30GeV)"*'+,- %• signal''! !" # " " $ #$$%& '(") $%& '(') $%&• Backgroundon &targetbeam νe background
π0 background• intrinsic ! in the ! beam/$0!12!" !%&'()*)+)*,
Signal : e- from !e CCQE int.

!

"m223 = 2.4 x 10-3 eV2$"m212 = 7.6 x 10-5 eV2multi. EM shower(overlap)!!!"#$%&'13',")'(!#*"!
.!/0!121&3$!%&!#*)45#*64!7819:;%<&=>!?!"@)!
A1=-!!1!A8!?!"B!
A8!0C/-!!µ ?!"#!

!

!!!
-$!.

!

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

!"
##

$%
&'
()*
+&
+

CHOOZ
excluded3--$!#-$!-;<-5()'#!#!"-.!(&'()*)+)*,)M1C?.5N"O"#> x10 improvement from CHOOZ limit7(/50MeV/22.5kt/5yr)

Stat. only (OA2.5
100
ALLCHAN°)T2K goal
0.01

2]< 1 x 10-48040--68%CL20--90%CL--99%CL
0
0

0.5

1

100

no-osc.

200
100

(MC)

non-QE bkg.

0

1

1.5
2
rec
Eν (GeV)rec(1.0, 2.3x10 )1223.

ALLCHAN

1310.

100

sin2(2!23)= 1"m223 = 2.7x10-3

20040

0.5

@ 8 x 1021 protons(30GeV)
1
1.5
2
on target
Eν (GeV)-3&SKobs(E#)

30060

0.5

0

1.5
2
rec
Eν (GeV)

ALLCHAN&SKpred(E#) 40080

0

40
20

(/50MeV/22.5kt/5yr)

4805.

1344.

60

(1.0, 2.0x10 )300

0ALLCHAN-3

ALLCHAN

400

<10%
0%
0%

ors
(E")

(/50MeV/22.5kt/5yr)

ystematic error

80

Sensitivity

60

νμ disappearance

5%

1636.

(/50MeV/22.5kt/5yr)

3)(/50MeV/22.5kt/5yr)

w/ high statistics

Stat. only (OA2.5°)

50

(MC)

10020
0 0 0
0.5
-1
-0.5

0

1.5
0 1 0.5
12
rectruerec (GeV)Eν -EνEν
(GeV)
-3

0

0.5

1

1.5
2
rec
Eν (GeV)(1.0, 3.0x10-3)(1.0, 2.7x10 )

図 3.4: 1Rµ 事象の再構成されたエネルギー分布 (左図) とエネルギー分解能 (右図)。とも16にニュートリノ振動がない場合の分布で、図中の網掛け部分は non-QE 反応からの寄与を
図 3.5: 様々な ∆m2 の値に対して SK で期待される 1Rµ 事象のエネルギー分布。真の ∆m2示している。

∆m =2.0, 2.3, 2.7, 3.0×10 eV の場合について示した。ただし、混--68%CLδ(sin22θの値がそれぞれ、
23) ~ 1%合角については sin 2θ = 1.0。図中の網掛け部分は non-QE 反応からの寄与を示している。
--90%CL
3.2.2 ニュートリノエネルギーの再構成δ(Δm223) < 1 x 10-4 eV2--99%CL
2

−3

2

2

”single ring muon-like” (1Rµ) 事象のニュートリノエネルギーは、ニュートリノ反応でいては sin2 2θ = 1.0 を仮定している。
生成したミューオンの運動量から CC-QE 反応を仮定して式 (2.5) により再構成される。す図 3.5 から、振動がない場合のエネルギー分布 (図 3.4) に比べ、分布の形が大きく歪む
なわち、
2mn Eµ − 様子がうかがえる。また、
mµ /2 − (m2n − m2p )/2
non-QE 反応からの寄与の部分も ∆m2 の値によって形が変わEνrec =
(3.1)
mn るが、それは表− Eµ + pµ cos θµ 3.4 からも分かるように、non-QE 反応の大部分は CC 反応であり振動パラメータに依存するためである。
ここで、Eµ , pµ , mµ はニュートリノ反応によって生成されたミューオンのエネルギー、運動量、質量、θµ はニュートリノとミューオンの運動方向のなす角、mn , mp はそれぞれ中性子、陽子の質量である。ただし、始状態の中性子は静止していると仮定している。
図 3.4 にニュートリノ振動がない場合の3.4
1Rµ 事象の再構成されたエネルギー分布とエネ
統計誤差のみでの振動パラメータの決定精度
ルギー分解能を示した。

8

T2K beam-line

9T2K Neutrino Beam-line
Horn1 Installation!
construction was almost completed in April/2009[2004-2009, 5years]!"#$%&&%'(")#*++,,-,-)(").%"/)01#$/)

Horn
Horn-1

Muon Monitor

!+

to SK

3 Horns w/ 320kA
in design current+!

TargetGraphite, Φ26 x
900 mm longproton

"!

30GeV
MR

Near detector(to be readyby end of this year )NearDetector
Super-Conducting
DecayVolume/Dump Super-Conducting
Magnets
Combined function Magnets
110m length
10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

111

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
12

T2K beam-line この1年2009 Feb~March
April
May

June
~ November

preparation for first beamFirst neutrino beam
Beam commissioning
Horn 2,3 installation
Helium filled in TargetStation/DecayVolume
Horn operation test in He environment

NovemberBeam commissioning

DecemberBeam commissioning

2010 January

Beam commissioning13

First T2K neutrino beam produced on April/23/2009
Muon monitor signal
at 1st shot after SC turned onion chambersilicon detector
scintillator(for commissioning)

proton profile just in front of the target
after 9 shots beam tuning(fluorescence plate)x = -1.4 mm
y = -0.8 mm
14

T2K beam-line この1年2009 Feb~March
April
May

June
~ November

preparation for first beamFirst neutrino beam
Beam commissioning
Horn 2,3 installation
Helium filled in TargetStation/DecayVolume
Horn operation test in He environment

NovemberBeam commissioning

DecemberBeam commissioning

2010 January

Beam commissioning
15

Beam commissioning• Goal• establish operation of beam monitors (at high beam intensity)• tune beam orbit and beam position and size on the target• tune neutrino beam direction by Mumon & INGRID
periodtotal # ofprotons

beam condition
6 sec repetition

highlights
check all the components work

2009.4~5 4~8e11 ppp (single/two bunch)

only Horn1~ 2 x 1014 as expected2009.11

3.52 repetition~20kW (a few shots)no Horn~ 8 x 1014 First neutrino event in INGRID

2009.12~20kW (<30min)~50kW (a few shots)

Horn 1,2,3

3 Horns operation~ 4 x 1016 high power trial
First neutrino event in Off-axis

2010.01~20kW(continuous)

Horn 1,2,3~ 5 x 1017 high power continuous run

beam monitor studies

16

!"#$%"&'"()(*+,%$("+#)

中心軌道からのズレ(m)Beam orbit

各点はビームモニターの測定結果

Horizontal: r1mm
ビーム入射方向

Before tuning

targetAfter tuning
ターゲット

取り出し点

中心軌道からのズレ(m)OTR X=-0.5mm

Vertical: r2mm
MR V-bump off

MR V-bump on
ビーム入射方向OTR y=-0.1mm

targetビームライン上の位置(m)17

Beam size
ビームサイズ Y (m) ビームサイズ X (m)!"#$%&'"()*+,)-.+#,/"+
Beam size manipulation at target demonstrated
ビーム入射方向!"#$%&'"()*+,)-.+#,/"+

ビーム入射方向ビームライン上の位置(m)Vx = 2.3mm, Vy = 2.0mm ÅÆ Vx = 3.2mm, Vy = 3.4mm (SSEM19)
Beam size @ 50kW trial : Vx = 6.0mm, Vy = 6.5mm (intentionally enlarged)
Design:Vy = V4.3mm= 2.3mm,
V = 2.0mm ÅÆ VVx ==4.3mm,
3.2mm,= 3.4mm (SSEM19)

Vx
y
x
y
Beam size @ 50kW trial : Vx = 6.0mm, Vy = 6.5mm (intentionally enlarged)18

Beam monitor works well=>8.?>@09A7'8>B.AC7>B7D9.@E.@FGC$089H0C/7IC95
at high intensity!&!&#";$!%!#'''()6*+,!"#$!%'''()#%*+,
Beam
profile (SSEM)&"3$!% '''()3%*-./01(!!,2:";5-./01(1!,2&"355-./01(1!,23"455=>8.?>@09A7'8>B.AC7>B7D9.@E.@FGC$089H0C/7IC95("$)&"%#7557589("$)%"3#7557589/,("$)!"6#7557589/,• Observed emittance increases at highintensity as expected•#";$!%!#'''()6*+,-./01(1!,2&"355("$)%"3#7557589/,
Low enough beam loss for high intensity!"#$!%!&'''()#%*+,-./01(1!,23"455("$)!"6#7557589/,&"3$!%!&'''()3%*+-./01(!!,2:";55("$)&"%#7557589/

beam=>8.?>@09A7'8>B.AC7>B7D9.@E.@FGC$089H0C/7IC95!#&"3$!%!&'''()3%*+,'''()6*+,!"#$!%!&'''()#%*+,
putting
material• loss size was studied by#";$!%-./01(!!,2:";55-./01(1!,23"455JC80.H9A7'8>B.AC7>B7D9.@E.@FGC$089H0C/7IC95(other beam monitor) in("-./01(1!,2&"355
thebeam(" )&"%#7557589/,)%"3#7557589/,(" )!"6#7557589/,$$$#";$!%!#'''()6*+,-./01(1!,2!"#55("$)%";#7557589/,• OTR signal (Ti target) was observed!"#$!%!&'''()#%*+,-./01(1!,2#"%55("<)!";#7557589/,&"3$!%!&'''()3-./01(!!,2#"4("<)&"3#75575#";$!%!#'''()6*+,
w/ SSEM -./01(1!,2!"#55("$)%";#7557589/,

Beam Loss@50kW!"#$%&'('#$$%&$'

w/o SSEM!
except for Arc section!"#$!%!&'''()#%*+,-./01(1!,2#"%55("<)!";#7557589/,&"3$!%!&'''()3%-./01(!!,2#"45("<)&"3#755758!

OTR: Ti target @50kW
JC80.H9A7'8>B.AC7>B7D9.@E.@FGC$089H0C/7IC95)#$$%&$'!##";$!% '''()6*+,~2.5W(SSEM-in)-./01(1!,2!"#55→ <(" 0.5W(SSEM-out))%";#7557589/,++%,-./(#$$%&$'

0123-456-++%,$"#$$%&$'!

!"#$!%!&'''()#%*+,-./01(1!,2#"%55("<)!";#7557589/,

Y (pixel)

ビームロス量JC80.H9A7'8>B.AC7>B7D9.@E.@FGC$089H0C/7IC95*#$$%&$'!

&"3$!%!&'''()3%*+,-./01(!!,2#"455("<)&"3#7557589/,$#$$%&$$

ビーム上流

ビーム下流

!"#$$%&$'!

Fluorescence plate!

X (pixel)

Fluorescence plate

19

!"#$%&'()*+",-.
Muon monitor measurement
run280089, event33 : 4.5 x 1012 ppb , 1bunch, 3horns @320kA
Muon monitor [4.5 x 1012 ppb, 1bunch 3Horns@320kA]

Muon profile measured by
Silicon and Chamber detector
measurement is
consistent each other!"#$%&"'(longitudinal
position.
Si & IC consistent. Data before the final beam tuning.

Horn focusing effectobserved by Muon monitor

1551 pC
467 pC219 pC

82 cm
95 cm
109 cm38.5 pC
13.2 pC
6.3 pC

90 cm
103 cm
125 cm20

Stability of beam
20kW continuous operation~Muonの強度• Beam position from MR is stable(<0.2mm day by day)
• Stability of Muon yield <1%→Good beam stability
Stability
of
beam
angle
(by
Mumon)
is~0.03mrad•• Beam loss is small and stable during the run

including stability ofbeam + horn field + detector

ビームshot数（時間軸に相当）
21

Achievements in beam commissioning
basic functionality of beam monitors and beam-line equipment(e.g. Super-conduction combined magnet) was confirmed
Spill information successfully transfers to SK w/o any troubles
high intensity trial succeeded (~50kW x ~10shots)- beam monitor/equipment works fine & small beam loss
beam direction was tuned
perform continuous operation w/ 20kW

- confirm good enough beam stability
T2K beam-line is basically ready for physics run
22

Hadron production measurement23

Hadron production measurementptarget/Horn!+

Decay volume

+

+

!"

Far Detector(Super-K)

Near
Detector

proton! #" !"
118
110 m

0.43EπEν =(1 + γπ2 θν2 )280 m

Eν distribution is different between ND and SK• ストラテジーや Kの生成分布 (運動量-生成角度分布) SK(E!)•☆π前置検出器(ND)の測定量を外挿してNと geometrical acceptance に依存を求める

distribution from 30GeV proton + C interaction
しかし、NDとSKでﬂuxが異なる

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

1.2

ratio

ND(E )N!
ND" (E!) = ND
ND(E )
#
(E
)
x
$
so
far,
no
measurementofπ,Kproduction!
!
•

295 kmFar-to-Near ratio : !µ

Flux(a.u.)
arbitraryunit

0m

on-axisNSK(E!) = "SK(E!) x #SK(E!) x $SK(E!)
hadron production is a large uncertainty in T2K! "の親粒子の生成分布から"SK(E!)と"ND(E!)のRF/N(E!) =1
0.8"SK(E!)"ND(E!)

0.6
0.4
0.2

→ measurehadron productionNDSK00

関係を求める：例えば # (E") = RF/N(E") x # (E")

this ratio is different forother hadron production model
0.5

1

1.5
F/N ratio

2

2.5

3

E! (GeV)24• measure hadron production in CERN NA61 experiment(data was taken in 2007, 2009)• comparison data with T2K beam-MC• GEANT FLUKA (old FLUKA) used in MC
preliminary results of π+ production (31GeV proton + 2cm Carbon target)
h_pp1_pip

PP of pi+ (0-60mrad)

10

10
8

data

6
4
2

0

0

2

4

6

8

PP of pi+ (0-60mrad)

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

mb/GeV/c

MC0-60mrad00

PP of pi+ (120-180mrad)

2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2

10

12

14

16

18

20

h_comp_pp1

MC120-180mrad

2

4

6

6

8

8

10

10

10

12

12

14

14

data

16

16

18

18

20

20

h_comp_pp3
Entries
Mean
RMS

data

15
10
5
0

0

2

4

6

8

PP of pi+ (60-120mrad)

10

10

12

16

18

h_comp_pp2

momentum (GeV/c)

742211
1.595
1.163

data

0

2

4

6

8

10

12

14

16

18

20

0

2

4

6

8

10

10

12

14

16

18

20

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

2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0

100
5.863
2.61

MC

180-240mrad

5
0

20

h_pp4_pip

0.6
20
0.4
15
0.2

0

20

Entries
Mean
RMS

30

10
0

14

Entries
Mean
RMS

2
1.8
PP of pi+ 1.6(180-240mrad)
985218
2.157
1.4
35
1.558
1.2
30
1
25
0.8

momentum (GeV/c)

MC60-120mrad

20

0

20

1372412
3.378
2.328

25

100
5.277
2.668

h_pp3_pip

4

Entries
Mean
RMS

momentum (GeV/c)
Entries
Mean
RMS

2

30

20

Entries
Mean
RMS

20

0

10

mb/GeV/c

mb/GeV/c12h_pp2_pip

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

mb/GeV/c

Entries
Mean
RMS

20

h_comp_pp4
Entries
Mean
RMS

momentum (GeV/c)→ 物理解析に向けた準備も進行中
25

100
3.53
1.332

Prospects & Schedule
We aim for better sensitivity than the current limit by CHOOZ using data ofphysics run of 2010 as a first stepCL θ!13!"#$%&'&(&')!*+,-.
Sensitivity (δ=0)
1,2!34!
• assigned beam time from Feb/23 to June 2010 / 90%• physics run will start as soon as possible
CHOOZ
/0

")%'#A?'&B!5::8:!C:?B'&8$%&$=!=!!/0!%#$%&'&(&')

excluded/,2!%)%!#::8:!//,

Next : We hope to discover νe appearancewith 1-2 x 107 MW*sec in a few years• sin22θ13 = 0.05 (3σ discovery @ 1MW*107sec)+2!%)%!#::8:=,2!%)%!#::8:/,!=0.03 (3σ discovery @ 2MW*107sec)

Final results with 3.75 x 107 MW*sec(8x1021 p.o.t.)/,!0 !//,/
5678%9:#;<==>+-'!6!/)#?:@
7 MW*s
7 MW*sx x0.75
0.75x x1010

0.1 x 107MW*s

T2K goal26

Summary• T2K neutrino oscillation experiment, our goals are• discover νμ → νe appearance (a finite θ13)

one order of magnitude sensitivity improvementfrom the current limit• νμ disappearance for precise measurement of sin22θ23, Δm223• T2K neutrino beam-line operation starts• confirmed good enough stability of beam (δbeam angle << 1mrad)• beam commissioning almost finish → move to physics data taking• Aim for better sensitivity than the current limit by CHOOZ
as a first step

27

backup28

=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
events300

200

non-QE
events

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)

µ)

E!

!
0

0.5

1

"

100

(p",#")
13
1.5 p 2$rec (GeV)
Eν

0

-1

-0.5

0

0.5
1
Eν -Eν (GeV)
rec

true

29
図 3.4: 1Rµ 事象の再構成されたエネルギー分布 (左図) とエネルギー分解能 (右図)。とも• ニュートリノビーム方向の安定性精度• SKでのE peakを<2%で抑える← Δm の系統誤差10• ビーム方向を±1mrad以下で抑える第 2 章 ニュート リノビームモニター
2νSK Eν peakの変化
peak energy (MeV)

Flux (arb.unit)

SK fluxの変化
1.3
1.2
1.1
1

23

1000
900
800
700
600
500
400

0.9

300
200

0.8

100
0.71.8

2

2.2

2.4

2.6

2.8
3
3.2
Off axis angle (degree)

01.8

2

2.2

2.4

2.6

2.8
3
3.2
Off-axis angle (degree)30

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

2

2

CPV

2

+ 4S12 C13 (C12 C23 + S12 S 23 S13 " 2C12C23 S12 S 23 S13 cos $ ) sin 2 ! 212

2

" 8C13 S13 S 23 (1 " 2S13 )L = 295 km, <Eν> ~0.6GeV
sinΦ21 ~ 0.05

aL
cos ! 32 sin ! 31
4E

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]

�

L
4E

∝L

• 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

31

Stability of beam
20kW continuous operation• Stability of beam timing < 4 nsec during a day• Stability of proton intensity ~3% during a day
proton beam強度の安定性

beam取り出しtimingの安定性

MR condition
was changed

32Hardware upgrade• collimator in the primary beam-line• remote-controllable attenuator module• new Horn power supply• prepare spare target & Horn magnets• establish remote maintenance scenario at TS
collimator
He vessel

Maintenancearea
Apparatus
Spare Target
Spare 1st Horn

2009
12

2

3

4

Production
Production

6
7
8
9
10
11
Horn/Target
remotemaintenance
2010

1

Assembly5

Test@KEK

Shipment

33