J-PARC 3GeV RCSにおける
ビーム調整
～入射部におけるビームロス起源の同定
原田寛之
原子力機構/J-PARCセンター
ビーム物理研究会2010＠理研
2010年11月12日
Linac
[181 MeV at present,
400 MeV with ACS]
J-PARC
(JAEA & KEK)
3 GeV Rapid Cycling
Synchrotron (RCS)
Neutrino Beam Line
to Kamioka
Materials &
Life Science
Facility (MLF)
50 GeV Main Ring
Synchrotron (MR)
[30 GeV in 1st phase]
Hadron
Experimental
Hall
Design parameters of RCS
Circumference
348.333 m
Super periodicity
3
Harmonic number
2
No. of bunch
2
Injection energy
181 MeV
(400 MeV with ACS)
Extraction energy
3 GeV
Repetition rate
25 Hz
Particles per pulse
2.5e13 - 5e13
(8.3e13 for 1 MW)
Output beam power
0.3 - 0.6 MW
(1 MW for upgraded Linac)
Transition gamma
9.14 GeV
Number of dipoles
24
quadrupoles
60 (7 families)
sextupoles
18 (3 families)
steerings
RF cavities
52
12 (11 at present)
Start of the beam commissioning
: October 2007~
RCS Injection System
H-
QFL
3rd foil
2nd foil QDL
MWPM3
MWPM5
MWPM4
x
H+
ISEP1,2
HH0
s
HH0
PB1,2
PB3,4
1st foil
Circulating
beam
SB1
SB2
SB3
SB4
4
Horizontal Painting Injection Process
H-
QFL
MWPM3
3rd foil
2nd foil QDL
MWPM4
1st foil
x
MWPM5
H+
ISEP1,2
H-
s
H0
PB1,2
PB3,4
Circulating beam
x’[mrad]
Circulating beam
H-
SB1
SB2
SB3
SB4
current
0
93
124.1
SB
x[mm]
PB
-4.4
Injection Beam
5
Injection period(500μsec)
time
Horizontal Painting Injection Process
H-
QFL
MWPM3
3rd foil
2nd foil QDL
MWPM4
1st foil
x
MWPM5
H+
ISEP1,2
H-
s
H0
PB1,2
PB3,4
Circulating beam
Circulating beam
x’[mrad]
H-
SB1
SB2
SB3
SB4
current
0
93
124.1
SB
x[mm]
PB
-4.4
Injection Beam
6
Injection period(500μsec)
time
Horizontal Painting Injection Process
H-
QFL
MWPM3
3rd foil
2nd foil QDL
MWPM4
1st foil
x
MWPM5
H+
ISEP1,2
H-
s
H0
PB1,2
PB3,4Circulating beam
Circulating beam
x’[mrad]
H-
SB1
SB2
SB3
SB4
current
0
93
124.1
SB
x[mm]
PB
-4.4
Injection Beam
7
Injection period(500μsec)
time
Vertical Painting Injection process
y‘
y
s
MWPM3
MWPM4
MWPM5
VPB1 VPB2
y
H+
H1st foil
8
Issue of beam loss @ injection section
• Radioactivity at Horizontal plane of HO branch
and BPM
– ~200μSv/h@20kW operation
– ~1-2mSv/h@120kW operation
• Radioactivity at Vertical plane of them
– ~ several 10μSv/h
• No change of loss monitor signal for open/close
of ring collimator
• Ratio of loss signal between 1pass and circulating
mode @ 20kW operation is 17 →equals to
calculation value of averaging foil hit counts
→Must identify the source of beam loss at high
radioactivity points
Issue of beam loss @ RCS Injection section
Ring Collimator
(1) HO branch
~200μSv/h@20kW operation
~1.2mSv/h@120kW operation
H0-Septum2
H0-Q
H0-Septum1
QDL
(2)
(1)
BPM
QFL
Foil
(2) BPM
BPM
~200μSv/h@20kW operation
~2mSv/h@120kW operation
Foil Scattering Distribution
Multiple Coulomb scattering
Multiple Coulomb scattering
Nuclear scattering**
(p, p), (p, n) . . . .
Nuclear scattering
Coulomb & nuclear scattering
Coulomb & nuclear scattering
rad
foil
rad By H. Hotchi
Scattering angle calculation of 106 events by GEANT simulator（Foil : 300μg/cm2）
→Loss particles at H0 branch are 1 or 2 events from particle tracking simulation
→Full simulation with beam core should be avoided in the view point of simulation time
and increasing statics
Scattering angle calculation of 108 events by GEANT simulator (Foil : 300μg/cm 2）
→Select about 104 events of large scattering more than ±3mrad
Horizontal Phase Space
@ 150π Painting Process
1 turn
30 turn
Foil
Foil
Length between
Injection beam position
and Foil edge→12mm
Painting injection only
for horizontal direction
10 turn
40 turn
57 turn
Foil
Foil
20 turn
50 turn
Foil
Foil
Foil
Particles w/ foil hit
Particles w/o foil hit
Particle Tracking (1turn) @150π
3mrad
-3mrad
Total = 2069
Total = 1144
FOIL
QDL
H0 branch
PBH3
PBH4
BPM
QFM
Particle Tracking (57turn) @150π
3mrad
-3mrad
Total = 2293
Total = 1080
FOIL
QDL
H0 branch
PBH3
PBH4
BPM
QFM
Estimation of residual radioactivity @150πpaint
for horizontal
FOIL
QDL
PBH3
PBH4
BPM QFM
Total = 1926
Total = 1115
Assumption :
1W/m = 1mSv/h
1.2kW(47×108)
220144counts (1.59m)
109034counts (0.1m)
105899counts (1.36m)
278μSv/h
35μSv/h
20μSv/h
161141counts (0.2m)
206μSv/h
Estimation of residual radioactivity @150πpaint
for vertical
Total = 310
23@1turn → 18766@circulating
Total = 319
18766events(0.1m)→48μSv/h
FOIL
QDL
H0 branch
PBH3
PBH4
BPM
QFM
Solution of this issue(1)
40mm
15mm
Current Foil Size (110mm x 40mm)
– Average Hit Count @ foil = 8.77
New Foil Size (110mm x 15mm)
– Average Hit Count @ foil = 4.66
1 turn
x’[rad]
Particles w/ foil hit
20 turn
y[m]
Particles w/o foil hit
x[m]
y’[rad]
40 turn
60 turn
80 turn
94 turn
1 turn
x’[rad]
Particles w/ foil hit
20 turn
y[m]
Particles w/o foil hit
x[m]
y’[rad]
40 turn
60 turn
80 turn
94 turn
Solution of this issue(2)
H0-Septum1
Install the new collimator and
shield at H0 branch duct for
localization of this beam loss
H0 branch duct
QDL
Example of localization
Total = 1965
Total = 1096
FOIL
H0 branch
BPM
Example of localization
Collimator
Total = 1965
Total = 1306
FOIL
H0 branch
BPM
Summary
• The source of beam loss for injection section is
identified as the rare events of large-scattering
by the foil hits.
• As the solution of this issue, foil size is smaller
and beam loss is localized at new collimator
system.
Decay Curve of redial radioactivity
1/3mode、ACmode(Foil:260μg/cm2)
1/3mode, 560nsec, 1bunch
0.255
1/3mode, 280nsec, 2bunch
0.267
ACmode, 280nsec, 2bunch
4.372
(~17 times)
By K.Satou & H. Harada
Estimation of Loss Particle
1ターンで入射された粒子数を108として考える。周回ごとに粒子数は増加し、100μs
入射では47ターン入射されるので、トータルの粒子数は47× 108である。
現在、フォイルに当たった粒子を108として大角度のイベント104を飛ばしているため、
各ターンごとに規格化してやる必要がある。
規格化したロス数 = トラッキングでのロス数 × ( ヒットした数 ÷ 全体数 ) × 入射数
(例) 1ターン目
100
=
100
× ( 30000
÷ 30000 ) ×
1
=
100
× ( 30000
÷ 30000 ) ×
2
=
100
× ( 15000
÷ 30000 ) ×
20
=
100
× ( 10000
÷ 30000 ) ×
47
(例) 2ターン目
200
(例) 20ターン目
1000
(例) 57ターン目
1566
Estimation of Loss Particle
ペイン
ト軌道
平均
ロス数
ヒット数 (1/3)
@分岐部
ロス数
(周回)
@分岐部
比率
ロス数 ロス数
（1/3vs周回） (1/3)
(周回)
@BPM @BPM
@分岐部
比率
(1/3対周回)
@BPM
100π
22.9
7050
158924
22.5
10058
224060
22.3
150π
17.4
6439
109034
16.9
9635
161141
16.7
200π
14.2
5828
80559
12.9
9494
122879
12.9
47×108粒子に対するロス粒子数（入射パルス回数：47回、周回数：57回）
第2章6節
大電流ビームの空間電荷効果
ビーム出力100kW時、 Simpsonsのシュミ
レーションによるベータトロン振動数の広がり
ビームの空間電荷力によって発散力
を生じ、粒子は電磁石による外部収束
力を弱く感じる。
(6.40, 6.42)
Δν ～ －0.4
ベータトロン振動数の広がりを生じる。
νy = 6
共鳴線に抵触し、大きなビームロスを
生じる。
νx = 6
垂直方向のベータトロン振動数 νy
ビーム出力を増強する。
Laslettのチューンスプレッドの
nt rp
1
式
  
水平方向のベータトロン振動数 νx
１次共鳴線
２次共鳴線
2 2 3 B f
nt ：全電流、Bf:バンチングファクター
rp ：陽子の古典半径、ε：エミッタンス
β,γ：ローレンツファクター
27
第2章6節
空間電荷力の緩和
～ペインティング入射
x‘
入射ビーム

x
入射軌道や周回軌道を時間的に変
化させつつ、ビーム入射を行い、実
空間上に一様にビームを広がらせる。
入射ビーム
電荷密度を小さくし、空間電荷力を緩
和させる。
 
y‘
ペインティング入射
入射ビーム

Δν ～ －0.4 → －0.1
y
入射ビーム
  /
ε: 周回ビームエミッタンス、β,γ: リングのTwiss parameter
28
Correction of Ring Optics
Tune measured:(6.68, 6.25),
Tune set:(6.64, 6.25)
Dispersions estimated by looking
at a rf-frequency dependence
of the closed orbit
Beta estimated from a response
of the closed orbit for
a dipole kick (STM)
Curves：Design value, Dots：Measured values, Solids：Reconstructed value
ηx, ηy[m]
βx, βy[m]
1/3 ring (straight＋arc)
s[m]
We could
makeoptics
the optics
to thewas
design
curves well
The
measured
(tune,almost
beta, fitted
dispersion)
reasonably
29
with no iteration.
reconstructed
in our accelerator model.
Control of Ring Optics
(νx,νy)=(6.38,6.45)
on 2008/05/26
(νx,νy)=(6.40,6.42)
on 2009/11/02
We can easily control the ring optics (betatron tunes and
beta amplitude functions) with good accuracy!!
Measurement of Response Matrix for frequency
domain and Identification of Injection Phase Space
xn  x0 cos2n x    x sin2n x  x0'  x sin2n x 
x0 : injection position, x0’ : injection derivative, νx: betatron tune,
αx, βx: twiss parameter @ beam monitor, n : number of turns
Fourier Transform
Obtain the real and imaginary part of betatron oscillation component, which have
outputs by a response matrix for injection position and derivative
ReX  x 
 x0 
ImX    R x  x ' 
x 

 0
A12   x0 
A
  11
x' 
A
A
22   0 
 21
x   A
  0'    11
 x0   A21
A12  ReX  x 
A22   ImX  x 
1
31
Measurement of response matrix
ReX  x 
ImX  x 
Re X  x   A11
 ImX     A
x 
 21

A12   x 0 
A22   x 0' 
A11
A12
A21
A22
x 0
x0 '
32
Correction of the injection mismatching
Injection beam
Closed orbit
Injection bump
x at the 1st foil of injection & closed orbits :
adjusted by the shift bump magnet
x'at the 1st foil of the injection orbit :
adjusted by the injection septum magnets
Mountain plot of the beam profile measured by IPM
for 1-intermediate pulse injection
Horizontal profile
Corrected !!
Adjusted so as to minimize the betatron oscillation
Correction of the injection mismatching
(y,y’) at the 1st foil of the injection orbit:
adjusted by injection steering magnets
Mountain plot of the beam profile measured by IPM
for 1-intermediate pulse injection
Vertical profile
Corrected !!
Adjusted so as to minimize the betatron oscillation
Footprint of (x, x’) over
the painting injection process
Single-short pulse injection (25 mA peak, 560 ns long)
600ms
SB
PBH
500ms
t5
X’(rad)
t0
○ 1-pass BPM 1101-1102
△ PB magnet off at t5
□ MWPM3-4
t0
100 
⇒~110
t5
150 
⇒~163
X(m)
200 
⇒~220
Footprint of (y, y’) over
the painting injection process
Single-short pulse injection (25 mA peak , 560 ns long)
○ 1-pass BPM 1101-1102
□ MWPM3-4
600ms
SB
500ms
t0
Y’(rad)
PBV
t5
(Correlate painting)
100 
Y(m)
Acceptance Simulation
30mrad
-30mrad
FOIL
QDL
H0 branch
PBH3
PBH4
BPM
QFM
Result of Acceptance Simulation
Foil Edge
Loss up to branch
7mm
±30mrad
Loss up to BPM
Survive through the
Collimator
Loss at BPM
Loss up to BPM
Loss up to branch
Acceptance Simulation for vertical
30mrad
-30mrad
FOIL
QDL
H0 branch
PBH3
PBH4
BPM
QFM
100π paint injection orbit
x
QFL
QDL
1st Foil
ISEP1,2
(100pi paint bump orbit )
(shift bump orbit)
PB1,2
PB3,4
S
SB1
SB2
SB3
SB4
150π paint injection orbit
x
QFL
QDL
1st Foil
ISEP1,2
(150pi paint bump orbit )
(shift bump orbit)
PB1,2
PB3,4
S
SB1
SB2
SB3
SB4
200π paint injection orbit
x
QFL
QDL
1st Foil
ISEP1,2
(200pi paint bump orbit )
(shift bump orbit)
PB1,2
PB3,4
S
SB1
SB2
SB3
SB4
Loss Monitor signal of H0 branch
@single pass mode
Loss Monitor signal by K. Yamamoto
Integral Values
100πpaint
150πpaint
200πpaint
decrease
Loss Monitor signal of H0 branch
@circulating mode
Loss Monitor signal by K. Yamamoto
100πpaint
150πpaint
200πpaint
decrease
Loss Monitor signal of BPM
@single pass mode
Loss Monitor signal by K. Yamamoto
100πpaint
150πpaint
200πpaint
constant
Loss Monitor signal of BPM
@circulating mode
Loss Monitor signal by K. Yamamoto
100πpaint
150πpaint
200πpaint
decrease
Comparison of beam loss between
simulation and experiment
at ring inside of H0 branch
rate
1/3mode(simulation)
DCmode(simulation)
1/3mode(measurement)
DCmode(measurement)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
80
100
120
140
160
paint
180
200
220
Comparison of beam loss between
simulation and experiment
at ring inside of BPM
rate
1/3mode(simulation)
DCmode(simulation)
1/3mode(measurement)
Dcmode(measurement)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
80
100
120
140
160
paint
180
200
220