J-PARC 3GeV RCS???? ????? ~?????????????????

1
J-PARC 3GeV RCS??????????????????????????

• ????
• ?????/J-PARC????
• ????????2010_at_??
• 2010?11?12?

2
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
3
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 52
RF cavities 12 (11 at present)
Start of the beam commissioning October 2007
4
RCS Injection System
H-
3rd foil
QFL
QDL
2nd foil
MWPM3
To beam dump
MWPM5
MWPM4
x
ISEP1,2
s
PB1,2
PB3,4
1st foil
SB1
SB2
SB3
SB4
5
Horizontal Painting Injection Process
3rd foil
H-
QFL
QDL
2nd foil
To beam dump
MWPM3
MWPM4
MWPM5
1st foil
H
x
ISEP1,2
H-
s
H0
PB1,2
PB3,4
Circulating beam
Circulating beam
SB1
SB2
SB3
SB4
xmrad
H-
current
SB
xmm
124.1
93
0
PB
-4.4
Injection Beam
Painting Area
time
Injection period(500µsec)
6
Horizontal Painting Injection Process
3rd foil
H-
QFL
QDL
2nd foil
To beam dump
MWPM3
MWPM4
MWPM5
1st foil
H
x
ISEP1,2
H-
s
H0
PB1,2
PB3,4
Circulating beam
Circulating beam
SB1
SB2
SB3
SB4
xmrad
H-
current
SB
xmm
124.1
93
0
PB
-4.4
Injection Beam
Painting Area
time
Injection period(500µsec)
7
Horizontal Painting Injection Process
3rd foil
H-
QFL
QDL
2nd foil
To beam dump
MWPM3
MWPM4
MWPM5
1st foil
H
x
ISEP1,2
H-
s
H0
PB1,2
PB3,4
Circulating beam
Circulating beam
SB1
SB2
SB3
SB4
xmrad
H-
current
SB
xmm
124.1
93
0
PB
-4.4
Injection Beam
Painting Area
time
Injection period(500µsec)
8
Vertical Painting Injection process
y
y
s
MWPM3
MWPM5
MWPM4
VPB1
VPB2
y
H
H-
1st foil
9
Issue of beam loss _at_ injection section

• Radioactivity at Horizontal plane of HO branch
  and BPM
• 200µSv/h_at_20kW operation
• 1-2mSv/h_at_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 _at_ 20kW operation is 17 ?equals
  to calculation value of averaging foil hit counts
• ?Must identify the source of beam loss at high
  radioactivity points

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Issue of beam loss _at_ RCS Injection section
Ring Collimator
200µSv/h_at_20kW operation 1.2mSv/h_at_120kW operation
H0-Q
H0-Septum2
Circulating beam
H0-Septum1
QDL
(2)
(1)
BPM
H- injection beam
QFL
Foil
200µSv/h_at_20kW operation 2mSv/h_at_120kW operation
Circulating beam
11
Foil Scattering Distribution
Multiple Coulomb scattering
Multiple Coulomb scattering
foil
Nuclear scattering
Nuclear scattering
(p, p), (p, n) . . . .
Coulomb nuclear scattering
Coulomb nuclear scattering
rad
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/cm2)
?Select about 104 events of large scattering more
than 3mrad
12
Horizontal Phase Space _at_ 150p Painting Process
Foil
Foil
Foil
1 turn
10 turn
20 turn
Foil
Foil
Foil
30 turn
40 turn
50 turn
Foil
57 turn
Length between Injection beam position and Foil
edge?12mm Painting injection only for horizontal
direction
Particles w/ foil hit Particles w/o foil hit
13
Particle Tracking (1turn) _at_150p
3mrad
-3mrad
Total 2069
Total 1144
H0 branch
BPM
FOIL
QDL
QFM
PBH3
PBH4
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Particle Tracking (57turn) _at_150p
3mrad
-3mrad
Total 2293
Total 1080
H0 branch
BPM
FOIL
QDL
QFM
PBH3
PBH4
15
Estimation of residual radioactivity _at_150ppaint
for horizontal
QDL
FOIL
QFM
PBH3
PBH4
BPM
Total 1926
Total 1115
Assumption 1W/m 1mSv/h 1.2kW(47108)
220144counts (1.59m)
109034counts (0.1m)
161141counts (0.2m)
105899counts (1.36m)
278µSv/h
206µSv/h
35µSv/h
20µSv/h
16
Estimation of residual radioactivity _at_150ppaint
for vertical
Total 310
23_at_1turn ? 18766_at_circulating 18766events(0.1m)?48
µSv/h
Total 319
H0 branch
BPM
FOIL
QDL
QFM
PBH3
PBH4
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Solution of this issue(1)

• Current Foil Size (110mm x 40mm)
• Average Hit Count _at_ foil 8.77
• New Foil Size (110mm x 15mm)
• Average Hit Count _at_ foil 4.66

15mm
40mm
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20 turn
1 turn
Particles w/ foil hit Particles w/o foil hit
xrad
ym
xm
yrad
40 turn
60 turn
80 turn
94 turn
19
20 turn
1 turn
Particles w/ foil hit Particles w/o foil hit
xrad
ym
xm
yrad
40 turn
60 turn
80 turn
94 turn
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Solution of this issue(2)
H0 branch duct
Install the new collimator and shield at H0
branch duct for localization of this beam loss
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Example of localization
Total 1965
Total 1096
H0 branch
BPM
FOIL
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Example of localization
Total 1965
Collimator
Total 1306
H0 branch
BPM
FOIL
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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.

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Decay Curve of redial radioactivity1/3mode?ACmode
(Foil260µg/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
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Estimation of Loss Particle
1?????????????108????????????????????100µs????47??
??????????????????47 108???? ???????????????108??
?????????104??????????????????????????????
???????? ??????????? ( ?????? ??? )
??? (?) 1???? 100
100 ( 30000 30000
) 1 (?) 2???? 200
100 ( 30000
30000 ) 2 (?) 20???? 1000
100 ( 15000
30000 ) 20 (?) 57???? 1566
100 ( 10000
30000 ) 47
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Estimation of Loss Particle
?????? ?? ???? ??? (1/3) _at_??? ??? (??) _at_??? ?? (1/3vs??) _at_??? ??? (1/3) _at_BPM ??? (??) _at_BPM ?? (1/3???) _at_BPM
100p 22.9 7050 158924 22.5 10058 224060 22.3
150p 17.4 6439 109034 16.9 9635 161141 16.7
200p 14.2 5828 80559 12.9 9494 122879 12.9
47108???????????(???????47?????57?)
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?????????????
?2?6?
??????????? ?????????????????????????????????????
???? ?????????????????? ?????????????????????
?????100kW?? Simpsons?????????????????????????
(6.40, 6.42)
?? -0.4
?y 6
?????????????? ?y
?x 6
Laslett????????????
?????????????? ?x
nt ????Bf?????????? rp ????????e?????? ß,????
???????
1???? 2????
28
?????????????????
?2?6?
x
????????????????????????????????????????????????
??????????????????????
?????
x
?????
y
?????????
?? -0.4 ? -0.1
?????
y
?????
e ????????????ß,? ????Twiss parameter
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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)
CurvesDesign value, DotsMeasured values,
SolidsReconstructed value
1/3 ring (straightarc)
ßx, ßym
?x, ?ym
sm
We could make the optics almost fitted to the
design curves with no iteration.
The measured optics (tune, beta, dispersion) was
reasonably well reconstructed in our accelerator
model.
30
Control of Ring Optics
(?x,?y)(6.38,6.45) on 2008/05/26
(?x,?y)(6.40,6.42) on 2009/11/02
We can easily control the ring optics (betatron
tunes and beta amplitude functions) with good
accuracy!!
31
Measurement of Response Matrix for frequency
domain and Identification of Injection Phase Space
x0 injection position, x0 injection
derivative, ?x betatron tune, ax, ßx twiss
parameter _at_ 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
32
Measurement of response matrix
33
Correction of the injection mismatching
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
Injection beam
Closed orbit
Injection bump
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
34
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
35
Footprint of (x, x) over the painting injection
process
Single-short pulse injection (25 mA peak, 560 ns
long)
600ms
SB
PBH
500ms
? 1-pass BPM 1101-1102 ? PB magnet off at t5 ?
MWPM3-4
t0
t5
X(rad)
t0
150 p
200 p
100 p
t5
?110p
?163p
?220p
X(m)
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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
PBV
Y(rad)
t0
t5
(Correlate painting)
100 p
Y(m)
37
Acceptance Simulation
30mrad
-30mrad
H0 branch
BPM
QDL
QFM
PBH3
PBH4
FOIL
38
Result of Acceptance Simulation
Foil Edge
Loss up to branch
7mm
Loss up to BPM
30mrad
Survive through the Collimator
Loss at BPM
Loss up to BPM
Loss up to branch
39
Acceptance Simulation for vertical
30mrad
-30mrad
H0 branch
BPM
FOIL
QDL
QFM
PBH3
PBH4
40
100p 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
41
150p 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
42
200p 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
43
Loss Monitor signal of H0 branch_at_single pass mode
Loss Monitor signal by K. Yamamoto
Integral Values
100ppaint
150ppaint
decrease
200ppaint
44
Loss Monitor signal of H0 branch_at_circulating mode
Loss Monitor signal by K. Yamamoto
100ppaint
150ppaint
decrease
200ppaint
45
Loss Monitor signal of BPM_at_single pass mode
Loss Monitor signal by K. Yamamoto
100ppaint
constant
150ppaint
200ppaint
46
Loss Monitor signal of BPM_at_circulating mode
Loss Monitor signal by K. Yamamoto
100ppaint
150ppaint
decrease
200ppaint
47
Comparison of beam loss between simulation and
experiment at ring inside of H0 branch
48
Comparison of beam loss between simulation and
experiment at ring inside of BPM