commissioning of new beam intensity...
TRANSCRIPT
Kota Mizushima #,A),B), Takuji FurukawaA), Toshiyuki ShiraiA), Shinji SatoA), Yoshiyuki IwataA),
Ken KatagiriA), Eri TakeshitaA), Akihiro HigashidaA),B), Koji NodaA) A) Department of Accelerator and Medical Physics, National Institute of Radiological Sciences,
4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan B) Graduate School of Science and Technology, Chiba University,
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
Abstract NIRS has carried out three-dimensional scanning irradiation for carbon-ion radiotherapy at the HIMAC new
treatment research facility since May 2011. In this irradiation, we have adopted a raster scan method to make the
lateral dose distribution. For the reduction of the difference between prescribed and delivered dose distribution, it is
preferable that the extracted beam-current from the synchrotron ring is low ripple, and the response to the beam-on/off
switching is quick. To meet these requirements, we have developed a new beam-intensity control system with the RF-
knockout slow extraction and feedback control system. In the system commissioning, we can modulate the beam-
intensity in the range of thirty times while keeping the beam-current ripple below 20%.
HIMAC æ°ããŒã 匷床å¶åŸ¡ã·ã¹ãã ã®ã³ããã·ã§ãã³ã°
1. ã¯ããã«
æŸå°ç·å»åŠç·åç 究æïŒNIRSïŒ[1]ã§ã¯ãéç²åç·ããæ²»ççšå éåš HIMAC ãçšããŠã1994 幎ã®æ²»çéå§ä»¥æ¥ã5000 å以äžã®æ£è ã«å¯ŸããŠéç²åç·æ²»çãè¡ã£ãŠãããæŽãªãæ²»çç §å°ã®é«ç²ŸåºŠåãç®æãããããŸã§ã®æ¡å€§ããŒã ç §å°æ³ã«ããæ²»çãšäžŠè¡ããŠã2010 幎ã«å®æããæ°æ²»çç 究æ£ã§ã2011
幎 5 æãã 3 次å ã¹ãã£ãã³ã°ç §å°æ³ã«ããæ²»çãè¡ãããŠããã
NIRS ã¹ãã£ãã³ã°ç §å°[2]ã§ã¯ãäžæ¬¡å çãªç·éååžã®åœ¢æã«ããã€ããªããã©ã¹ã¿ãŒã¹ãã£ã³æ³[3]
ãšã¬ã³ãžã·ãã¿ãŒãšåŒã°ããè€æ°æã®åãã®ç°ãªãPMMA ãã¬ãŒããçšããŠããããã€ããªããã©ã¹ã¿ãŒã¹ãã£ã³æ³ã§ã¯ãã¿ãŒã²ããå ã«é 眮ãããã¹ããããšåŒã°ããå°é åæ¯ã«ç §å°ç·éãå¶åŸ¡ããã¹ããã移åéãããŒã ãåæ¢ããªãããšã§ãé«éãªã¹ãã£ãã³ã°ç §å°ãå¯èœãšãªãããã®ãããã¹ãããéç·éãæ£ç¢ºã«ç®¡çããããšãéèŠãšãªãããNIRS ã¹ãã£ãã³ã°ã·ã¹ãã ã§ã¯ãããŒã 匷床ãäžå®ã«ä¿ã€ããšã§å¶åŸ¡å¯èœã«ããŠãããã¬ã³ãžã·ãã¿ãŒé§åäžã¯ãããŒã ãäžæåæ¢ããé§åå®äºãšãšãã«ããŒã åºå°ãåéããããã®ããŒã ãªã³ã»ãªãã®åãæ¿ã㯠1 åã®æ²»çç §å°ã§æ°ååçšåºŠè¡ããããèšç»ç·éãšå®ç §å°ç·éã®ååžèª€å·®ãæžããããã«ãç §å°ããŒã 匷床ã®æéå€åãæããããŒã ãªã³ã»ãªãã®å¿çæéãéãããããšãæ±ãããããæŽã«ãã¹ãã£ãã³ã°é»ç£ç³æ§èœãæ倧éã«æŽ»ãããç §å°æéãççž®ããããã«ã¯ãããŒã 匷床ãã¹ã©ã€ã¹æ¯ã«å€ããããããšãæãŸããããããèŠæ±ã«å¿ãããããéå»ã®ç 究 [4]ã«åºã¥ããRF ããã¯ã¢ãŠãïŒRFKOïŒæ³[5]ãçšããããŒã 匷床ãã£ãŒãããã¯å¶åŸ¡ã·ã¹ãã ãæ°ãã«éçºããæ°æ²»çç 究æ£ã«ãããŠã·ã¹ãã ã®ã³ããã·ã§ãã³ã°ãè¡ã£ãã
2. ããŒã 匷床å¶åŸ¡ã·ã¹ãã
2.1 ã·ã¹ãã ã®æŠèŠ
HIMAC ããŒã 匷床å¶åŸ¡ã·ã¹ãã ã¯ãå³ 1 ã«ç€ºãããããã¯ãã€ã¢ã°ã©ã ã®ããã«ã2 å°ã® RFKO å¶åŸ¡åšïŒRFC1, RFC2ïŒãšã·ã¹ãã ã·ãŒã±ã³ã¹å¶åŸ¡åšïŒSCïŒã§æ§æããããããããã® RFC ã¯ãLow-
Level RF ä¿¡å·çºçåšãšãã£ãŒãããã¯æ¯å¹ å¶åŸ¡åšãšããŠã®äºã€ã®æ©èœã䜵ãæã€ãããŒã 匷床ãã£ãŒãããã¯å¶åŸ¡ã®ããã«ãç §å°ããŒãã«ããé»é¢ç®±ãšããŒã ãã³ãã·ã£ãã¿ãŒæåã«ããäºæ¬¡é»åã¢ãã¿ãŒïŒSEMïŒãçšããŠãããããããã®æž¬å®å€ã¯IFC åè·¯ãéã㊠2 å°ã® RFC ã«å ¥åããããããŒã 匷床ç®æšå€ã¯ãç §å°å¶åŸ¡ã·ã¹ãã ïŒNIRRïŒã«ãã£ãŠèšå®ãããããŸããHIMAC ã·ã³ã¯ãããã³ããäŸçµŠããããŒã ãšãã«ã®ãŒã¯ãå¯å€ãšãã«ã®ãŒã³ã³ãããŒã©ïŒVEïŒã«ãã£ãŠå¶åŸ¡ããããããŒã ãªãäžã«ã¯ãããŒã æŒããé²ãããã«ããªã³ã°å ã® 2 å°ã®é«éå極é»ç£ç³ïŒQDSïŒãå±ç£ããŠãå ±é³Žæ¡ä»¶ã
å³ 1ïŒHIMAC ããŒã 匷床å¶åŸ¡ã·ã¹ãã _______________________________________
NIRR
Beam-intensity control system
Scanner
magnets
Ion chamber
PMMA plates
SEM
Beam dump shutter
Robotic
treatment couch
VEHIMAC timing system
SC
RFC1
RFC2
QDS PS
+
Flattop status
Summing
amplifier
400W RF
power amplifier
RF-KO
kicker
QDS1
QDS2
Reinjection request
RF-on status
RF-on status
RF-output
RF-output
Measurement signal
Measurement signal
QDS gate
Preheating gate
Beam-on gate
Shutter gate
Beam request
Beam-intensity
set point
OR
Reinjection
orderDCCT
Circulating beam-current
COMMISSIONING OF NEW BEAM INTENSITY CONTROL SYSTEM AT HIMAC
Proceedings of the 8th Annual Meeting of Particle Accelerator Society of Japan (August 1-3, 2011, Tsukuba, Japan)
- 700 -
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2.2 RFKO å¶åŸ¡åš
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ã²ã€ã³ã¯ãPI å¶åŸ¡ã«ãã 0.1 ms æ¯ã«å€èª¿ããããDDS1, DDS2 ãšãDDS3 ã®é»å§æ¯ã倧ããã»ã©ãããŒã ãªã³æã«çããããŒã é»æµã¹ãã€ã¯ãæžãããããšãåãã£ãŠãããã ãäžæ¹ã§ããã£ãŒãããã¯ã«å¯ŸããããŒã é»æµã®å¿çãéããªãããšãããããŒã ãªã³æã«ãªãŒããŒã·ã¥ãŒããªã©ã«ãã£ãŠãããŒã 匷床ãäžå®å®ã«ãªããããããšãæ°ãã«ããã£ãïŒå³ 3ïŒaïŒïŒããã®äžå®å®æ§ãé¿ãããããå DDS ã®åŸæ®µã«ãæéå¶åŸ¡ã§é»å§æ¯ãå€åãããããã® VCA ãèšããããã® 3 å°ã® VCA ã§ãRF åºåéå§ãã 1 ms ã§é»å§æ¯ã 1:1:1 ãã 1:1:2 ã«ãªãããã«ã²ã€ã³ãå€åãããŠããïŒå³ 3ïŒbïŒïŒãããã«ãããããŒã 匷床㚠RFKO é»å§ã®æ»ãããªç«ã¡äžãããå®çŸã§ããã
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2.3 ãã©ããããã延é·é転
NIRS ã¹ãã£ãã³ã°ç §å°ã¯ãã·ã³ã¯ãããã³ã®ããŒã ãšãã«ã®ãŒå¯å€ãã¿ãŒã³ãšãã©ããããã延é·é転ãçšããŠãã[8]ïŒå³ 4ïŒãããã«ãããã·ã³ã¯ãããã³ã®ãã¥ãŒãã£æ¯ãæ倧éã«åäžãããç §å°æéã®ççž®åãç®æããŠãããçŸåšã®æ²»çç §å°ã§ã¯ãå³ 4ïŒbïŒãïŒcïŒãïŒdïŒã®ããã«ãç §å°éšäœã®æ·±ãã«åããã 1 ãšãã«ã®ãŒæ®µã®ã¿ã䜿çšããŠããããå°æ¥çã«ã¯ãå³ 5 ã«ç€ºããããã«ãç §å°äžã«ã·ã³ã¯ãããã³ã§é£ç¶çã«ããŒã ãšãã«ã®ãŒå€æŽãè¡ããåãã¬ã³ãžã·ãã¿ãŒã®äœ¿çšã«ããããŒã ãµã€ãºã®å¢å€§ãé²ããæçµçã«ã¯ããšãã«ã®ãŒæ®µãå¢ããããšã§ã·ã³ã¯ãããã³ã§ã®ãšãã«ã®ãŒå€æŽã®ã¿ã§æ²»çç §å°ãè¡ãããšãç®æšãšããŠããã
ãã©ããããã延é·é転ã«ãããŠãäžç §å°å®äºã«
å³ 4ïŒ11 段é転ãã¿ãŒã³ãšãã©ããããã延é·é転
å³ 5ïŒ11 段é£ç¶ããŒã ãšãã«ã®ãŒå¯å€åãåºã
å³ 6ïŒãã£ãŒãããã¯ã²ã€ã³éŸå€ã«ããåå ¥å°å¶åŸ¡
a
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0
300
600
900
1200
Beam intensity
Current IQDS
Time [ms]
Bea
m i
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ty [
kcp
s]
-8.0
-4.0
0.0
Cu
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S [A]
0
20
40
60
80
100
RF voltage
Gain ratio G2 / G
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vo
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0.0
1.0
2.0
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2 / G1
-4 0 4 8 12 16 20 24
0
300
600
900
1200
Beam intensity
Current IQDS
Time [ms]
Bea
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ty [
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-8.0
-4.0
0.0
Cu
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0
20
40
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Gain ratio G2 / G
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0.0
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IBM
Time
IBM
Time
IBM
Time
430 MeV/n
350 MeV/n
290 MeV/n
a
b
c
d
0 1000 2000 30000
200
400
600
800
1000
1200
1400
Cu
rren
t I
BM
[A
]
Time [ms]
0 20 40 60 80 100 120
0
200
400
600
800
1000
1200
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0
20
40
60
80
100
120
140
160
Beam intensity
Beam-on gate
Preheating gate
Beam
in
ten
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[k
cp
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Time [s]
Reinjection level
RF
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Current IBM
Circulating beam current
RF voltage
DDS1 DDS2 DDS3
DAC1 DAC2 DAC3
DDS control unit
Feedback control unit
RF-on/off control unit
VCA
VCA
VCA
VCA
AdderRF switch
10mW RF
power amplifier
RF-output
RF-on status
Beam-on gateReinjection order
Measurement signal
Beam-intensity set point
Proceedings of the 8th Annual Meeting of Particle Accelerator Society of Japan (August 1-3, 2011, Tsukuba, Japan)
- 701 -
è¡š 1 å®éšãã©ã¡ãŒã¿ãŒ
Energy of 12C6+ 430 MeV/n 350 MeV/n 290 MeV/n
Betatron tune (Qx/Qy) 3.679/3.131 3.679/3.128 3.679/3.133
Revolution frequency 1.687 MHz 1.589 MHz 1.497 MHz
Extraction beam rate 7.6 Ã 106 â
2.3 Ã 108 pps
8.4 Ã 106 â
2.5 Ã 108 pps
9.3 Ã 106 â
2.8 Ã 108 pps
FM center frequency of transverse RF-field 1.149 MHz 1.084 MHz 1.021 MHz
Bandwidth of FM 6.0 kHz 7.9 kHz 7.5 kHz
Single frequency of transverse RF-field 1.138 MHz 1.074 MHz 1.012 MHz
å¿ èŠãªç²åæ°ãã·ã³ã¯ãããã³äžåšæã§ç¢ºä¿ã§ããªãå Žåã«ã¯ãããŒã ã®åå ¥å°å¶åŸ¡ãè¡ããªããã°ãªããªãããã®ãããããŒã 匷床å¶åŸ¡ã·ã¹ãã ã§ã¯ããªã³ã°å ã® DCCT ã¢ãã¿ãŒãçšããŠãåšåããŒã é»æµã®éŸå€å¶åŸ¡ã«ããåå ¥å°ã¿ã€ãã³ã°å¶åŸ¡ãè¡ã£ãŠããããŸããå³ 6 ã«ç€ºããããã«ããã£ãŒãããã¯å¶åŸ¡é»å§ã«ãéŸå€ãå ããããšã§ãæ§ã ãªç¶æ å€åã«å¯ŸããŠããæè»ã«å®å®ããå¶åŸ¡ãå®çŸããŠããã
2.4 ããŒã ãã¬ããŒãã£ã³ã°
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Proceedings of the 8th Annual Meeting of Particle Accelerator Society of Japan (August 1-3, 2011, Tsukuba, Japan)
- 702 -
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0
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Sta
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350 MeV/n
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[1] Y. Hirao et al., Nucl. Phys. A 538 (1992) 541. [2] T. Furukawa et al., Med. Phys. 37 (2010) 5672. [3] Th. Haberer et al., Nucl. Instr. and Meth. A 330 (1993)
296. [4] S. Sato et al., Nucl. Instr. and Meth. A 574 (2007) 226. [5] M. Tomizawa et al., Nucl. Instr. and Meth. A 326 (1993)
399. [6] K. Noda et al., Nucl. Instr. and Meth. A 492 (2002) 253. [7] K. Mizushima et al., Nucl. Instr. and Meth. A 606 (2009)
325. [8] Y. Iwata et al., Nucl. Instr. and Meth. A 624 (2010) 33.
Proceedings of the 8th Annual Meeting of Particle Accelerator Society of Japan (August 1-3, 2011, Tsukuba, Japan)
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