MEASUREMENT OF ISOCHRONISM OF RIBF CYCLOTRONS Ryo Koyama 1, A), B), Masaki Fujimaki A), Nobuhisa Fukunishi A), Akira Goto A), Masatake Hemmi A), Masayuki Kase A), Naruhiko Sakamoto A), Tamaki Watanabe A), Kazunari Yamada A), and Osamu Kamigaito A) A) RIKEN Nishina Center for Accelerator-Based Science 2-1 Hirosawa, Wako, Saitama, 351-0198 B) SHI Accelerator Service Ltd. 1-17-6 Osaki, Shinagawa, Tokyo, 141-0032 Abstract The 6-20 phase probes (PPs) are installed in the all cyclotrons of RIBF for non-destructive measurement of their isochronism. We have measured isochronism by observing the zero-cross points of bunch signals from PPs using an oscilloscope for nearly 20 years. We have developed new measuring system of isochronism using a lock-in amplifier for commissionings of 3 new cyclotrons started at 2006. In order to investigate the consistency of those two measuring methods of isochronism, we measured the isochronism using an oscilloscope and lock-in amplifier simultaneously. Additionally, we have performed Fourier analysis to bunch signals observed using an oscilloscope to investigate the difference of beam phases between frequency components. RIBF RI (RIBF) [1] 4 (RRC, frc, IRC, SRC) RILAC AVF 6 20 (Phase Probe: PP) 1.1 RIBF PP RIBF 2 1986 RRC 20 PP AVF RRC 2006 frc IRC SRC (LIA) [2] frc IRC SRC LIA 20 LIA 1 LIA 10 1.1 RIBF 2 2.1 RIBF (Phase Probe: PP) PP RIBF PP ( ) 2.1 PP PP#1 PP#2 PP#3 1 E-mail: rkoyama@riken.jp 25
2.1 RIBF [mm] [ ] ( ) [mm] AVF 6 80 80 25 RRC 20 100 100 26 frc 14 100 100 26 IRC 15 #1~5: 70 80 #6~15: 70 100 26 SRC 20 73 123 30 2.2 LIA-SR844 2.2 1986 RRC 20 PP PP PP 2.1 PP PP PP LIA 2.3 SRC PP#1 1f 2f S/N 2.1 AVF RRC 2.3 (LIA) V I (t) = V I sin(ω R t+θ I ) V R (t) = V R sin(ω R t+θ R ) V, ω, t, θ 2 V M V M = V I V R sin(ω R t+θ I )sin(ω R t+θ R ) = 1/2V I V R cos(θ R -θ I )+1/2V I V R sin(2ω R t+θ R +θ I ). (2-1) (2ω R ) (LPF) DC Stanford Research System LIA-SR844( 25 k 200 MHz 80 db) Digital Signal Processor(DSP) ( 2.2 ) 26 2.3 SRC PP#1 frc IRC SRC LIA 3.1 2006 frc IRC SRC LIA 2 1) 20 LIA 2) LIA LIA
1 1) PP 2 LIA 2) 10 PP LIA LIA PP 3.2 LabVIEW 1) 1.2 500 RIBF (Agilent DSO6000 series 500 MHz) 2) 4 3) Fast Fourier Transform (FFT) 10 PP 10 FFT 3.3 3.1 1) PP (2.1 ) PP 1 RIBF 5 3.1-6dB (HUBER+SUHNER/4901.01) LIA 2) PP ( ) (Agilent E4426B) LIA LIA 2.3 S/N 3) LabVIEW PP FFT LIA 4.1 FFT SRC 4.1 SRC 14 N 5+ 27.4 MHz 88.4 MeV/u 600 ena 250 MeV/u 300 ena S/N LIA SRC RF 3 (3f) 3.1 3.1 1) 2) 3) 4.1 SRC 27
4.1 SRC PP (nsec) 1 10 FFT LIA 1 nsec 0.5 nsec ( 5 ) 10 RRC 4.2 40 N 17+ 28.1 MHz 5.2 MeV/u 1500 ena 95 MeV/u 900 ena LIA RRC RF 2 (2f) 4.2 FFT LIA FFT LIA 3 4.4 FFT LIA (SRC 3f RRC 2f) 4.1 RF ( ) 4.4 a)src b)rrc FFT LIA 3 4.2 RRC RRC 0.5 nsec ( RF 5 ) 10 PP#1 #3 FFT- 9f ( ) PP-#3 4.3-a 9f -b 9f PP#1 PP#2 SRC 2 FFT LIA 3 RRC PP#1 #3 9f (4.1 ) SRC FFT LIA RRC FFT LIA SRC RRC 4.5 4.5 (#1) (#10) (#20) PP (a) SRC b) RRC) 4.3 RRC-PP#2 #3 a) b) a b 9f 28 SRC ( ) RRC (#20) (#1) 60% (4.4 ) SRC RRC tail ( sin cos ) RRC
4.3 RRC 1) ( ) 2) 3-Gaussian 2 fitting 3) fitting 3-Gaussian 4) PP#1 #20 5) 20 3.2 10 PP 4.6 RRC-PP RRC RF ( ) 4.6 4.4-b FFT-2f 4.7 PP#1 #3 9f (4.1 ) 2 SRC ( 4.4-a) 4.7 RRC 4.4 RRC 2 1) PP SRC 1.5 RRC 4 ( ) RRC PP RRC SRC ( 2.1 ) PP RRC SRC PP 2) [3] SRC 1.2 RRC 1.5 SRC RRC LIA LIA LIA 2 RRC 10 SRC RRC 0.5 nsec ( 5 ) 10 RRC ( 9 ) LIA LIA m 1 LIA [1] Y. Yano, Nucl. Instr. & Meth. B261 (2007) 1009. [2] R. Koyama et al., Proc. of PASJ4-LAM32, Wako-shi Saitama, Japan (2007), WP38. [3] T. Fujisawa et al., Nucl. Instr. & Meth. A 292 (1990) 1. 29