Evaluation of phase bunching in the central region of a cyclotron by a radial probe with a plastic scintillator

宮脇 信正; 福田 光宏*; 倉島 俊; 柏木 啓次; 奥村 進; 荒川 和夫*; 神谷 富裕

Nuclear Instruments and Methods in Physics Research A, 767, p.372 - 378, 2014/12

https://doi.org/10.1016/j.nima.2014.09.006

A new technique was developed for evaluating the phase bunching performance in the central region of a cyclotron. The performance in the JAEA AVF cyclotron was evaluated by measurements of the internal beam phase distribution with the beam buncher phase. The developed phase distribution measurement system for the internal beam comprised of a newly-developed radial probe with a plastic scintillator and the signal-processing modules. The small plastic scintillator with 6-mm width and 5-mm height had sufficiently high time resolution of 45 ps full-width at half-maximum for evaluating the phase bunching performance. The internal beam phase width was compressed to less than a half of the injected beam phase width in the acceleration harmonic number = 2 for a 260-MeV Ne beam, and the phase bunching effect was observed. On the other hand, the internal beam phase width was larger than the injected beam phase width in = 1 for a 107-MeV He beam and no evidence of the phase bunching effect was observed. These results were consistent with the calculation result of the theoretical geometric trajectory analysis.