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He, Z.*; Wei, J.*; 大崎 一哉*; 岡本 宏巳*; 野田 章*; 中尾 政夫*; 想田 光*; 百合 庸介; 神保 光一*
Proceedings of 25th North American Particle Accelerator Conference (NA-PAC '13) (Internet), p.1298 - 1300, 2013/09
The power of the cooling laser currently available in a compact ion cooler ring S-LSR, Kyoto University, is quite limited for generating ultralow-temperature ion beams. Therefore, parameters of laser cooling should be carefully determined in order to approach the lowest possible temperature in the experiment. This paper mainly concerns optimization of laser-cooling parameters and prediction of a possible lower limit of beam temperature in S-LSR, based on systematic molecular dynamics simulations. The adiabatic capture process of the ion beam was introduced to prevent the emittance from blowing up during bunching. The spot size of the laser was optimized with the total laser power limited. An optimum solenoid field strength was obtained for three-dimensional cooling. The lowest beam temperature achievable in S-LSR was predicted by choosing the parameters optimized.
神保 光一*; 想田 光*; 百合 庸介; 頓宮 拓*; 中尾 政夫*; 白井 敏之*; 野田 章*
Proceedings of 25th North American Particle Accelerator Conference (NA-PAC '13) (Internet), p.886 - 888, 2013/09
The synchrotron-oscillation signals of 40-keV bunched Mg
ion beams were investigated for the diagnostics of the laser-cooled beams in an ion cooler storage ring, S-LSR, Kyoto University. The signals induced on a parallel-plate pickup were measured with a spectrum analyzer. The coherent and incoherent modes corresponding to the synchrotron tune were observed in the signals. The molecular dynamics simulation predicts, on the other hand, that the synchrotron oscillation of the strongly laser-cooled beam is suppressed by the space-charge force. We thus propose a possibility to detect the space-charge limit by the observation of the predicted suppression of the synchrotron oscillation.
百合 庸介
Proceedings of 25th North American Particle Accelerator Conference (NA-PAC '13) (Internet), p.1434 - 1436, 2013/09
The molecular dynamics approach with the stochastic interaction effect between laser photons and ions is employed to study the formation of three-dimensionally ultralow-temperature ion beams by means of laser cooling in a storage ring. The efficiency of three-dimensional (3D) laser cooling of a coasting beam was investigated by the combination of horizontally-displaced lasers and resonant coupling at several different operating points. It was found that the indirect transverse cooling efficiency depended on the displacement and detuning of the lasers as well as on momentum dispersion. A string crystalline state of the beam was attained at low line density by 3D cooling. At higher line density, on the other hand, 3D ordered structures was formed depending on laser-cooling conditions.
百合 庸介; 石坂 知久; 湯山 貴裕; 石堀 郁夫; 奥村 進
Proceedings of 25th North American Particle Accelerator Conference (NA-PAC '13) (Internet), p.1388 - 1390, 2013/09
Radiochromic films, Gafchromic HD-810 and EBT2, were investigated in terms of their response to energetic proton and heavy-ion beams in order to be applied to a measurement technique of the transverse beam intensity distribution at the cyclotron of JAEA. The optical density of the irradiated films increased linearly with the particle fluence of the beam in a low-fluence region. The linear-response range was strongly dependent on ion species as well as the film type. By analyzing the film response to absorbed dose, it was found that the sensitivity of the film decreased for a beam with higher linear energy transfer. Based on the linear response above, we could successfully evaluate the relative intensity distribution of a large-area ion beam focused with multipole magnets. It was demonstrated that the present technique was useful for the estimation of the size and uniformity of the ion beam.
