| Paper | Title | Page |
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| WEPCH169 | Alternating Phase Focused IH-DTL for Heavy-ion Medical Accelerators | 2328 |
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Tumor therapy using HIMAC has been performed at NIRS since June 1994. With the successful clinical results over more than ten years, a number of projects to construct these complexes have been proposed over the world. Since existing heavy-ion linacs are large in size, the development of compact linacs would play a key role in designing compact and cost-effective complexes. Therefore, we developed an injector system consisting of RFQ and Interdigital H-mode (IH) DTL having the frequency of 200 MHz. The injector system can accelerate carbon ions up to 4.0 AMeV. For the beam focusing of IH-DTL, the method of Alternating Phase Focusing (APF) was employed. With the IH structure and rather high frequency, the cavity size is compact; the radius is 0.4 m, and lengths of RFQ and IH-DTL are 2.5m and 3.5m respectively. The fabrication of RFQ was completed, and we succeeded to accelerate carbon ions with satisfactory performances. For IH-DTL, the full-scale model was first fabricated. With the encouraging result* of its electric field measurement, we constructed IH-DTL and beam acceleration tests will be performed in March 2006. We will present the performances of the entire injector system.
*Y. Iwata et al., Nucl Instr. & Meth in Phys. Res. A (submitted). |
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| THPCH155 | High-quality Proton Beam Obtained by Combination of Phase Rotation and the Irradiation of the Intense Short-pulse Laser | 3158 |
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| Ion production from laser-induced plasma has been paid attention because of its high acceleration gradient (>100GeV/m) compared with conventional RF accelerator. Its energy spectrum is Maxwell-Boltzmann distribution with high-energy cut-off, which limited its application. The phase rotation scheme, which rotates laser produced ions by an RF electric field synchronous to the pulse laser in the longitudinal phase space, was applied to proton beam up to 0.9MeV emitted from Ti foil with 3mm thickness irradiated by focused laser-pulse with peak intensity of 9 ´ 1017W/cm2. Multi-peaks with ~6% width (FWHM) were created and intensity multiplication up to 5 was attained around 0.6MeV region. The proton production process by the intense short-pulse laser has been optimized with use of time of flight measurement of proton beam detected by a plastic scintillation counter, which is specially shielded from the heavy background of electrons and X-rays induced by the intense laser. We have succeeded in on-line measurement of such a proton signal by the detector for the first time, which played an essential role for the investigation of phase rotation scheme. |