Direct injection of laser-accelerated ions into a superconducting synchrotron

One of the development themes of Quantum Knife Project carried by QST is to miniaturize of the heavy-ion radiotherapy equipment by use of superconductive technology and laser particle acceleration technology. Feasibility study on a direct injection into a synchrotron of a laser-accelerated ions was performed. In the previous report, it was indicated that the consideration with the current heavy-ion therapy synchrotron was made and a possibility of accumulating 1×10⁹ particles or more. In this report, the number of captured particles per shot was examined, using the superconducting synchrotron being studied in this project. Furthermore, the beam transport was also studied from the ion production point to the injection point of the synchrotron. As a result, the following was found out. After flying laser-accelerated ions with energy of 4 MeV/u ± 6% during about 1.7 m, energy compression of 1/10 is made by the phase rotation. After that, the beam is shaped and injected into the synchrotron. The number of captured particles in the synchrotron per shot was 1×10⁸ on average as a result of taking into consideration the space charge effect, the energy spread of the ions, and the dispersion of the particle number produced by the laser. From this, it is possible to accumulate 1×10⁹ or more particles by performing the multiple incidence of 20 times with a 10 Hz laser. (author)