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A superconducting rotating gantry for heavy-ion therapy is being designed. This isocentric rotating gantry can transport heavy ions with the maximum energy of 430 MeV=u to an isocenter with irradiation angles of over 0-360 degrees, and is further capable of performing three-dimensional raster-scanning irradiation. The combined-function superconducting magnets will be employed for the rotating gantry. The superconducting magnets with optimized beam optics allow a compact gantry design with a large scan size at the isocenter; the length and the radius of the gantry will be approximately 13 and 5.5 m, respectively, which are comparable to those for the existing proton gantries. Furthermore, the maximum scan size at the isocenter is calculated to be as large as approximately 200 mm square for heavy-ion beams at the maximum energy of 430 MeV=u. Based on the design of the beam optics, specifications of the superconducting magnets were determined. The superconducting magnets and magnetic-field distributions are designed using a three-dimensional field solver. With the calculated magnetic fields, beam-tracking simulations were performed to verify the design of the superconducting magnets, and concurrently to evaluate the field quality. With calculated beam profiles at the isocenter, we found that the positions of beam spots as well as their size and shape could be well reproduced as designed, proving validity of our design.

The flame retardancy and the rearrangement reaction of polyphenyleneether [poly-(oxy-2,6-dimethyl-1,4-phenylene), PPE] and polyphenylene-ether/polystyrene (PS) alloys have been studied. The flame retardancy of PPE blended with phosphates was proportional to PPE content as well as to the phosphates. The surface temperatures of PPE during a combustion was higher than that of PS, whereas PPE is more flammable than PS. The element analysis of the polymer surface showed that carbon was richer compared with the content of the newly synthesized PPE. Four monomeric and eight dimeric scission products were recovered by thermogravimetricmass (TGA-MASS) analysis at high temperature in inert atmosphere. These structures of the scission products suggested that the rearrangement reaction occurred in combustion at high temperature. Namely, the formation of carbonaceous materials on the surface followed the rearrangement reaction and dehydration which was accelerated by the addition of aromatic phosphates.

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