| Paper | Title | Page |
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| TUPLS079 | Hadron Cancer Therapy Complex Employing Non-scaling FFAG Accelerator and Fixed Field Gantry Design | 1681 |
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| Non-scaling FFAG rings for cancer hadron therapy offer reduced physical aperture and large dynamic aperture as compared with scaling FFAGs. The variation of tune with energy implies the crossing of resonances during acceleration. Our design avoids intrinsic resonances, although imperfection resonances must still be crossed. We consider a system of three non-scaling FFAG rings for cancer therapy with 250 MeV protons and 400 MeV/u carbon ions. Hadrons are accelerated in a common RFQ and linear accelerator, and injected into the FFAG rings at v/c=0.1128. The H+/C6+ ions are accelerated in the two smaller/larger rings to 31 and 250 MeV/52.5 and 400 MeV/u kinetic energy, respectively. The lattices consist of symmetrical triplet cells with a straight section for RF cavities. The gantry with similar triplet cells accepts the whole required momentum range at fixed field. This unique design uses either High Temperature super-conductors or super-conducting magnets reducing gantry size and weight. Elements with a variable field at the beginning and at the end set the extracted beam at the correct position for the specific energy and adapt the beam to specific requirements during treatment. | ||
| WEPCH060 | Linear and Nonlinear Coupling Using Decoupling Transformations | 2059 |
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| Linear coupling in a storage ring is conveniently analyzed in terms of transformations that put the single-turn map into block-diagonal form. Such a transformation allows us to define new variables, in which the dynamics are uncoupled. Thus, for example, the symplectic conditions are simply that the phase area in each of the uncoupled variables is preserved. In principle, a similar approach may be taken to nonlinear coupling; we discuss such an approach in this paper, giving some simple illustrations of the ideas, based on the well-known techniques of normal form analysis. We also discuss some obstacles to finding a nonlinear decoupling transformation in the general case. | ||
| WEPCH101 | Ion Motion in the Adiabatic Focuser | 2149 |
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The Adiabatic Focuser* works by having a focusing channel whose strength increases with distance down the channel. In this situation electrons of various energies and various transverse oscillation phase all are transversely focused. The concept works with external focusing, but would be very effective in a plasma ion focusing channel where the density of ions is simply increased as one goes down the channel. In the original work (Ref 1) motion of the ions was not included (as it was assumed to be a small effect). Recently, it has been suggested that ion motion in an adiabatic focuser would be significant and, even, preclude operation of the focuser as previously envisioned**. In this paper we numerically study the ion motion in the focuser. The ions clearly influence each other and, most importantly, are influenced by the electric field of the electrons being focused. It is shown that parameters can be selected such that the adiabatic focuser works as well as originally envisioned.
*P. Chen et al. Phys. Rev. Lett. 64, 1231 (1990).**J. R. Rosenzweig, et al. Phys. Rev. Lett. 95, 195002 (2005). |
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| WEPCH180 | A Dramatically Reduced Size in the Gantry design for the Proton-Carbon Therapy | 2352 |
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| Gantries in the proton/carbon cancer therapy machines represent the major cost and are usually very large. This report explains a new way for the gantry design. The size and cost of the gantries are reduced, and their use is simplified by using the fixed magnetic field. The "new" gantry is made of a very large momentum acceptance non-scaling Fixed Field Alternating Gradient (FFAG) quarter and half arc beam lines. The gantry is made of combined function magnets with a very strong focusing and small dispersion function. Additional magnets with a fast response are required to allow adjustments of the beam position for different energies at the beginning of the gantry. The strong focusing magnets following the gantry have to be adjustable as well to provide the required spot size. The adjustable dipoles provide the radial scanning. The fixed field combined function magnets could be made of small permanent magnets for the proton machine, or of the high temperature superconductors or superconductors for the carbon machine, reducing dramatically the size. | ||
| THPCH028 | Crystalline Beams at High Energies | 2841 |
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Previously it was shown that by crystallizing each of the two counter-circulating beams, a much larger beam-beam tune shift can be tolerated during the beam-beam collisions; thus a higher luminosity can be reached for colliding beams*. On the other hand, crystalline beams can only be formed at energies below the transition energy of the circular accelerators**. In this paper, we investigate the formation of crystals in two types of high-transition-energy lattices, one realized by three-cell missing dipole modules and the other with negative bends. The latter type satisfies the maintenance condition for a crystalline beam***.
*J. Wei and A.M. Sessler, “Colliding crystalline beams”, EPAC98, p. 862. **J. Wei et al. Physical Review Letters, 73 (1994) p. 3089.***J. Wei et al. Physical Review Letters, 80 (1998) p. 2606. |