EPAC 2006 - Classification:04 Hadron Accelerators/A12 FFAG, Cyclotrons

04 Hadron Accelerators

A12 FFAG, Cyclotrons

Paper	Title	Page
TUPLS027	A Non-scaling FFAG for Radioactive Beams Acceleration (RIA)	1547
	D. Trbojevic, T. Roser, A.G. Ruggiero BNL, Upton, Long Island, New York
	One of the most expensive components of proposals to accelerate heavy radioactive beams is the superconducting linac. This is an attempt to design a non-scaling Fixed-Field Alternating-Gradient (FFAG) lattice to allow acceleration of heavy radioactive beams in a short time period with an acceptance in momentum of ±50%. As it had been previously reported the non-scaling FFAG has very small orbit offsets, very strong focusing, and large momentum acceptance. The lattice with small combined function magnets would provide substantial savings in the cost of the RF.
TUPLS070	Chromaticity Control in Linear-field Nonscaling FFAGs by Sextapoles	1657
	S.R. Koscielniak TRIUMF, Vancouver
	Because of their high repetition rate and large apertures, FFAGs are proposed for high-current medical accelerators suitable for cancer therapy. The linear-field nonscaling FFAG is made from repeating cells containing D and F combined function magnets. The betatron tune profiles decrease with momentum; this leads to the crossing of resonances. We examine how sextapole magnets may be used to flatten the tune profile; in particular (i) whether it is better to place them at the D or F; (ii) what strength is required; and (iii) what is their effect on the closed orbits and path length? The orbit geometry is derived from a thin-element model and the tunes from power series in the quadrupole strength. Chromaticity is corrected by coupling focusing strength to dispersion, which is far stronger in the F element. The zeros of the orbit dispersion become the poles of the "sextapole strength to flatten the tune at some particular momentum". We demonstrate that a weak F sextapole can produce a substantial horizontal tune flattening, and has little impact on other optical properties. Contrarily, placing the sextapole at the D element may destroy the dynamic aperture and or vertical focusing.
TUPLS071	Minimum Cost Lattices for Nonscaling FFAGs	1660
	S.R. Koscielniak TRIUMF, Vancouver
	Previously, linear-field FFAG lattices for muon acceleration have been optimized under the condition of minimum path length variation. For non-relativistic particles, as are employed in the hadron therapy of cancer, that constraint is removed allowing a wider range of design choices. We adopt the thin-element kick model for a degenerate F0D0 cell composed of D and F combined function magnets. The dipole field components are parametrised in terms of the bending at the reference momentum and the reverse bend angle. The split between positive and negative bending sets the shape of the closed orbits. The cost function, based on stored magnetic energy, is explored in terms of the split. Two cost minima are found, one corresponding to minimum peak magnet field in the F element, and another to minimum radial aperture in the D element. Analytic formulae are given for the minimization conditions. The minimum field lattice is similar to existing designs based on minimizing the path length variation, but the minimum aperture lattice presents a new direction for future detailed design studies.
TUPLS072	Nonscaling FFAG with Equal Longitudinal and Transverse Reference Momenta	1663
	S.R. Koscielniak TRIUMF, Vancouver
	An unusual feature of linear-field nonscaling FFAG designs is that the radio-frequency is not necessarily synchronous with the reference orbit and momentum chosen for the lattice design. This arises because optics design prefers the reference geometry to be composed of straight lines and arcs of circles - either at the mean momentum, or at high momentum to centre the orbit in the F element. The asynchronous acceleration proposed for rapid acceleration has strong requirements to set the longitudinal reference at 1/4 and 3/4 of the momentum range to minimize phase slip. The usual particle-tracking programs, such as MAD, though sophisticated in the transverse plane, are far cruder in their longitudinal working and do not allow for a longitudinal reference momentum and RF phase independent of the transverse values. In the context of a thin-element lattice model, we show how to make the transverse reference momentum and optic design coincident with the longitudinal reference by adjusting the ratio of positive and negative bending in the D and F elements, respectively, and retaining a lines and arcs composition for the reference orbit. This prepares the way for MAD tracking.
TUPLS073	Formulae for Linear-field Non-scaling FFAG Accelerator Orbits	1666
	M.K. Craddock UBC & TRIUMF, Vancouver, British Columbia S.R. Koscielniak TRIUMF, Vancouver
	Non-scaling FFAG accelerators using constant-gradient F and D magnets with their fields decreasing outwards can compact ion orbits for a wide range of momentum (e.g., 1:2) into a narrow radial range. Designs to accelerate protons, ions and muons are currently being studied for proton drivers, cancer therapy facilities and neutrino factories. In this paper, analytic formulae are reported for some basic orbit properties, helping to make clear their dependence on the various design parameters and momentum. For the designs tested so far the numerical results are in excellent agreement with those obtained using lattice codes.
TUPLS075	Design of the Flat-top Acceleration Cavity for the LNS Superconducting Cyclotron	1669
	L.A.C. Piazza, D. Battaglia, L. Calabretta, A.C. Caruso, F. Consoli, M.M. Maggiore, D. Rifuggiato, A. Spartà INFN/LNS, Catania
	A 3rd harmonic Flat-top acceleration system for the K800 Superconducting Cyclotron of the Laboratori Nazionali del Sud (LNS) was designed to reduce the energy spread of the accelerated particles and to improve the beam quality and the extraction efficiency. The Flat-top effect is realized by the superposition of the 3rd harmonic to the fundamental acceleration frequency. The 3rd harmonic frequency is produced by an additional resonator, capacitively coupled to the K 800 cavities. The Flat-top cavity was designed with the 3D electromagnetic codes Ansoft HFSS and CST MicroWaveStudio.
TUPLS076	Beam Extraction of 150 MeV FFAG	1672
	M. Aiba, Y. Mori, H. Nakayama, K. Okabe, Y. Sakamoto, A. Takagi KEK, Ibaraki R. Taki GUAS/AS, Ibaraki Y. Yonemura Kyushu University, Fukuoka
	A beam extraction from FFAG accelerator was performed for the first time at KEK 150MeV proton FFAG synchrotron. The purpose of 150MeV FFAG project is to establish a working prototype for various applications. The beam extraction is thus one of important goals. The extraction is based on fast extraction methode using kicker and pulse septum working at 100Hz. A rapid cycling is also our focus to take advantages of FFAG accelerator. Beam extraction experiment was successful under 100Hz operating. The details of experiment will be presented in this paper.
TUPLS077	Development of FFAG-ERIT Ring	1675
	K. Okabe, M. Muto KEK, Ibaraki Y. Mori KURRI, Osaka
	An intense neutron source with the emittance recovery internal target (ERIT) using the FFAG accelerator is under development. The design of the FFAG storage ring for this purpose will be presented.
TUPLS078	Design Studies of the Compact Superconducting Cyclotron for Hadron Therapy	1678
	Y. Jongen, W. Beeckman, W.J.G.M. Kleeven, D. Vandeplassche, S.E. Zaremba IBA, Louvain-la-Neuve V. Aleksandrov, G.A. Karamysheva, Yu. Kazarinov, I.N. Kian, S.A. Kostromin, N.A. Morozov, E. Samsonov, V. Shevtsov, G. Shirkov, E. Syresin JINR, Dubna, Moscow Region
	An overview of the current status of the design of the compact superconducting isochronous cyclotron C400 able to deliver ion beams with a charge to mass ratio of 0.5 is given. This cyclotron is based on the design of the current PT (proton therapy) C230 cyclotron and will be used for radiotherapy with proton, helium or carbon ions. 12C⁶⁺ and 4He²⁺ ions will be accelerated to 400 MeV/u energy and extracted by electrostatic deflector, H²⁺ ions will be accelerated to the energy 260MeV and extracted by stripping. Computer modeling results on the axial injection system, magnetic system, inflector and center design are given. Results of simulations of the ion beam injection, acceleration and extraction are presented.
TUPLS079	Hadron Cancer Therapy Complex Employing Non-scaling FFAG Accelerator and Fixed Field Gantry Design	1681
	E. Keil CERN, Geneva A. Sessler LBNL, Berkeley, California D. Trbojevic BNL, Upton, Long Island, New York
	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.