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Koscielniak, S. R.

Paper Title Page
TUPAN001 Analytic Models for Quadrupole Fringe-Field Effects 1386
 
  • S. R. Koscielniak
    TRIUMF, Vancouver
  • C. Johnstone
    Fermilab, Batavia, Illinois
 
  Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada

The linear-field non-scaling FFAG lattices originally proposed for multi-GeV muon acceleration are now being modified for application to order 100 MeV/u proton or carbon medical applications. The momentum range is large and the chromatic tune variation is significant. In the medical case, the time of flight variation is immaterial but the issue of resonance crossing is more acute owing to the much lower rate of energy gain. Magnets with non-normal entry/exit faces are considered as means to reduce the tune variation. Thus one is motivated to study fringe fields and their effects. We make a brief study of dipole and quadrupole magnets with normal and rotated entry/exit faces. For the artificial case of a cosine-squared fall off in the quadrupole field, analytic results are obtained which though approximate are superior to numerical integration. This property is achieved by insisting that the error in the equation of motion is zero and the determinant is unity at the entry, exit and centre of the fringe field.

 
TUPAN002 Large Displacement and Divergence Analytic Transfer Maps Through Quadrupoles 1389
 
  • S. R. Koscielniak
    TRIUMF, Vancouver
 
  Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada.

Linear-field non-scaling FFAGs are proposed for multi-GeV muon acceleration and order hundred MeV/u proton or carbon medical applications. The periodic lattices, which have large momentum acceptance (factor >3), employ cells comprised of combined function magnets. In one implementation, rectangular-shaped quadrupoles are used, with the dipole component generated by off-setting the magnet centre. This feature, coupled with the large radial aperture, gives rise to orbits with large displacement and/or divergence from the quadrupole centre. The angles may be so large that there is a partial interchange of longitudinal and radial momenta. We examine two methods to devise maps (through the body field) that are third order in radial coordinate and higher order in momentum. The WKBJ approximation is concluded to be no better than the usual linear transfer matrix. A Green's function approach is carried through to non-linear mappings for the dynamical variables, which are coupled. The first partial derivative of this map (relates to tune variation) produces a linear transfer matrix which must have unity determinant. For the FFAG application, the map is comparable with numerical integration.

 
THPMN103 New Nonscaling FFAG for Medical Applications 2951
 
  • C. Johnstone
    Fermilab, Batavia, Illinois
  • S. R. Koscielniak
    TRIUMF, Vancouver
 
  Funding: Work supported by by the Fermilab Research Association, Inc., under contract DE-AC02-76CH00300 with the U. S. Department of Energy.

Fixed Field Alternating Gradient (FFAG) machines have been the subject of recent international activity due to their potential for medical applications and accelerator-based technologies. In particular, nonscaling FFAGs (where the optics are not constant and therefore do not scale with momentum) stand to offer the high current advantage of the cyclotron combined with the smaller radial aperture of the synchrotron plus variable extraction energy. Here, a hybrid design for a nonscaling FFAG accelerator has been invented which uses both edge and alternating-gradient focusing principles applied to a combined-function magnet applied in a specific configuration to stabilize tunes through an acceleration cycle which extends over a factor of 2-6 in momentum. Using normal conducting magnets, the final, extracted energy from this machine attains 400 MeV/nucleon and a normalized emittance of ~10 - 20π, and thus supports a carbon ion beam in the energy range of interest for cancer therapy.

 
THPMS083 The EMMA Lattice Design 3181
 
  • J. S. Berg, A. G. Ruggiero
    BNL, Upton, Long Island, New York
  • S. R. Koscielniak
    TRIUMF, Vancouver
  • S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
 
  Funding: Work Supported by the United States Department of Energy, Contract No. DE-AC02-98CH10886.

EMMA is a 10 to 20 MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). This paper describes the design of the EMMA lattice. We begin with a description of the experimental goals that impact the lattice design. We then describe what motivated the choice for the basic lattice parameters, such as the type of cells, the number of cells, and the RF frequency. We next list the different configurations that we wish to operate the machine in so as to accomplish our experimental goals. Finally, we enumerate the detailed lattice parameters, showing how these parameters result from the various lattice configurations.

 
THPAN009 Orbit Properties of Non-Scaling FFAG Accelerators Using Constant-Gradient Magnets 3241
 
  • M. K. Craddock
    UBC & TRIUMF, Vancouver, British Columbia
  • S. R. Koscielniak
    TRIUMF, Vancouver
 
  Very high momentum compaction can be obtained in non-scaling FFAG accelerators using constant-gradient magnets with their field strengths decreasing outwards - sufficiently high that the magnet apertures (and vacuum chamber) need be little wider than in a strong-focusing synchrotron. Such machines are of great potential interest for applications in the 0.1 - 50 GeV energy range requiring higher intensities or pulse repetition rates than synchrotrons can provide. Analytic formulae have been developed for the basic orbit properties, particularly their momentum dependence, in various lattices, and give accurate enough results to provide a useful tool for choosing the magnet parameters. In this paper the dependences of orbit offset and circumference on momentum are explored for doublet lattices, and numerical results from the formulae are compared with those from lattice codes.