Author: Montgomery, D.T.
Paper Title Page
TUPSH009 Magnetic Field Mapping of the Best 70 MeV Cyclotron 239
  • F.S. Grillet, B.F. Milton
    BCSI, Vancouver, BC, Canada
  • D.T. Montgomery
    Cedarflat Precision Inc., Burnaby, British Columbia, Canada
  As is well known, the mapping of a cyclotron magnet presents several key challenges including requirements for a high degree of accuracy and difficult space constraints in the region to be measured. Several novel solutions were used to create the mapper for the Best 70 MeV cyclotron, which is based on an earlier version used to map the Best 14 MeV cyclotron. Based on a temperature compensated 3-Axis hall probe that is continuously sampled while the probe travels along a radial arm a high degree of positional accuracy is achieved by simultaneously sampling optical encoders located with the probe. A novel implementation using air bearings and air jets provides axial rotation of the arm with almost no metal parts. The mapper has achieved a full 360 degree map in 1 degree theta steps, and 2.5mm radial steps in 2 hours and 40 minutes, with a relative radial accuracy of ±0.02mm and angular accuracy of ±0.001 degrees. This paper will describe how the simultaneous challenges of designing with no metal parts while achieving a high degree of rigidity and precision have been addressed.