Odds and Ends on Gantries Rob Edgecock & Akram Kahn Neither of us knew much about gantries ~1 week ago Neither of us know much about gantries now Will concentrate on carbon Most information comes from CERN PIMMS report (2000) Huge topic, only a few items discussed here! Comments:

Layout HIT Heidelberg Proton-Ion Medical Machine Study (PIMMS) CERN

Requirements Beam delivery from any angle by - rotating gantry - rotating and translating patient table Spot, raster, etc, scanning in 3D - depth from energy - other 2 dimensions: fast scanning magnets

Requirements Minimum size and cost Beam requirements: PIMMSGSI/HIT Ion speciesP, He, C, O Range (cm)3.5 to to 30.0 C energy (MeV/u) Spot distributionGaussian perp to scan Rectangular parallel Spot size variation (mm, FWHM) 4-10 Ions/spill4x10 8 to 4x10 9 1x10 6 to 4x10 10 Scan area20cm by 20cm

Requirements Beam optics independent of gantry position, so  no change in spot size or shape at tumour  no correlation between position and momentum  no change in beam optics in gantry Far from trivial NB  Beam preparation starts in (last) ring  Matching ring  extraction line  gantry v. important  For optimal design (i.e. minimal cost) ring design should take into account extraction line and gantry requirements

Types of Gantry Iso-centric IBA (proton) gantry

Types of Gantry Iso-centric HIT gantry Total weight: 570t Beam components: 140t

Types of Gantry Exo-centric PSI gantry Reduces gantry radius to 2m (cf ~5m, typically)

Types of Gantry Exo-centric PIMMS (Riesenrad) gantry Half the size Third the power Easier to align More space around patient

3D Spot, etc, Scanning “Slowest” dimension: depth, by energy  use planes, starting with deepest  scan plane, reduce energy, scan plane, etc

3D Spot, etc, Scanning Two methods for scanning in plane:

3D Spot, etc, Scanning Two possibilities for scanning magnet positions In gantry optics After last gantry magnet Pros: Parallel beams Smaller apertures (esp. last dipole) 1 scan magnet/plane Cons:Bigger apertures Divergent beam Bigger cost2 scan magnets/plane

Dejan’s Gantry NS-FFAG gantry:  superconducting  transmits MeV/u  but requires two current settings  dispersion is “very small” throughout lattice -5mm +10mm  p/p ±15%

Dejan’s Gantry

 p/p = ±15% orbit offsets x cells Scan: SC magnets 20m long 1.4kg vs 135t Hard to know what to conclude! Tracked with PTC – but can’t compare with requirements More detailed tracking required

Conclusions Gantries (+ extraction line) very important Also, very interesting! Cannot really be ignored in a PAMELA DS E.g. in PIMMS report, different lattice choice for passive spreading and scanning Any idea that reduces size and cost is helpful  Exo-centric  FFAG  etc