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 Dejans Gantry NS-FFAG gantry: superconducting transmits MeV/u but requires two current settings dispersion is very small throughout lattice -5mm +10mm p/p 15% Dejans 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 cant 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