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Update on ILC ML Lattice Design

Update on ILC ML Lattice Design. Alexander Valishev, for the FNAL LET group FNAL AP Dept. Meeting March 7, 2007. Outline. Basic layout Curvature implementation Matching Summary and problems. Lattice Design. Defined by cryo segmentation Versions of segmentation

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Update on ILC ML Lattice Design

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  1. Update on ILC ML Lattice Design Alexander Valishev, for the FNAL LET group FNAL AP Dept. Meeting March 7, 2007

  2. Outline • Basic layout • Curvature implementation • Matching • Summary and problems

  3. Lattice Design • Defined by cryo segmentation • Versions of segmentation • 8-8-8 scheme, Nov 21 2006 • 9-8-9 scheme, Dec 28 2006 • Basic segmentations: RF Unit Cryogenic Unit Main Linac

  4. Nov. 21 revision (v.4) 8-8-8

  5. Lattice Revision History *) http://tdserver1.fnal.gov/project/ILC/ARCHIVE/ILC-ML-SbendCurvature.zip **) http://www.slac.stanford.edu/~mdw/ILC/2006e/

  6. Curvature Implementation • Beam line geometry definition differs for MatLIAR/Lucretia and MAD. • A method to have one set of decks and still be able to work with two codes was proposed by M.Woodley: • One common XSIF file, defining beam line, all common elements, and ‘KINK’ elements at the ends of cryomodules. • Two different files defining KINK elements to be used in MatLIAR and MAD. One of the files is called from the main file depending on the software used. • Beam trajectory in both cases is changed by VKICK elements • Another approach is to use vertical SBENDs • In this case one deck is compatible with both codes

  7. Curvature Implementation • GKICK, Multipole • SBEND

  8. Implementation of ‘KINKs’ • MatLIAR/Lucretia: Thin ‘dispersion-free kick’ GKICK, which pitches the coordinate system. • MAD: Combination of • General thin multipole n=0, changes both the beam trajectory and the coordinate system • VKICK of the opposite sign

  9. ILC2006e (8-8-8) Lattice b-functions LIAR MAD Lucretia

  10. ILC2006e Orbit MAD Lucretia

  11. ILC2006e Dispersion MAD Lucretia

  12. Emittance Preservation Zoom Mean: 5.3 ± 0.5 nm Orbit at the YCORs (mm) Normalized Emittance (nm) 90%: 9.5 nm Curved Mean: 5.0 ± 0.4 nm 90%: 8.7 nm Laser Straight • LIAR Simulation: CURVED LINAC: ILC BCD-Like LATTICE Perfect Lattice - No misalignments BPM index • Static Tuning: Dispersion Matched Steering (DMS) - Misalign the beamline components and perform the steering Distribution of emittance growth for 50 seeds Average of 50 machines Curved Corrected normalized emittance (nm) Straight BPM index

  13. Summary • ML lattices based on two cryogenic layouts have been developed • Two versions of ILC2006e (8-8-8) ML lattice (GKICK/MULT and SBEND) were studied • Both versions work well in Lucretia and show similar emittance growth • It was decided at the Daresbury meeting in January that only GKICK/MULT lattice will be supported • Static alignment simulations show acceptable emittance growth in the curved ML lattice • Dynamic simulations in progress

  14. TODO • Create set of decks suitable for simulations of bunch propagation from RTML to the end • Improve dispersion matching between curved and straight sections • The way it was implemented in ILC2006e suggests large orbit kinks with angles of ~3e-4. At 250 GeV, this leads to energy losses of 100MeV and synchrotron radiation power of 4kW • Angle of steering to the Earth’s curvature is 6e-6. Eloss=37keV, Ploss=1.6W • One possible solution – make smooth transition from curved to straight beam line.

  15. Synchrotron Radiation in a Single Corrector E – particle energy [GeV] a – bending angle L – corrector length [m] B – corrector field [T] E=250 L=0.335 Iav=4e-5 for 1ms beam at 5Hz USR – particle energy loss [eV] Iav – average beam current [A] PSR – average radiated power [W]

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