Update on ILC ML Lattice Design

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]