Overview of final concept cavity gun Bunch compressor

Overview of final* concept cavity gun Bunch compressor 3. 9 GHz 45 deg. spectro 3 ILC cryomodules 18 4 57 ~10 61 injector * as of last week version main linac user area transport line dis p. are a

ILCTA layout • Injector: • rf-gun • TESLA high gradient accelerating cavity • Bunch compressor, • Eventually: • 3 rd harmonic cavity (f=3. 9 GHz) • Dog-leg + deflecting mode cavity • Main linac: • Eventually 3 ILC-type modules • Initially one module • Transport line • Focusing/steering elements, • Standard diagnostics (screens + BPM) • Area for diagnostics and/or accelerator physics experiment requiring multi-bunches • Initially transport line will be long (when only one ILC module) • Dispersive area • Diagnostics (energy + energy spread measurement) • “User” area • “Free” beamline for advanced accelerator and diagnostics R&D only single bunch mode operation possible (low power)

Optimization of a short injector (E cathode = 40 MV/m, Q=3. 2 n. C) • Objective: “minimize emittance” at 8 m from cathode (assume round beam and do not include matching section) • Free parameters: laser spot size, gun phase, solenoid fields, E-field and location of SCRF cavity parameter value slaser (mm) 2. 04 fgun (deg) 15 B 1 (T) 0. 150 B 2 (T) 0. 155 Epeak (MV/m) 30. 6 zcav (m) 1. 85

Optimization of a short injector (E cathode = 40 MV/m) K=20. 4 Me. V

Injector 14 m gun cavity 3. 9 GHz TM 010 BPM ICT Ya. G quadrupole OTR BPM OTR Slit(s) OTR ICT dipole Bunch compressor OTR BPM OTR Ya. G/OTR Slit(s) OTR/CTR ICT Streak camera port skew quadrupole 3. 9 GHz TM 110 BPM OTR

Injector length needed; reusing A 0 components 2. 736 m Real-estate needed: Distances were provided by B. Popper (SMTF injector phase A drawing of Dec. 21 st, 2005) • Cavity center is 1. 85 m from cath. (Astra sim. ) • 3. 9 Ghz exit at 1. 85+2. 736= 4. 586 m • Entrance of module should be at 4. 586+6. 537=11. 123 m ~ 11. 5 m from cath. • round-to-flat beam transform: + 1 meters • HOM dogleg: +1 meter • SO TOTAL INJECTOR LENGTH is ~12. 5 m • Reuses A 0 quads -- not sure about steerers Typical DESY assembly everything is welded (includes: 1 ICT, 2 sixways X’s +1 BPM chamber) 6. 537 m

Transport section (straight ahead)

Compression Performance (1 n. C example)

Compression Performance (1 n. C example) Peak current at 1 n. C: 2 k. A!

Dogleg and off-axis beamline • Double bend achromat to offset the beam in an off-axis dispersionless beamline • R 56 should be small to avoid influencing the bunch length • Bending angle + effective length of dipole (=curvature radius) still need to be chosen; right now 22. 5 deg, Leff=0. 3 m (current offset if 1 m)

Diagnostics using the DMC Cavity OFF Eta=0 Beam spot on FDL 3 for various scenario: Cavity ON: cavity vertically deflecting Eta NOT 0: dispersion leak in the horizontal plane. Cavity on Eta=0 Cavity on Eta NOT 0

ILC Module + post module lattice Disp. Section ILC module chain III+ Spectr. IV+ dump Lattice rev. AUG-06 -2006

Can be used as an AARD facility 45 deg. spectro Bunch cavity High Energy bunch compressor gun 3. 9 GHz 3 ILC cryomodules experimental area: could have 3 parallel beamline • Example with 1 st module at ~ 18 m • Two stage bunch compression should allow peak current of ~5 k. A • High energy bunch compressor followed by cavity operated a zero-crossing to remove correlated energy spread • In principle this layout has comparable performance to state-of-art linac-driver for short wavelength SASE free-electron lasers

Summary & on-going work • Finally all parties agreed on a possible layout at ILCTA • Preliminary “look at” indicate no show stopper • Layout fit building, • Head room for upgrade (e. g. new gun location) • Immediate work if focused on ILC-type applications, and simulation of related experiment (e. g. wakefield studies will be performed) • The facility is “good-enough” to support an advanced R&D program • First parasitically to ILC-related studies • Then dedicated to AARD with addition of new hall…