1. Summary of WG 3 (Sources) First ILC Meeting @ KEK K. Floettmann ILC@DESY 2.12.04

2. WG Topics polarized electron source positron source damping ring –kicker bunch compressor

3. Polarized Electron Source no problem with cathodes expected, polarization: 85-90%, Qe = 0.5-1% injector is straight forward Japanese and US-groups see problems with laser, but…

4. OPCPA system for generation of trains of femtosecond pulses with ~800 nm wavelength Output pulse train of the OPCPA OPCPA system generates trains of picosecond or femtosecond pulses  = 150 fs.. 20 ps (FWHM) OPCPA system generates trains of picosecond or femtosecond pulses  = 150 fs.. 20 ps (FWHM) pulse energy: E micro = 50…100  J E train = up to 80 mJ pulse energy: E micro = 50…100  J E train = up to 80 mJ n Available wavelength: = 790…830 nm = 790…830 nm up to 900 us I. Will, H. Redlin, MBI Berlin

5. Pump Probe Laser at TTF not the optimal solution for PES, but in principle working (I. Will has many ideas to do better) Nagoya/KEK try to get money to build a prototype injector, first contacts to MBI

6. Positron Source Conventional, undulator based, Compton backscattering ??? Pre-damping ring required for the conventional source –some proponents think it can be avoided (increased acceptance of the DR) –others think a pre-damping ring is required also for the undulator based source (too small acceptance of the DR)

7. Positron Source (cont’d) Discussion on reliability and operational issues –so far only known arguments –input required => EuroTEV –neutron production is an important topic –anyone willing to work on it (I can give some input)??? FNAL/ANL work on beam dynamics, experiments proposed

8. Damping Ring 17, 6, 3 km ?? Choice of design (for CDR?) will need to be based on: –achievable performance from kickers (and other technical subsystems) Kickers are easier in longer lattices. –beam dynamics Some effects are worse in longer lattices (e.g. space charge) Some effects are worse in shorter lattices (e.g. electron cloud) Some effects don’t scale easily (e.g. resistive wall instability) –operational flexibility Longer lattices are generally better –costs

9. Damping Ring everybody likes shorter rings, but advantages are not so obvious many groups working on DR, many proposals, but how to compare? wiggler effects seem to be well understood may possibilities for experimental work

10. New dogbone lattice by A. Wolski

11. Kickers no break through, but some interesting ideas for technical details (shock line, crab cavity in bypass…) growing R&D activities

12. Bunch Compression two stage or single stage proposals with and without 3 rd harmonic system synergy with FEL ??? –microbunching instability and CSR probably no problem, but how about spikes? –diagnostics