1. Awake electron beam requirements ParameterBaseline Phase 2Range to check Beam Energy16 MeV10- 20 MeV Energy spread (  ) 0.5 %< 0.5 % ? Bunch Length (  ) 4 ps0.3-10 ps Beam Focus Size (  ) 250  m 0.25 – 1mm Normalized Emittance (rms)2 mm mmrad0.5 - 5 mm mrad Bunch Charge0.2 nC0.1 - 1 nC Let’s assume gaussian or truncated gaussian distributions for transverse phase space for time being For the longitudinal we will simulate gaussian and somewhat more uniform distribution depending what we can expect from the laser

2. Laser requirements 50 mJ 500  J

3. Laser update  We still assume using copper cathodes  Prefer a solution where Amplitude delivers a UV laser beam This means they take care of the compression and the 3 rd harmonic generation. CERN would then transport the UV to the gun and cathode.  UV pulse required: Wavelength: 262 nm; 500 uJ pulse energy and a FWHM pulse length of 10 ps. This pulse would guarantee the base line parameters and the 1 nC option.  For the short pulse 0.3 ps we would need only 50 uJ in the UV assuming that we would have to produce only 0.1 nC of charge (limited by ablation)  Pulse compression independent from the one for the proton beam Independent pulse picker allowing to use only some pulses out of the 10 Hz rep. rate.  The specification for an IR beam would be a pulse energy of 50 mJ. We will still try to investigate the space constraints and keep the option to use different cathodes.

4. Electron source layout

5. Laser table needs to be integrated as well

6. Electron source layout Comments:  Layout is advancing  Some conflicts with the overall length  Need to optimise cathode accelerating structure distance  Need to specify quadrupoles  Study cathode loading system options  Study shielding design and layout

7. Electron source design Oznur Mete, Cockcroft

8. Starting points for calculations  Proton line: the top mirror in vacuum before the laser core tunnel  Electron line: intersection of the “electron” laser beam with the vertical plane formed by 2 vacuum mirrors for “proton” beam 727 98 Valentine and Mikhail

9. 7387 320 1188 vertica l 19929 7387+1188+320+19929 = 28824 mm Proton line: path to plasma cell

10. Electron line: path to photocathode 9846 1087 vertical 1320 500817 Optical table 1000x1800 9846+1087+1320+500+817 = 13570 mm

11. Electron beam path from photocathode to plasma cell 4627 377 3683 736 1536 4319 4627+377*4+3683+736+1536+4319 = 16409 mm

12. Summary  Proton line path to plasma cell = 28824 mm Electron line: laser path + electron path = 29979 mm difference = - 1155 mm is to be compensated by delaying the “proton” pulse (could it exist in the main amplifier ?) Delays due to compressor, THG, UV stretcher, telescope, are not counted! A variable delay of 0 - 200 mm in the electron line is required