Updates on gun simulations and detector integration in the chamber

Wednesday 22 Nov 2023, 09:00 → 10:00 Europe/Zurich

354/1-019 (CERN)

CTF2_detector_integration.pdf

CTF2_detector_integration.pptx

will need to reschedule another meeting for detector integration (not time left).

The laser beam profile is donut shape when not at focus (which is what has been looked at so far). To fix, laser can be put in vacuum beam pipe. As it is for the current working point, the laser profile is best approximated to a flat top with a 1 mm radius. To mitigate this, need to scan the focus, and at or near focus, the beam size should be Gaussian. Another option would be to lengthen the pulse length. 

When doing the focus scan, work with a large attenuation, at 8000, and at 1 Hz. Also bring valve down, so that there is no laser beam on the cathode, and we only have the laser on the virtual cathode camera. After identifying a good laser focus, use the electron beam at high attenuation and check the bunch charge. 

For the beam energy, numbers seem reasonable. A further check would be to do the experimental solenoid strength scan at a different energy, say 1 MeV less, and compare with the existing calibration. If the values again match, will redefine the zero length on the spectrometer camera. 

Simulations showed that decreasing the laser pulse length leads to a smaller spot, contrary to expectations. Will need to recheck the simulations.

For more accurate simulations, good to have a 3D field map.