1. Why are cylindrical beam profiles required for PWFA’s?
Emittance mixing owing to horizontal/vertical coupling of focusing fields forces symmetric emittance. IP does not need to be cylindrical with asymmetric final focus.
2. Why do the collision and interaction points need to be so close together for photon colliders from e−?
Photons follow the direction of the electrons (e-beam). So scattering must be after the final focus lens. Small spot requires a short beta-function and so scattering must be done near IP.
3. What are the parameters that one can reach for the parameters in Eq in the attachment for photon colliders? Also what are the important parameters that we should be benchmarking when it comes to considering these types of accelerators versus the conventional approaches? Or equivalently, what is currently your best guess of what the energy profile of a gamma collider may be?
This needs more discussion/study. Is this question, what is the luminosity energy spectrum?
We can convert 1 e ~ 1 photon at the target energy.
4. We found a lot of photon collider papers by Telnov. Is he a reliable source in this community?
Telnov was a strong (and lone) advocate of photon colliders 3 decades ago. I think he is reliable; however the parameter regime is significantly different here and his analysis needs to be revisited.
