Clipping issue: prism and e-beam
At the beginning of the access the green laser was aligned to the electron beam vector. The prism used to image the focal spot / CeYAG screen clipped the green laser:
To avoid this, we moved the prism such that the green laser (later electron beam) can safely pass the edge of the prism (for imaging the CeYAG scintillation light produced by the electron beam).