The ILC accelerator parameters and detector concepts are still under discussion in the world-wide community. As will be shown, the performance of the BeamCal, the calorimeter in the very forward area of the ILC detector, is very sensitive to the beam parameter and crossing angle choices. We propose here BeamCal designs for small (0 or 2 mrad) and large (20 mrad) crossing angles and report about the veto performance study done. As an illustration, the influence of several proposed beam parameter sets and crossing angles on the signal-to-background ratio in the stau search is estimated for a particular realization of the supersymmetric model.

An overview is given on the test-beam programs to perform detector and system studies for luminosity and energy measurements and beam diagnostics for luminosity optimization.