Preliminary Idea of IP feedback and Basic Questions
Two IPBPMs can be installed in IP chamber. Each IPBPM has 2 cavities, one of which (IPBPM-2,3) is 79.2mm from the IP and the second one(IPBPM-1,4) is 81mm from the first one. Sequential number of IPBPM-cavities is ordered from the upstream. Shintake monitor has interference pattern at IP.
One possibility is to use IPBPM-2 for input to the FONT and we can reconstruct beam orbits with positions at the other 3 cavities ( IPBPM-1, -3 and -4) . These IPBPMs are low-Q type cavity monitors for the FONT.
First, following items should be studied for feasibility of this possibility;
- sensitivity of beam-offset at the IPBPM-2 and at the IP
We have assumed the IPBPM resolution of 2nm at IP for the feedback.
Is the same resolution needed at the IPBPM-2 ?
- How much resolution of the IPBPM-1, -3 and -4 is needed to monitor the nanometer stabilization at IP ?
- How does angular jitter effect on the feedback performance ?
- Does the FONT require signals also from the other cavities ?