This morning we found the Filter cavity unlocked and strongly misaligned.

When we started the recover procedure and we misaligned the FCEM, we found out that the beam was not in center of FCEB_GR_cam ( Figure 1). In order to recover the position we discharge the correction of the BPC loop using the following procedure:

1. On AFC_Ctrl we turned off Drift controll and BPC controll pushing OFF on VPM interface
2. After that we Discharge the Correction pushing Corr Disable on both the controller (Figure 2)
3. Re-enable the correcion pushing Corr Enable on both the controller
4. Re-enable both the controller

The beam went back in the standard position on FCEB_GR_CAM Figure 3

After that we moved the FCEM at the same posiotion of the begging of the shift and started the prealignment using FCEM and FCIM

Attachment

• Figure 1 Beam position at the FCEB_GR_CAM before
• Figure 2 Discharge of the BPC correction
• Figure 3 Beam position at the FCEB_GR_CAM after
• Figure 4 Trend unlock night (yesterday we left around 1:00 CEST)