The following report has been submitted to the On-call interface.
On-call events -> Interferometer Sensing & Control
Title: Unstable ITF
Author(s): casanueva
| Called at: 09:58, 13-07-2025, by: Montanari |
| Remote intervention: Started: 11:00, 13-07-2025; Ended: 12:00, 13-07-2025 |
| On-site intervention: Started: ; Ended: |
| Status: Unresolved |
| Operator when issue resolved: Montanari |
Details:
This morning the interferometer locked once but once it unlocked it doesn't manage to lock again. Same pattern as yesterday. Looking more closely the difference between today's lock acquisition and three days ago, the only thing that strikes me is that the DIFFp servo behaves completely different during the timer of CARM NULL 1F (Figures 1 and 2).
Something simialr happened already a couple of weeks ago (#67170), and I remember that a long time ago we used this behaviour of the DIFFp servo to fine tune the CH powers, to minimize the thermal transient. I am wondering if the external temperature drop can have pushed the ITF into a slighlty different state so that the CH needs to be readjusted to minimize the transient. To be better understood.
* Note that any files attached to this report are available in the On-call interface.
