Virgo Logbook

Virgo Runs (ER13)

Gherardini - 23:01 Sunday 16 December 2018 (44089)

Operator report - afternoon shift 16/12

This afternoon we had a lot o trouble to keep the itf locked; after the intervention on the PR suspension I and Ettore spent a lot o time to recover the alignment of the north cavity, at the beginning we tried to have a good alignment moving the mirror around the position of the last lock, at the end we succeeded moving a lot the vertical position of the PR mirror that is changed by ~120nm (see 1st plot); finally at around 16:50utc after that and a period of crisis of the injection system or maybe something coming from the SSFS? we reached again LOW_NOISE_3 state with the usual horizon of ~44Mpc; but just for few minutes then it was no more possible lock because of problem with the SSFS, Julia and Alain worked from remote to solve the problem and the itf was relocked in LOW_NOISE_3 state at 18:40utc.
At 21:29utc the itf unlocked again because of injection-unlock/SSFS (2nd plot), now we are trying to relock with some difficulties, the weather condition get worse during the day with wind and rain and now the wind is really strong...

-inj
the PSL_AMP_DIODE_3_TEMP is slightly increasing over its threshold (3nd plot)

OnCall events
- SAT PR vertical coil saturation
- ISC locking problem due to SSFS (44086) completed at ~19:00utc

-guard tour(utc)
16:25 - 17:05
18:25 - 19:00
20:50 - 21:25

Images attached to this report

44089_20181216230036_20181216224432meanpslampdiode3temp30.png

Comments to this report:

majorana - 7:31 Monday 17 December 2018 (44091)

Indeed, a relatively simple action (reduction of high DC voltage on the V control, usually 30 min), took a much longer recovery time due to a mistake (by me). This occurrence will drive the design of automated procedure to be dealt by operators.

ruggi - 11:02 Monday 17 December 2018 (44092)

Just to be more precise, I show the signal which should measure the vertical position of PR mirror. It is not in the data: it is computed adding Sc_PR_F7_Y (vertical position of F7) and Sa_PR_F7_LVDT_V multipied by 2 (vertical displacement of the last stage; the factor of 2 is there to compensate a wrong calibration, which is anyway quite uncertain). In fact, after the manual recovery and a slow adjustment of ITF loops, the residual jump was 40 microns. This is not explained, but not huge; it should not determine a relevant change in the ITF working point.

Images attached to this comment