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MIF (General)
lucia.trozzo - 13:16 Wednesday 18 December 2019 (12210) Print this report
Recovery of the IFO after several unlocks during this mornig

[Akutsu, Miyoki, Yamada, Lucia]

At  8:44 the IFO unlocked and we tried to recover it.

Here some details of the works.


First we requested to LSC_LOCK guardian to go in Observation state and we succeded to lock the IFO.

Few minutes later, we noticed a degradation of the dark fringe (AS_camera), so we decided to start the alignment procedure by using the "monky" medm. At some point, during the alignment of Xarm, a strange jump in green and IR power occured and the Xarm guardian got crazy, annihiling our alignement trials.

At the end we recovered the good alignement of X green only by tweeking by hand the position of PR3.

We also excuted the alignement procedure for Yarm and in this case we succeded to align it and to lock the FPMI with guardian, but continuously unlocks occured.

At each unlock we observed that:

- Dark fringe has degradeted

- BS sligthly oscillated in PITCH

- ETMY started to oscillate (maybe because of degradation of the alignement).

We tried to align the ETMY by using the procedure reported in klog 12179, but when we requested ENGAGE_ADS the interferometer unlocked, because in the guardian there is not direct connection from OBSERVATION to ENGAGE_ADS.

So we restarted again the lock acquisition and we stoped at ENGAGE_ADS, monitoring the power at AS port. Since the value of the AS port power was around 100 we moved in OBSERVATION state without tweeking EY.

Few minutes later the alignment worsened and IFO unlocked. Before to start the lock acquisition we waited a bit to let the mirrors calm down and we excuted step by step these GUARDIAN states:


-ENGAGE_ADS ( we tweeked a bit EY position in P)

-ENGAGE_ASC (we waited 10 minutes before to move to OBSERVATION)


The FPMI is back in OBSERVATION state from 30 minutes.

Some notes:

-Today the microseimic noise is quite large: this could be a reason of the frequent unlocks.
- To speed up the EY tweeking when the IFO got misaligned it would be useful to add a direct path from OBSERVATION state to ENGAGE_ADS in guardian.

- A check of the X arm guardian should be done.

Comments to this report:
tomotada.akutsu - 18:29 Wednesday 18 December 2019 (12212) Print this report

The attached photo was taken at 14:42 today (18 Dec, JST). Instanteneously the GreenX could reach around 0.8, so the alignment would be one of the keys...

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