The goal of the shift was to check the relative position of the NI RH (i.e. the center of the NI mirror) and the NI CH induced curvature centers, to check the alignment of the NI CO2 actuators on the NI test mass, following yesterday's activity (56621).

The activity from morning shift proceeded along afternoon (and indeed until night, 56631) and we did not manage to recover the same configuration of yesterday’s measurement for NI RH (that is, cavities locked and then NI single bounce). So we decided to proceed with the ITF in the configuration with N arm locked and W arm unlocked.

After checking the HWS DET illumination, at 16.36 UTC the HWS DET acquisition was started and at 16.45 UTC the NI CH was switched ON at high power. Differently from yesterday’s measurement and as expected, the induced curvature appeared immediately after (see fig.1) and the center position stabilized around 20 minutes after, so at 17.09 UTC the NI CH was blocked on the bench by the flip mirror.

A comparison with respect to yesterday’s NI RH center position is shown in table 1

Trying to move the NI CH along horizontal direction through NI picomotors, I noticed that the TCSPicoW/NI was not responding. So around 18.20 UTC I went to the TCS room to restart the corresponding drivers: the action worked and the TCSPicoW/NI actuators got back online.

At 18.35 UTC a movement of around 2 cm along horizontal direction was performed and at 18.40 UTC the NI CH was switched ON again. The curvature appeared again immediately after, the results are summarized in table 2. The NI CH was again blocked on the bench at 19.08 UTC.

Before doing any further movement, we agreed on checking the NI RH center in today’s configuration, so at 19.47 UTC the NI RH was switched ON @15W. After almost 1 hour and half the position was stable (result is shown in table 3) and the NI RH was switched OFF at 21.20 UTC.

The NI RH was in a different position with respect to the day before and another horizontal movement is still needed (see fig.2): I performed it at 22.28 UTC, it should be checked in the next shifts.

At the end of the shift, as requested durign Daily meeting:

• at 21.30 UTC I changed the CHRoCC voltage to 0.43 V (corresponding to almost 0.8 W)

• at 21.31 UTC I switched ON the SR RH at nominal power, that is 7 W

• at 21.40 UTC I switched ON the NI DASes at nominal powers to compensate NI CP cold lens (see entry 56602)