[Yokozawa, Chen, Hirose]
We performed initial alignment procedures.
The X-arm, Y-arm, and OMC alignments were completed. We also tried to align SRY, but it could not be completed.
There was an earthquake just before starting the work, followed by some aftershocks. The ground motion was relatively large today, and this likely made the SRY lock difficult.
Details will be reported later.
Just before starting the work, an earthquake occurred. There were also some aftershocks during the work. The earthquake was likely around seismic intensity 3 near Niigata. In addition, the ground motion was relatively large today.
As a preparation, we misaligned SRM and PRM to avoid unwanted resonances. We also confirmed that all Type-A suspensions could go to the LOCK_ACQUISITION state.
The GRX and GRY shutters were opened. The GR transmission was about 0.7 for X-arm and about 1 for Y-arm.
An aftershock occurred at around 06:09.
Before starting the guardian-based initial alignment, we slightly moved PR3 to increase the GRX transmission.
The PR3 opticalign values were adjusted to increase the GRX transmission.
After that, we requested IRX_LOCKED. Then we requested GRX_LOCKED_WITH_IRX, but the lock was lost. The IMC did not recover automatically, so we worked on the IO alignment.
We requested PROVIDING_STABLE_LIGHT in the IO guardian and adjusted the PZTs. For example, we changed the PZT1 pitch offset. The original value was 75, and we tried 102 because the corresponding input value was about 27 when the alignment was good. We looked for sudden changes and tried to bring the corresponding degrees of freedom back to the previous good values.
We adjusted by using PZT{1,2}_{P,Y}. After recovering the IMC lock, we waited for the ASC to engage. Finally, the PZT value was returned to 75.
After the IO was recovered, we continued the X-arm alignment using the initial alignment guardian. In the ALIGNING_XARM state, we manually moved ITMX and ETMX while checking the transmission. And completed the Xarm alignment.
We then started the Y-arm alignment. During the Y-arm alignment, we slightly moved BS to improve the alignment.
For the OMC alignment, we first turned off the GR beams and requested IRY_LOCKED_FOR_OMC. Then we requested ENGAGE_OMMT2_TRANS_CENTERING, followed by ALIGNING_TO_OMC.
During the alignment, K1:OMC_TRANS_DC_SUM_OUT16 increased to about 33 and became stable. The alignment became stable, although the change was not very large.
After that, we requested RECORD_GOOD_VALUES_OMC.
Finally, we tried the SRY alignment. We requested ALIGNING_SEY and adjusted SRM, referring to the procedure in klog 36967.
Since the alignment did not look good, we set the guardian to DOWN and manually moved SRM. We adjusted SRM while watching K1:LSC-AS_PDA1_DC_OUT_DQ and the POP camera.
We then requested ALIGNING_SRY again and adjusted the SRM opticalign values so that the oplev values became close to the previous good oplev values. We tried ALIGNING_SRY once more, but SRY could not be locked.
The failure to complete the SRY alignment might have been due to the relatively large ground motion today, including the earthquake and aftershocks.
The X-arm, Y-arm, and OMC alignments were completed. We also tried the SRY alignment, but it could not be completed.