Takano, Fujimoto, Tanaka, Dan

Summary

We performed the initial alignment of the IFO by following the procedure in klog36759. After that, we tried to find the SRC flash by shaking SRM and moving SRM IP in yaw direction. Finally, we observed clear SRC flashes.

What we did

Initial alignment of IFO

First, we performed the initial alignment of the IFO. Since the transmissivity of SRM was changed, the usual initial alignment procedure cannot be used for the AS side alignment. Therefore, we adjusted the alignment by referring to klog36759.

For X-arm and Y-arm, we used the usual initial alignment procedure. After that, we continued the alignment according to the procedure described in klog36759. As written in the klog, we moved OMMT1 while monitoring OMMT1_TRAS_QPD1. When the beam position on OMMT1_TRAS_QPD1 became almost centered, we regarded the AS side alignment as good.

Search for SRC flash

Next, we tried to find the SRC flash by adjusting the alignment of SRM. We set only ITMY to LOCK_ACQUISITION and misaligned the other Type-A suspensions. We also restored the SRM IM OPTICALIGN pitch value to yesterday’s value of 3825. In this condition, we largely moved only the yaw alignment of SRM. We used the stepping motor and moved SRM IP F0_Y from about -12073 to -27073. Then the flash could be seen. After that, we continued the alignment while monitoring the flash signal. Finally, we found good SRC flashes with the following SRM IM OPTICALIGN values:

• P: 3900
• Y: 480

The flash signal was monitored with K1:LSC-POS_PPOL_DC_OUT_DQ. This is the signal from the temporary PD installed yesterday on the POS table, and the flash appeared clearly in this channel.

However, since the suspension was still oscillating, it was difficult to further optimize the alignment at this moment.

Next, we entered the mine, center the QPDs, and try to turn on the local controls.