Marc and Yuhang

An earthquake happened around 23:48 16/03/2022 JST with earthquake center located at Miyagi/Fukushima Ken (M7.3). The earthquake in Tokyo was observed to be M3.

A check of suspended mirror coil-magnet actuators is necessary. The check relies on the use of coil-magnet actuators and oplev. Since earthquake caused mirror motion change, we need to check firstly if the suspension is still around the nominal positon relative to oplev. If not, we need to bring mirror back to the nominal positon relative to oplev so that we can use oplev to do the further check of coil-magnet actuator.

The PR oplev was found to be still good for oplev. However, Input oplev's laser beam is completely out of PSD as shown in the first attached photo. End oplev's laser beam is in PSD, but it was too far from PSD center. BS oplev doesn't work due to the broken PSD.

Therefore, we moved input mirror picomotor to recover its position for oplev. We centered end mirror oplev's laser beam as well. During the walk to end station, we check the vacuum level measured at 4 positions from TAMA center, South arm beginning, South arm center until South arm end. All vacuum levels are consistent with nominal values and no strange sound was found for vacuum pumps.

We restarted DGS system to solve the test-time out issue, which prevents us from taking oplev noise spectrum measurement. Although we took snapshot for medm setting, we couldn't recover medm setting afterwards. We suspected that this was caused by the 'diskfull' issue. We should pay attention next time.

After all these work, we ran the automatic code as reported in elog2836. We found weird response for Input H4, End H1, and End H3 as the attached figures 2,3,4. Note that the blue and red curves are reference oplev spectrum. The other two curves (green and brown) have difference spectrum and almost no coherence. Therefore, we suspect Input_H4, End_H1, End_H3 magnets may fall down.