PEM team worked around the IXC rack, but we didn't enter the IXC clean area.

• It was found that the SUM_OUT had been decreased for a few months, as the attachment shows.
• Replacing the light source might improve this situation..

I changed whitening chassis for Length-sensing OpLev of ITMX to judge this noisy spectrum comes from whitening chassis or not.
However noisy spectrum was same with before changing chassis. I backed chassis to original assignment.

Thanks to Akutsu-san and his company,

Concerning the oplev issue reported in klog#9681, klog#9855 and so on;

• It was found that the noise level at about 1 to 7Hz was improved by modifying the air-shield structure (Figure 1).
  • It seems so far there was some small hoels on the structure, and they were covered in this time.
  • A quick test was done this time.
• Building a better air-shielding system again is necessary, as the first step. Doing that could improve the noise level more. to be investigated (figure2, after the work, with smaller band width).

Hmm... unfortunately it would be a fake "improvement".

I reinforced the wind shield at around 6:00 UTC (15:00 JST), but comparing those spectra taken at 5:00 UTC (Fig 1) and 7:00 UTC (Fig 2), there are no big changes. Actually no changes with respect to what Fujii-kun reported this early morning (9864).

In 9877, when Fujii-kun took the "ITMX TM-L oplev (before doing it)", I would be walking around the oplev setup (QPD side)...

Anyway, let's see what will happen when the ITMX will get warmer. At the timing I did the work described above, the inside of the IXC chamber was still so shining in green!