KAGRA Logbook

DetChar (General)

hirotaka.yuzurihara - 23:46 Sunday 27 February 2022 (19906)

Cont. : Investigation of behavior of GreenX during 2/14(Mon.)

This is a continuation of previous work (klog#19859).

I performed the Hveto again, by considering several comments from Ushiba-san and Akutsh-san.

Here are the updates.

* I added the channels related Green laser control and PR3 oplev. For the used channel list, please check here. The unsafe-channels are channels that are considered to be correlated and have been removed from this analysis.

* From the Hveto result, the channel (K1:IMC-SERVO_MIXER_DAQ_OUT_DQ) was the round winner which is the most coincident channel with the lock loss of GreenX.

* As a quick check, glitches on K1:IMC-SERVO_MIXER_DAQ_OUT_DQ happened earlier than glitch on GreenX (K1:TMS-X_GR_PDA1_OUT_DQ). These were done by checking the glitch time obtained by Omicron. But, this time seems to have an uncertainty. We should confirm this by the other reliable way.

Comments to this report:

hirotaka.yuzurihara - 23:50 Sunday 27 February 2022 (19907)

During this work, I found that the button of Export to CSV which is located in the bottom of the page. If this function works, it will be convenient...

takahiro.yamamoto - 13:53 Monday 28 February 2022 (19916)

MIXER_DAQ_OUT_DQ is applied 21dB whitening gain at the universal whitening filter chassis.
On the other hand, 3 stages of z10;p1 filters are applied as the digital dewhitening filter.

So it may be better to take into account of the phase delay effect due to the mismatch of whitening-dewhitening
in order to compare the timing of glitch occurrence time in accurately.

MIXER_DAQ is just a monitor channel on the digital system and there is no problem for the IMC control and the calibration of MCL.
We may have to fix de-whitening filters as a proper ones for such kind of analysis...

According to my past klog (klog#16823), 21dB gain is required to avoid the ADC noise limit.
So -21dB should be set as a dewhitening filter, if we want to compensate also the overall gain.