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MIF (ITF Control)
takafumi.ushiba - 22:36 Thursday 24 November 2022 (23023) Print this report
PRX/Y and PRMI recovery

I checked PRX and PRMI can be locked or not by guardian.
PRX can be locked from guardian with both 3F and 1F.
Also, PRMI with 1F can be locked by guardian but PRMI with 3F cannot be locked.
After several investigation, I found that sign of REFL135 was somehow flipped.
I'm not sure why this happens and it is necessary to investigate.

I checked MICH, PRC and PRMI can be locked by guardian, which could be on Nov. 3.
MICH with 3F, PRX with 3F, PRX with 1F, and PRMI with 1F can be locked but PRMI with 3F cannot (I forgot to check MICH with 1F but probbly can).

First, I thought it could be alignment, so I engaged ADS to IMMT1, IMMT2, and PRM while locking PRMI with 1F.
After the ADS, sideband bildup (POP90) became 0.2 from 0.05 (fig1).
Although POP 90 signals was about 1 on Nov. 3, I don't mind the absolute value because current LO power (10 dBm) was smaller than nominl (13.3 dBm).

After the alignment, Itried to lock PRMI with 3F signals but couldn't.
So, I checked MICH and PRCL one by one.
I found no strange behaviour on MICH 3F lock, however, I found PRX with 3F signals was somehow locked to anti-resonance of carrire light, which should be resonance for the carrire.
I'm not sure why this sign flip was occured (can LO change flip the sign of REFL135 signals ?).
Anywa, I fliped the sign of calibration factor for REFL135 and now PRX can be locked on resonance for the carrire by guardian.

We will continue PRMI recovery tomorrow.

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