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AdV-DET (Commissioning)
mours - 7:53 Friday 26 May 2017 (37739) Print this report
RFC at 8Mhz and B1p at 112 Mhz

The RFC 8 MHz signals has been added this morning as well as the B1p_PD2_112MHz_mag signal.

Comments to this report:
genin - 8:41 Friday 26 May 2017 (37740) Print this report

The RFC didn't relock after this operation. I had to change de demodulation phase from -2.229 to 1.529 rad.

ACL_CONST_CH    RFC_6MHz_phi0     "rad" 0      LOOP_FREQ 1.529 #-2.229

I have not fine tuned the demodulation phase but it was enough to relock the RFC and lock the 3km arms.

mantovani - 10:17 Friday 26 May 2017 (37742) Print this report

It has been finely tuned at 1.9066 rad

bersanetti, ruggi - 18:03 Friday 26 May 2017 (37750) Print this report

We acquired the new RFC_8MHz_I channel into LSC_Acl and used it to restore the CARM_SLOW loop; its phase has been adjusted and the value saved in the SIB2_Photodiodes process. Then we closed the loop and it worked with the same parameters as with the 6MHz error signal, as their SNR are similar, but we needed to add a little offset to the loop (-0.035) after looking at the signal when the RFC was still locked on the INJ side.

However we noted that such loop, which has not been optimized for noise/science mode yet, quite spoiled the correction on the ITM in the region where the dither lines are (see the Figure, purple is with loop engaged). Therefore we disabled it for the time being but we can now work on its improvement and test it during lock acquisitions.

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