Jenne, Vicky. We took ~1 hour for sqz commissioning, from hours ~1-2 of lock.
Overall change is increasing the generated SQZ level from 12dB (60uW, last lock) to 14dB starting this lock (75uW). I don't think sqz is soley responsible for the lower range this evening (possibly some extra no-sqz noise). And, it feels like trends in the SQZ BLRMS are dominated by drifts of the technical noise and SRCL detuning over thermalization, so there isn't a clear correlation of more sqz = more range or better blrms. So while I do think more sqz is better, I think right now this test was probably limited by the elevated + drifting technical noise in the ifo, so I backed off the sqzing. Maybe with a thermalized IFO with stable technical noise, we'd see clearer trends of total noise vs. injected squeezing. Some notes from today:
- Tried to run with the 85uW (2x generated sqz) that we've used before, but too much confusion with this much squeezing at the start of lock, so stepped it back down.
- Playing the DARM DTT forward, from start of lock today, you can see how the extra injected squeezing makes DARM into a crazy v-shape while SRCL thermalizes for the first 30 minutes.
- It feels like injecting too much sqz is problematic with the SRCL thermalization in the first 30 minutes of lock, so I backed off from injecting more sqz, until we can figure that out more. For context, with 12dB before we didn't see SRCL too strongly (sheila, 70053), with 14dB now it might be kinda "ok" but still noticeable during early thermalization. To see 4.5dB FDS, we've typically injected >16dB sqz to saturate technical noise.
- Ended up with 75 uW OPO trans, so 14 dB generated sqz (NLG = 9.6). OPO temp has been tuned here.
- Measured the AS42 sensing function (aka SQZ-->IFO ASC). See ndscope here. With SQZ-ASC switch "on", we turned off the filter bank outputs, and stepped ZM5/6 used for asc. I didn't clear integrators so squeezer lost lock, but this allowed for some nice no-sqz time at the end:
- Brief No-SQZ time ~1.5-2 hours into lock: about 1370135726 - 1370135876 (started at 1370135747, but there was a big glitch at the start). This average is very short, but sees some excess non-sqz noise between 30-80 Hz today.
- Back to observing once sqz relocked