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AdV-COM (AdV commissioning (1st part) )

Allocca, Chiummo, Degallaix - 2:03 Wednesday 05 July 2017 (38427)

SSFS noise injections for CMRF measurments and OptChar tasks

Tonight we performed several noise injections on SSFS in order to estimate the CMRF. The details of the measurements and all the GPS will be put tomorrow.

After that, we collected some stretch of free swinging arm cavity data for the ringing analysis for the finesse measurement. The data will be analyzed later.

Finally, we started doing some meaurement of arm lock/unlock for the cavity RTL estimation, but at some point Metatron froze, and Diego helped us in restoring the working condition.

We re-locked the ITF in LOW_NOISE_2 and we started magnetic noise injections at GPS = 1183248200 on West End, following Irene's instructions.

Comments to this report:

Allocca, Chiummo, Degallaix - 12:08 Wednesday 05 July 2017 (38435)

Here some times from last night. All times are local times

SSFS noise injection

22:10 (5 min), noise injection to SSFS. Coherence mainly about 1 kHz.
Change the spectral shape of the injected noise to inject larger noise toward low frequency

22:30 (5 min), better, noise injection visible from 100 Hz. Try to increase the amplitude of the noise
Unlock, design a new filter with still larger amplitude in the low frequency band

22:37:30 (5 min) noise injection, slighlty better

23:46:50 Fmod enable

New filter shape for the noise injection: band pass centered around 30-40 Hz, not highly selective so we will still have noise injected outside the transmission band

00:04 (5 min) noise injected, quite good, well visible in h from 20 Hz up to high frequency

00:12:40 (5 min), increase the amplitude, best injection of the night, this data should be used

00:20:30 (2 min), increase again the amplitude of the noise, coherence not better in high frequency

Arm cavities free swinging and lock / unlock

00:54:20 North arm free swinging, scanning speed may be too low

01:05:00 Series of lock / unclock and at the same time series of free swinging

Problem with the logic of boolean and Metatron not cooperative. Remote help from Diego.

02:00 Go back to low noise, launch of the script for magnetic noise injection

mwas - 16:59 Friday 07 July 2017 (38489)

Used the loudest broadband SSFS noise injection to look at the projection of frequency noise at low frequency.

Figure 1, shows the noise budget at the time of the noise injection using the Optickle model coupling (times a factor 5). This shows that the zero at ~100Hz in the frequency noise coupling that comes from the Optickle model is actually what happens in reality (although with different levels). In particular above the zero the noise coupling in higher than below the zero compared to the Optickle model.

As a simple solution added on top of the Optickle model frequency noise coupling a flat in frequency coupling. The projection for that case is shown on figure 2, it works well below and above the pole, but not at the pole frequency, presumably because the phase of the flat noise coupling added by hand is wrong.

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