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AdV-ISC (Commissioning up to first full interferometer lock)

mantovani - 9:58 Thursday 12 September 2019 (46902)

BNS range fluctuation

Yesterday after the AA working point tuning the Range was increasing, but looking better the data the increase was already started hours ago (slow drift).

I was trying to correlate the Range with the Ogain of the Cavities but there was not a nice correlation as usual, something else was affecting it (may be the Og of the cavities was spoiled by the alignment), see Figure 1.

I was able to correlate nicely with the Inputs temperature, which means that the Etalon at the moment is the stronger contributor to the Range fluctuations (which increase the urgency to control the etalon).

In Figure 2, the data used for the analysis are shown (the Range drops have been eliminated).

In Figure 3 the correlation of the Range with the temperature of the inputs mirror are shown.

In Figure 4 the correlation of the Og Cavities with the temperature is shown.

Images attached to this report

Comments to this report:

mantovani - 11:54 Thursday 12 September 2019 (46904)

Looking at 70 days of data the optimal working point can be more or less identified looking at the Optical gain variation for the cavities and for the Range.

The data set is visible in Figure 1.

The Optical gains shows some steps that are been compensated, see Figure 2. The red curve is the one used for the analysis

in Figure 3 the BNS range is plotted as a function of the Input mirror temperature and the maximum is obtained for 19.58 deg for the NI and 19.61 for WI.

In Figure 4 the OG for the cavities is plotted as a function of the Input mirror temperature and the maximum is obtained for more or less the same temperatures found for the Range.

To be re-measured with a controlled experiment.

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mantovani - 14:26 Friday 13 September 2019 (46914)

Looking also to the BBH range the optimal position is the same for the BNS range (I was supposing that they would be more affected by the Etalon since it affects the sensitivity mostly at low frequency but indeed they behave the same as a function of the etalon).

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