Reports 1-1 of 1 Clear search Modify search
Environmental Monitoring (Environmental Monitoring)
Fiori, Tringali, Paoletti, Bersanetti, Gherardini - 7:23 Thursday 11 December 2025 (68350) Print this report
Magnetic line injection

This evening, we resumed the magnetic line injection (elog #62843). Due to some issues with the Automatic Injection code, we used the ENVnoise process from the VPM interface instead.

We tuned the amplitude of the lines, starting with the WE building.

All the lines are injected simultaneously. The frequencies and amplitudes (sent to DAC) are reported in the table below. 

Frequency (Hz) Amplitude (V)
2.5  0.4
3.6  0.32
4.6 0.32
5.7  0.36
6.7  0.36
7.4 0.36
8.9  0.4
10.5 0.22
11.9 0.28
13.5 0.34
15.3  0.38
17.5 0.4
19.1 0.48
22.5 0.54
24.5  0.58 

 

During the tuning, the interferometer unlocked and the auto-relock process got stuck. We contacted Diego, who fixed the problem.

*** We left the WEB magnetic line injection running for the entire night, and tomorrow morning the injection will be stopped manually. ***

Comments to this report:
Tringali, Fiori - 7:27 Thursday 11 December 2025 (68352) Print this report

The magnetic line injections were stopped at 06:18:44 UTC.

fiori - 14:40 Thursday 11 December 2025 (68357) Print this report

A first look at data show that:

injected lines at 6.7 Hz and above are all well visible in hrec (using 1000s spectral resolution)

Yet, the choice of setting lines's frequency at multiples of 0.1 was not good, because of the presence (forgotten) of an underline 0.1Hz spaced comb which is largely coherent between hrec and magnetometers. Therefore, we would possibly repeat the injection with a better choice of frequencies. 

Injected lines below 6.7 Hz are not seen in hrec (although there is margin of improving, for example removing loud glitches...). These freqeuncies should be amplified. Indeed there is margin (before saturating the amplifier) to safely double their amplitude. 

Images attached to this comment
Tringali, Fiori, Berni - 22:55 Thursday 11 December 2025 (68362) Print this report

Due to the comb lines spaced by 0.1 Hz, we changed the frequencies of all injected lines and increased the amplitude of the first four lines in order to improve their SNR.

*** The injection started at 21:02:51 UTC in the WE building, and it will be stopped manually tomorrow morning****

Frequency (Hz) Amplitude (V)
2.577  0.8
3.677  0.64
4.677 0.64
5.777  0.64
6.777  0.36
7.477 0.36
8.977  0.4
10.577 0.22
11.977 0.28
13.577 0.34
15.377  0.38
17.577 0.4
19.177 0.48
22.577 0.54
24.577  0.58 

 

Tringali - 10:09 Friday 12 December 2025 (68365) Print this report

The WEB magnetic line injections were stopped this morning at 08:29:12 UTC.

fiori, tringali, paoletti - 17:02 Friday 12 December 2025 (68372) Print this report

We had a look at tonight injections and compared them with those of the previous night

The examined periods are:

17000 s starting from Dec 11, 01:00 

17000 s starting from Dec 11, 22:20 

We used a spectra resolution of 2000s.

The first dataset is polluted by a 0.1 Hz spaced  comb, which is present in the Voltage and current monitors of the large coil amplifier as well as in the witness magnetometer (placed close to the WE tower).  We suspect this might be related to the injected lines being multiples of 0.1 Hz.  The problem with this is that Hrec itself is polluted by a 0.1 Hz comb, although it is not related with our injected noise. Infact, as shown in Figure 16 (example around the injected line 10.5Hz) the same 0.1 Hz comb was present also when not injecting (purple). 

Therefore, in the second set of injections we moved the lins frequencies at **.*77 Hz. This time we noticed a somehow larger spectral noise "floor" in the Voltage, Current monitors and magnetometers as well, which resembles a comb spaced by 0.77 Hz. However, this turns out to be better, because no such comb is present in Hrec a priori.

Going through the injected lines one by one (Figures 1 to 15), it looks that we have achieved a good measurement of CF at most of them. Missing ones for now are 3.6, 4.6, 5.7 Hz, which might be recovered improving the analysis.

We do not have a good explanation for the extra noise  produced by the amplifier, it seems related to a non linearity in the amplifier itself, since the spectrum of the injected noise (ENV_NOISE_MAG_WEB) does not show this features.

 

Images attached to this comment
Search Help
×

Warning

Error

The present report has been modified outside this window. Please check for its integrity in the main page.

Refreshing this page will move this report into drafts.

×