Virgo Logbook

Reports 1-1 of 1

Detector Characterisation (Spectral lines)

Paoletti - 11:11 Tuesday 25 July 2023 (60968)

Triplet of HF lines in hrec

There are three lines in hrec, clearly mains-related, that show an S/N ratio of about 10 at 5900, 6000 and 6100 Hz.

They are consistent with most magnetic sensors in CEB, not in WEB or NEB. The same is true for microphones.

We suspect that they are present in the UPS voltage lines, but these are sampled at 2kHz so there is no hope of them being visible.

They could be generated by the CEB UPS (50 Hz sine wave reconstruction).

Images attached to this report

Comments to this report:

Paoletti - 13:26 Tuesday 08 August 2023 (61168)

Indeed, these lines are present in both UPS and IPS lines, with a level up to two orders of magnitude higher than all mains harmonics.

The coherence with Hrec is very high. This leads even more toward the UPS technique of generating the 50 Hz mains line as the likely source.

Thanks to Emmanuel Pacaud who reminded me that these channels are temporarily stored at a sampling rate of 20 kHz.

Images attached to this comment