Reports until 17:09, Saturday 24 December 2022
H1 SQZ
nutsinee.kijbunchoo@LIGO.ORG - posted 17:09, Saturday 24 December 2022 - last comment - 13:15, Monday 26 December 2022(66533)
Seed hunting on CLF refl path

Camillia Daniel Nutsinee

As part of our seed hunting exercise on Thursday we temporally added a 1611 diode in the CLF refl path to see what beat notes are out there. This is the path for CLF refl RF 6 and if we have seeding issue we should at least see a 3MHz here. The only line we saw in this path was the 1.3 dBm RFL signal at 104.65kHz that is the result of 3 MHz beating with 3.104 MHz. It's unclear where 103.4 kHz came from but it's only -77dBm. The noise level was -102 dBm. No 3 MHz line was present. We maxed out our CLF input power for this measurement. The launch diode read 0.86 mW.

 

With this measurement we concluded that if there is any seeding, it has to be at least at < -100 dBm level.

 

Attached also a DC readout of the 1611 during the measurement (120uW into the diode) and a RF amplifier we used. We were only 1/3 efficient with our mode matching into the diode (it's got a tiny window). 

 

We have removed our setup and the CLF path is cleared.

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Comments related to this report
nutsinee.kijbunchoo@LIGO.ORG - 13:15, Monday 26 December 2022 (66555)

Corrections from Daniel:

that is the result of 3 MHz beating with 3.104 MHz
-->
that is the result of 3.125 MHz (CLF) beating with 3.020 MHz (RLF)

it has to be at least at < -100 dBm level.
-->
it has to be at least at < -100 dBc level.