Reports until 14:26, Thursday 13 May 2021
H1 ISC
varun.srivastava@LIGO.ORG - posted 14:26, Thursday 13 May 2021 (58946)
Reducing Modulation Depth Test

Georgia, Jenne, Varun

We went to NLN_CAL_MEAS state and walked the 9 MHz and the 45 MHz modulation depth using the scripts 'step_45MHz.py' and 'step_9MHz.py' in /opt/rtcds/userapps/release/isc/h1/scripts

One issue with the measurement was that with the dither lines off the alignment was drifting at low frequencies: 10Hz to 20Hz. The key summary of the results is that the nominal O3 values are good and changing the modulation depth has little affect on the noise in DARM. I have attached 2 plots showing the low frequency changes in DARM. First for stepping the modulation depth of the 9MHz. Second one is for changing the 45 MHz modulation depth. The measurement template is saved at /ligo/home/varun.srivastava/LHO_work/O4_comm/2021_05_12_RF_reduction.

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