Sheila, Jennie W

[Log from Wednesday afternoon]

Sheila stopped the bias voltage on L3 ETMX stage as was done earlier today, at each stage we checked the DARM spectrum and the PCAL to DARM TF to make sure we are not getting confused by a noise change vs. a calibration change.

The PCAL to DARM measurements are saved in /ligo/home/jennifer.wright/Documents/Bias_ESD/2024-03-27-PCAL_DARM_BB.xml. The calibration doesn't change much between bias voltages of 140V and 190V but changes by about 2% in magnitude around 40-50Hz.

The DARM measurements are saved in /ligo/home/jennifer.wright/Documents/Bias_ESD/EX_bias_change_March2024_repeat.xml.

The top left graph compares the different measurements of calibrated CAL-DELTAL_EXTERNAL using 190 V bias, the bottom the different measurements using 415V and the right hand graph compares all of them. Maybe I can see a difference between 190V and 415V but it seems pretty noisy across measurements at the same voltage so hard to draw a conclusion.