Daniel, Sheila, Keita

This morning Peter King realinged the PMC again. The attached plot shows the PMC HV mon recorded yesterday afternoon, and now after the alingment, the peaks have gone down by about a factor of 3, and the noise in the ISS first loop out of loop PD also decreased.  We can further reduce the peaks in the HV mon by increasing the loop gain to 27dB.  We saw the loop start to oscillate with a gain of 30dB, which might explain the braodband noise in DARM we saw when we went to 30dB the other night. (30682)

In the attached plot, LSC-EXTRA_AI_1, which is calibrated into volts at the ADC.  There is a SR560 with a 10 Hz high pass and a gain of 100 between the monitor point and the AI input, so combined with the 1/50 gain of the monitor, 1 V here is 2 Volts applied to the PZT.  The PZT is a custom made PZT, PI PAHH-0013, the capacitance is 63nF, travels 4um/kV.  We have a 3.3k resistor, so the pole is about 770 Hz.  So to calibrate this channel into meters:  V LSC_EXTRA *2(Volts to PZT/Volts LSC_Extra)*4um/kV= 8e3pm/Volt, with a pole at 770 Hz. 

The measurement from yesterday was made in full lock, with the ISS second loop at full bandwidth (PDB is out of loop).  This morning's measurements were made without the ISS second loop on.