[Gavin, Jenne]

We got commisioning time yesterday at 2W laser power to conduct a Q ringdown of the 12.988 kHz mode of ITMY. Before commencing we realised that the filter in alog 52836 needed altered to include ALWAYS ON & RAMP (3 seconds) options. In addition the bandpass filter in H1:SUS-PI_PROC_COMPUTE_MODE4_BP [FM2] required an alteration to extend to 13.01 kHz (210 Hz in oscillator bandpass land) after originally being set to have an upper limit of 13 kHz (200 Hz).

We also relised we needed to create the appropriate phase filters for the measurement. We then create the filters needed to ring up the 12.988 kHz mode on ITMY. Also we created a script which should make it easier to create phase filters in the future (attached). 

To do this we drove a high gain of approx. 1.85e8 through the Test Mass to an amplitude of approx. 100 and then zero the gain to measure the natural amplitude decay of the TM. 

Using the script described in alog 53013 we will extract the Q value of this mode (attached). The time constant tau = 63.6943 therefore Q = 2.5989e6 at 12.988 kHz (1/(f * pi * tau)).   This measurement will be an interesting addition to the ringdown data for the Acoustic Modal Loss Tomography analysis of the TMs.