Sheila Dwyer, Heather Fong

During today's commissioning period, we wanted to investigate how the fire pump from March 1 affected DARM (alog entry 34525). To do so, we injected signals into the HEPI loops: HAM1-HAM6, BS, ITMX, and ITMY, for x-, y-, and z-directions. The injected signal had a frequency bandwidth of approximately 10-40 Hz, which is similar to the bandwidth that was affected by the fire pump.

The data for the injected channels are available here. We did not observe coupling between the HEPI motion and the DARM spectrum. For an example, please see the attached figure "HEPI_excitation_ITMY_Z.png".

We also compared our z-direction results to the PEM injections from the beginning of O2, and we observed coupling in HAM1 that is consistent from what was observed before. The plot with which we compared can be found here, and our plot is attached to this log entry ("HEPI_excitation_HAM1_Z.png").