Keiko, Masayuki, Kiwamu,

While Miyo kun is writing a report on the installation of a pair of the QPDs, we here report on a first look at the signals from them.

Here is a set of the spectrum taken with the newly installed QPDs behind MCe.

The below are several observations.

• The QPDs, both in pitch and yaw, are sensitive upto 10 Hz. It seems that frequencies above are some kind of sensing noise.
• We found a unidentified peak in the spectrum of QPDA2 PIT at 4 Hz.
  • Looking at coherence, we found that the MCO_OPLEV had the highest coherence of 0.7 at 4 Hz.
  • The other two oplevs also had a coherence of about 0.5.
• For comparison, one can look at some past data taken by the tilt sensors for MCe (2512) in which a broad-ish peak at 5 Hz can be seen.