Yuhang and Yuefan

According to the experience of Eleonora and Matteo, the yaw of PR has a very narrow range. Also, we moved -2000 counts of PR and we observed a stronger vibration of green beam. So we guess maybe PR is touching the intermedium mass.

So we checked how much we moved and them tried to move it little by little and then have a look the spectrum to see if there is any difference of peak values. The measurement was down from -1000 to 2000 counts while the original position is 750 counts. The spectrum is attached in the sequence from -1000 to 2000.

We could see that after 1300, the high frequency noise spectrum is a bit higher than the reference. And we could see at -200 and -1000, the spectrums have parts lower than the reference.