My investigation into the alignment shifts of the H1 IMs (IM1, IM2, IM3) led me to investigate the IMs at LLO in L1.

I have identified three events where the L1 IMs changed alignment for the same alignment drive.

Chart-1 shows L1 IO IM1-3 optics on Sept. 13th, Nov. 14th, and Nov. 25th, when earthquakes tripped the L1 HAM2 ISI.

• On Sept. 13th, L1 IM1 pitch shifted -20.4urad, and L1 IM3 pitch shifted 37.1urad
• On Nov. 14th, L1 IM2 pitch shifted by 6.4urad, and L1 IM3 pitch shifted -22.6urad
• On Nov. 25th, L1 IM3 pitch shifted by 7.1urad
• All other shifts were 5urad or smaller (an arbitrary setpoint for tracking/correcting alignment changes in the IMs at LHO)

The chart also shows the amount of shaking of the L1 IM optics and the L1 HAM2 ISI.

• On Sept. 13th the L1 HAM2 ISI shook by 1mm in X direction, 0.8mm in Y direction, and 1.6mm in Z direction
• On Sept. 13th the L1 IM optics shook between 1.8urad and 6.5urad
• On Nov. 14th the L1 HAM2 ISI shook by 0.01mm in the X, Y, and Z directions
• On Nov. 14th the L1 IM optics shook between 0.6urad and 1.9urad
• On Nov. 25th the L1 HAM2 ISI shook by 0.06mm in the Y and Z directions, and 0.04mm in the X direction
• On Nov. 25th the L1 IM optics shook between 1.3urad and 3.3urad

This data shows that the alignment of the IMs in L1 are vulnerable to alignment shifts after a HAM2 ISI trip. 

Corresponding alogs regarding LHO H1 IO IM1-3 alignment shifts are H1alog22913, H1alog22956, H1alog23415, and H1algo25075.

Attached:

• Chart-1 shows Sept. 13th, Nov. 14th, and Nov. 25th, when earthquakes tripped L1 HAM2 ISI
• Chart-2 showing the alignment settings for the LLO L1 IMs (IM1, IM2, IM3) for each even
• PDF file with plots from each event