Following up from yesterday's test (63755) where HAM7 Y blends were matched with HAM5, I am now comparing the longitudinal suspoint motion between FC1 and SR3 projected respectively from HAM7 and HAM5 ISI motion. On the last page of the pdf attached, we can see a clear broadband improvement from 0.4Hz-20Hz by up to a factor of 5 at 1Hz. This is due to the overal RY improvement from the fine CPS installed on HAM7. The individual projections are shown on the first two pages of the same document.
Data was taken for 1hour from HAM5 and HAM7 at 09:30 UTC on June 29, projecting each dof onto the suspoint of FC1/SR3, using the CART2EUL saved in the ISI2SUS_projection_file.mat under the userapps/release/isc/common/projections directory. The script to generate those plots lives in the llo control room under /home/arnaud.pele/Documents/seismic/ham7_suspoint/fc1_projection.m
Data was saved under a .mat file and can be downloaded from https://llocds.ligo-la.caltech.edu/data/arnaud.pele/LHO_FC1_suspoint_projection.mat
Spectacular! Well done fine CPSs and the SEI team! For everyone else's benefit, this is the "final answer" demonstration of the success in upgrading the HAM7-ISI vertical Capacitive Position Sensors (CPS) from the "coarse" readout to the "fine" readout system (already in use on Stage 2 of the BSC-ISIs). There was never an IIET Ticket associated with the upgrade since it was in the blurry lines between - "It's the A+ baseline plan" and - "we've just now decided that any chance we get we're going to replace coarse with fine when it's convenient" but it was approved via ECR E2100346, and is accompanied by - The RODA M1900160 - The DCN E2100347
Jeff asked how those HAM HLTS suspoint compare with a BSC suspoint. I used ITMY as an example, with data taken at the same time as for HAM5-7. While HAM7 is not quite at the ITMY level, it's close at around 1-2Hz.
Somehow in the first page of the pdf from the main log, the HAM5 Rz to SR3 contribution is wrong. Given Rz is comparable between the chambers, the suspoint contribution should be lower for HAM5 than HAM7 because of the shorter lever arm between SR3 and the center of the table.
While it doesn't change the conclusion, this plot needs to be updated.
On the call on Friday there was some discussion about the ITMY vs. FC1 comparison. Just for interest, I've attached a plot of the original motion requirement for the BSC and HAM ISI. In the plot we see a few things of note. First, the performance goal at the microseism is about the same. There's a small difference in how we dealt with the goals below 0.2 Hz. The big difference in the req's is what happens above 0.6 Hz (set to catch the first mode of the triple). Here we see that the BSC should be much better. In comparison to these old expectations, it's amazing how well the HAMs are doing at 1 Hz.
