Spent all day trying to go back to the blue trace in the attached (which is from yesterday afternoon), but we came back to red, which is basically the same as this morning except the frequencies of three finger structure.
We re-routed the cables twice, and neither of these attempts recoverd the Q of 1.75 and 1.4Hz thing. So much for my "bundling=bad Q for translational" theory which sounded good.
Unrubbing excersize reliably eliminated the elevated noise floor 0.8Hz-6Hz that probably came from rubbing, and made the Q of some modes good, but did not do it reliably for 1.75Hz and 1.4Hz.
At this point I have to say it's unlikely that we can reliably make it like the blue trace even if we go in the chamber tomorrow, so if nothing special comes up we need to button down. I asked Arnaud to run his TF. Tomorrow Jim should run his stuff again.
As for the three finger structure (0.6-0.8Hz), we need to live with it, it's not unique to this pilot unit (see the X and Y free swing spectra, due to low resolution it looks like two fingers for Y, but the point is that there are three resonances between 0.6 and 0.8Hz for X).
BTW we eliminated another potential rubbing problem, which is the cable loop around the table cloth. We found that the clearance was less than a mm, probably something like 0.5-0.7mm. This depends on cable routing again, due to some strange way the cable goes in to the top mass, comes out, loops around the table cloth, goes in the top mass again, and finaly going to the ISI table.
Anyway, it was not touching but the head room was small, we pulled the cable on the cable clamp inside the top mass and made the clearance more like 2 or 3mm.
Have a few photos of the finicky beast (aka TMS). Photos are of cabling work (for run from Upper Mass to ISI Optics Table & for the loop around the Upper Mass), and final locations of the "fine balance masses" (which are a pair of 1/4-20 screws on the front end of TMS Optics Table).
Yesterday, we made two attempts at getting to the "blue" state from Tues:
- Three runs of cable up to the ISI (with cable tie down at Upper Mass to keep cables from touching hole they spring from)
- Four runs of cables up to the ISI with cable tie removed (this is the final configuration we left the TMS in).
