(Arn, Kiss, Weavy, Trav)
Unfortunately, the ETMx TFs from last night returned all zero value data. SO, that needs fixing.
However, this morning we manually took all of the 6 DOF TFs on DTT and then hand compared all frequency peaks to the model. All peaks match the model frequencies to well within a few percent. SO, the ETMx is currently free and we should proceed with final ETMx HEPI and alignment work.
PDF below for all 6 main chain DOFs - cursors show a sample of peaks matching model frequencies.
Attached and for reference, are the trend of the calibrated osem signals for a week starting from wednesday oct 16th until thursday oct 24th
M0_DAMP and R0_DAMP are signals calibrated in urad and are representing relative motion between the structure (ISI) and the top mass suspensions. The largest shift over the week is 28 urad for M0 and 23 urad for R0
The other plots are individual osem signals, calibrated in um, representing the relative motion between the reaction and the main chain
The largest shift seen among those plots is at the lower left osem of the uim (L1_OSEMINF_LL) = 115um, which is clearly due to the reaction chain moving relatively to the ISI at the same time on Friday morning (see R0_DAMP).
M0 is the main chain R0 is the reaction chain L1 is the UIM L2 is the PUM, UL LL LR UR are upper left, lower left, lower right, and upper right osems
Further notes on Arnauds statement:
"...the lower left osem of the uim (L1_OSEMINF_LL) = 115um, which is clearly due to the reaction chain moving relatively to the ISI..."
could be clarified to
"...the lower left osem of the uim (L1_OSEMINF_LL) = 115um, which is a function of relative motion between the main and reaction chains, and the relative motion between the reaction chain and the ISI, and the possibility of a bumped flag in the process*. "
Specifically noteable is that none of the other 3 OSEMs on this same mass see this size of a motion which means that this signal is not representative of what the mass is actually doing in pitch/yaw. You cannot have only 1 OSEM signal change by a lot and assume that the mass pitches or yaws. 2-3 OSEMs must show motion that agrees.
*I am surmising that over the course of Thur/Fri HEPI adjustments (which are done 1 corner at a time), the ISI started out level, went unlevel corner by corner, and was restored to level by the time the 4th corner was finished. Possibly, during this unlevel time between corner 1 and 4 work, the ETMx suspension UIM LL magnet flag was close enough to get knocked around on the BOSEM a bit (likely because it started off not perfectly centered in range). When the level was restored, the flag snapped back into place, but a slightly different place relative to the LL BOSEM sensor - hence the observed larger 115um shift on just this OSEM.
Remember that this BOSEM senses relative motion between the main and reaction chain since the flag hangs on the main chain and the BOSEM hangs on the reaction chain. So, as Arnaud has discovered over the last few days of this investigation, quite difficult to use in diagnostics.