On Friday, I copied in the R0 tracking of the main chain for all the quad models (alog 54416) from LLO. I also copied over the medm screen updates that LLO had started that go with these.  Since we're using it at both sites, and it already seems good, after chatting with Stuart at LLO, I created an ECR (E2000011) which Peter Fritchel has approved.

Today Dave restarted all the quad sus models, so we've got the new paths implemented now.  Before letting the suspensions out of SAFE, I set the gain on the new R0 paths to zero.

I also copied over the suspension Foton files that LLO uses (Anamaria and Stuart had recently checked them in to the userapps/sus/l1/filterfiles/ folder, so I just had to svn-up them).  During maintenance, I turned on both the ETM R0 length tracking paths, with the same configuration that LLO is using (alog 50901). 

I did a quick injection test by pushing on ETMX M0 at 0.15 Hz, and then turning on and off the R0 tracking.  As expected, when the R0 tracking is on the displacement between the chains (as measured by both the L2 and L1 witness channels) is varying much less.  I mostly used the same gain that LLO does (-20), and was able to turn it up by a factor of 2 without trouble.  But turning it up a further factor of 2 caused oscillations.  So, we probably have headroom of a factor of 2 in gain, but not a factor of 4. 

Robert and I are on the board for tomorrow afternoon to do more thorough injection tests, so hopefully we can say more quantitatively after that what kind of improvement we're seeing in the realm of scattered light.