betsy.weaver@LIGO.ORG - posted 09:34, Wednesday 10 November 2010 - last comment - 15:05, Wednesday 10 November 2010(322)
Q2 M0 alignment
Yesterday we finished resetting height and pitch of the Main Chain on Q2 after the mega mass swap. The TM is now sitting at at a hint over 22mm (21.7mm nom) from the LS bracket fiducial and the pitch error is 0.5mRad (2mm of beam displacement at the wall/4m lever arm from Q2 to wall) based on the optical lever. So, we are within spec on both of these numbers. We're moving on to the Reaction Chain and then will look at yaw and gap.
Images attached to this report
Comments related to this report
Moving to R0, we see that we are pitched out at the PenRe causing the lower bump stops to touch the Pen on M0. Looking closer at both chains, it seems the pitch error is at the UIM/Pen stage on both chains. The R0 UIM needed 100g moved from front to back on the mass in order to be better leveled. This was achieved by the following. R0 UIM - took off: 25g + 100g on top front turret 25g on back top left turret 50g 1st from cntr of 3 on right front top plate replaced it with: 37g + 37g on top front turret 75g on back top left turret 100g 1st from cntr on left back top plate After all of this, we adjusted out the pitch error seen in the Top Mass with the course pitch adjusters. We noticed that the R0 right adjuster looked off center compared to the left one, so we adjusted this one side which corrected pitch and looked more in line with the COM. Next we saw that R0 hung low by ~2mm and was also side shifted from M0 by ~1mm to the right (viewed from back). We added a 1.5mm shim set (total now = 3.5mm) to the left Top Stage Blade and a 0.5mm shim to the right (total now = 0.5mm). A final tweek to one of the R0 Top Stage Blade cartridges to adjust out a little yaw left the TM and the ReTM with a nice 5mm +/- 0.5mm gap. Tomorrow we will revisit M0 to adjust out some minor pitch error at the lower masses.