Jennie W, Camilla
We set up this measurement by mis-aligning ITMX, ITMY, BS, PRM and SRM during the maintenance period (after the PSL and IM suspensions came back up).
NB. PSL was at 2W but ISS was off.
Then we adjusted IM3 till we were centred in pitch and yaw on IM4 TRANS.
Then we searched each direction of IM1 and 2 that gave us clipping on IM4 TRAns - IE. THE nsum DROPPEED.
Then we went back to a point near clipping on IM 2 and mpved IM1 in that DOF to try and bring back the NSUM since we managed to do this for all DOFs (up and down in pitch and yaw)we assume no translation oft he beam improves NSUM so we are probably not clipping through OFI.
First image is starting sliders.
Second is sliders after we aligned IM3.
This is ndscope trends throughout our tests. By far the largest improvement to IM4 Trans was moving IM3 and nothing we did with IM1 or 2 really improved this.
Attached is how much we had to move IM2 from it's nominal (20257,-4177) before the IM4 TRANS NSUM started drop, at which piont we're asumming we are clipping the faraday. It's closet (1000-200 counts) from clipping in one direction in Yaw, but centered in Pit.
Translating the beam through the faraday in Pit and Yaw didn't give us any better NSUM values. As Jennie explains we did this by moving IM2 (Tried IM2 Pitch to 19057 and 22057 (nominal 20257) and Yaw to -5577 and -3477 (nominal -4177) and using IM1 to correcting back towards the center of the IM4_TRANS QPD.
We conulde clipping the faraday is not an issue.
