New IM4 nominal bias sliders: [13350, -5056].
Good range for IM4 bias after the initial alignment procedure is [13350 +- 2400, -5056 +- 330] assuming that the MC is behaving well.
The "good range" gives you +-2 mm displacement on the PR2 baffle, which is a non issue for clipping, or +-60urad in IM4 rotation.
IM4 slider calibration was remeasured, it's: 0.025 rad/bogorad for PIT, 0.182 rad/bogorad for YAW.
The slider change from yesterday, i.e. [3364.4, -118] slider counts (micro bogorad), corresponds to [88.3, -21.5] urad physical rotation.
What was done:
After the LVEA temperature settled, IM4 was scanned while the PR2 baffle and the SRM baffle was monitored. Before I started IM4 [P,Y] was [9985.6, -4938].
For IM4 YAW, I was able to see when the beam barely touched the PR2 baffle edge, and when the straight shot beam on SRM baffle disapperaed. I made the average to determine when the beam is 50% blocked.
For PIT the driver railed before I was able to completely block anything, I only recorded when the beam barely touches the PR2 baffle edge.
| barely touches | Completely blocked | Average | |
| Left, Y bias | 800+-100 | 1800+-100 | 1300+-70 |
| Right, Y bias | -6300+-200 | -12200+-200 | -9250+-140 |
| Top, P bias | -25300+-1000 | NA | NA |
| Bottom, P bias | 52000+-1000 | NA | NA |
Since baffle hole appears to be a 65.4mm diameter circle, and since the beam is supposed to be 26mm from the right edge, the new position is
P = (52000-25300+-1400)/2 = 13350+-700.
Y =26/65.4*(1300+-70) + 39.4/65.4 * (-9250+-140) = -5056+-90.
Slider calibration is the angle over the baffle diameter 65.4mm/17m divided by two divided by the slider difference, i.e.
calibration for P = 65.4e-3m/17m/2/(52000E-6+25300E-6+-1400E-6 bogorad) = 0.0249(1+-0.02) rad/bogorad
for Y = 65.4e-3/17/2/(1300E-6+9250E-6+-160E-6) = 0.182(1+-0.015) rad/bogorad