> Note that since the beam separation of GreenX from PR2 to PR3 and PRM-PR2 line is about 2.2 mm far from the design, this 2.2 mm shift is consistent if the baffle is set with respect to the GreenX to PR3.
Unfortunately we are not well sure, but the mid-size baffle would be set with looking at the Hirata-san's document, so that would be just a coincidence.
By the way, now we are puzzled from the following measurements; the relative opening angle between the hypothtical incoming beam (PRM-PR2 line) and the GreenX beam (PR2-PR3 line). This should be about 0.02 rad in design.
> Even though it is difficult to say precisely, the beam separation is about 4.5 mm, which should be 6.744 mm according to the document of mid-size baffle
> After moving traverser, we measured the beam separation between GreenX to PR3 and PRM-PR2 line at PR3-side flange of PR2 chamber.
> So, the beam separation is about 10.5 mm at the flange.
But according to the measurements above, I can calculate as 0.013 rad in several ways (detailed below). This is too large difference! What is wrong??! Note: the distance of PR2-PR3 is about 11 m, so the (0.02-0.013)=0.007 rad difference would cause about 8cm shift error! at PR3.
- Point A, where "4.5 mm" beam separation was measured, is about 336 mm away from the PR2 HR surface. If you simply calculate, 4.5mm/336mm = 0.0134 rad.
- Point B, where "10.5 mm" beam separation was measured, is about 800 mm away from the PR2 HR surface. if you simply calculate, 10.5mm/800mm = 0.0131 rad. So this number is consistent with the one calculated above.
- If you still suspect a certain amount of "shift offset", you can estimate the angle in the different way to cancel such offset. Consider the differention of Point A and Point B. (10.5-4.5)/(800-336)=0.013 rad.
So strange.
Maybe one can say that "because it seems these beams separate designed distance at the PR3 chamber, this would be the evidence that these beams seprated 0.02 rad", but I think it might be better to check if this would be true or not at the site. In umy understanding, according to the design, the beam separation in the PR3 chamber must be about 215-227 mm in the Y direction; this is the designed 0.02 rad case. If in the 0.013 rad case, this would be about 143 mm. Note that this is comparable to the recoil mass radius...