“Science is the belief in the ignorance of the experts” -- Feynman

The analysis of laser measurements for Exp 03045 (my thesis) are basically done now.  I have the position of the target, and most importantly, the vectors from the center of the target to all of the 32x32x17 pixels of HiRA.  Just for fun, I also found the vectors from the target to all ~200 phoswiches in the 4Pi.  Ok, it wasn't really for fun, we do need those numbers.  But it was fun walking over to the BPS with Skip and a tape measurer to confirm that a distance found in a 10 year old thesis really was the distance I was needing for calculations.

Now for some pictures:

This is a view of the 4Pi modules, forward array, and hira from above.  You can see that  the modules are closest to the target (in the center of the ball), then hira is a bit farther away, and the forward array is even further away.  In this view, the beam comes in from the bottom and moves upward.

One question you might have (we certaintly did): How close is the center of the target to the center of the 4Pi?  The answer? 8 mm

The pic below is also from above the ball, the z-axis is the beamline and the big white dot is the center of the ball.  If you look near the big white dot, you should see the plane of the target. 

Sine the target is slightly off from where we expected, how about HiRA? We know how we designed the array to be arranged, but did we succeed in putting it together in the way it was designed?  

The answer:  yes.  Well, the normal vectors from the face of each telescope are within 1°of where we expected them to be. Below is a plot of differences of differences.  Basically, 0 means the telescope is pointing the way it should be, .8 means it's .8° off.