Run 2-4 z location offset.  
When the hall probe was aligned in z for runs 2-4, it was not placed properly.  Run 3 has the location of the maximum field as being z = -7.3 +/- 0.3 mm .  This seemed like a large distance so the Bz vs z measurement was repeated in run 17 using a different axial hall probe.  This data shows (Bz vs z fine steps near mechanical z = 0.png) the maximum Bz field to be at -1.39 +/- 0.18 mm.  The run 17 was alignment was aligned by the alignment group using optical tooling  and then it was double checked using a micrometer and found to be correct.   When one uses the run 2-4 data, one should add 5.91 mm to the z value in the files to obtain the correct z location.

Scott Anderson  6/15/2017