Note that there are two ways to rotate the theodolite through 180◦ : So in principle, we could mount the theodolite over the mark on the floor, line up to the one on the wall and rotate 180◦ and we would be looking also as before. There is also a mark on the floor after the beam dump. Instead there is a mark at the point where the beam intersects the wall after Miniball. With HIE-ISOLDE it is no longer possible to open up a port-hole in the magnet and there is, in any case, no line of site to the wall and no mark on the wall. So if the target was centred on the crosshairs of the theodolite, it was correct. This meant the theodolite was looking along the direction exactly opposite the beam direction. In the past, we used markings on the floor and on the wall behind the bending magnet before Miniball (viewed by opening a port-hole in the magnet) to set up the theodolite, so that it was directly over the point on the floor and looking at the point on the wall. 3.2 Conversion from Miniball to CERN coordinate system. Alignment with the help of the alignment service Nigel Warr 18th September 2015ģ The CERN Coordinate System 3.1 Conversion from CERN to Miniball coordinate system.
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