Changes

==Calculating Position of Each Bundle Support Mounting Rod==

==Tagger Microscope Placement in the Tagger Hall==

An Excel [https://zeus.phys.uconn.edu/halld/tagger/TAGM-4-2021/Bundle-Support-4-2021.xlsx spreadsheet] has been created to calculate the location of the bundle supports' mounting rods with respect to the focal plane coordinate system. This spreadsheet also calculates the length of the parallel railing end supports which need to be fabricated anew for each unique TAGM location on the focal plane. One last, but very important thing that the spreadsheet calculates is the shim size needed, during TAGM realignment, in order to achieve the proper tow angle between bundle supports during mounting. In addition to the spreadsheet, an AutoCAD [https://zeus.phys.uconn.edu/halld/tagger/TAGM-4-2021/Parallel_Railing_Parts.dwg drawing] used to design the three parallel rail components needed for each unique tagging energy spectrum starting position of the TAGM and a [https://zeus.phys.uconn.edu/halld/tagger/TAGM-4-2021/Beta-Angle12_5-to-11_06deg_modified.dwg drawing] for the current setup (β = 12.5^o to 11.06^o). These files are in US standard units (inches) and to scale with a tolerance of ± 0.001 inch.

When discussing the location of the TAGM within the Tagger Hall it is often easiest to reference the starting point of the energy spectrum being tagged. So for example, if the TAGM is said to be placed at 9.2 GeV this would indicate that the location of the most upstream column of fibers, with respect to the beamline, is such that a post-bremsstrahlung electron associated with a 9.2 GeV emitted photon will pass through the longitudinal axis of this column of SciFi's. This column is referenced as column #1 in figure 1 below. As the column numbers increase the electrons' energy increases, and as such the energy of the associated photon being tagged decreases. The β angle of each bundle support, which as you recall holds an array of 5x6 fibers with a 2mm² cross section, is selected to correspond to the average crossing angle for the electrons passing through these six columns. Therefore, for each bundle support there is a projection along this β angle that the support can be located. Since the crossing angle of the electrons only varies slightly over the bundle support width, there is a fair amount of play with the placement of the SciFi columns near the focal plane of the Tagger Magnet. To put this in prospective consider a bundle placed at 9.2 GeV. This 5x6 array of fibers will cover an energy range of 54 MeV and will see a change in β angle of only 0.11^o.