Changes

Up to 17 bundle supports can be mounted on the parallel railing system and instrumented in the TAGM. As the range of photon energies being tagged decreases (e.g. electron energy increases) the crossing angle (β angle) of the electrons with the focal plane also decreases. The smaller the β angle the more space along the X_FP axis a bundle support will occupy. Below an E_γ of 6.5 GeV (β = 9.5^o) the length of the parallel railing system can only mount a maximum of 16 bundle supports.

Up to 17 bundle supports can be mounted on the parallel railing system and instrumented in the TAGM. As the range of photon energies being tagged decreases (e.g. electron energy increases) the crossing angle (β angle) of the electrons with the focal plane also decreases. The smaller the β angle the more space along the X_FP axis a bundle support will occupy. Below an E_γ of 6.5 GeV (β = 9.5^o) the length of the parallel railing system can only mount a maximum of 16 bundle supports.

Since the β angle changes across the TAGM energy range, a universal bundle support β angle cannot be used. Starting with the most upstream bundle support (e.g. highest energy tagged photons) an initial bundle support angle is selected by taking the average of the crossing angles at the tagger magnet's focal plane for the electrons that pass through the center of the first and sixth fiber columns of that bundle. Recall that each bundle support holds an array of 5x6 fibers split into two 5x3 bundle halves. These halves are offset so that the bundle "pivot point" and the front center of each bundle half will all sit on the focal plane for β = 12^o. The pivot point is located at the midpoint of the bundle halves offset and the boundary point of the bundle halves along the bundle support long axis. The long axis that lies along the bundle support centerline passes through the pivot point, front mounting rod, and rear mounting rod. This fact is exploited during the calculations to follow. The pivot point is solely determined from the bundle support's design (e.g. offset distance) and is essential for fiber alignment on the focal plane. Regardless of the bundle β angle, if the focal plane passes through the bundle support's pivot point then the SciFi's will be at their optimal location with maximum fiber extension ± Y_FP being the same.             

Since the β angle changes across the TAGM energy range, a universal bundle support β angle cannot be used. Starting with the most upstream bundle support (e.g. highest energy tagged photons) an initial bundle support angle is selected by taking the average of the crossing angles at the tagger magnet's focal plane for the electrons that pass through the center of the first and sixth fiber columns of that bundle. Recall that each bundle support holds an array of 5x6 fibers split into two 5x3 bundle halves. These halves are offset so that the bundle "pivot point" and the front center of each bundle half will all sit on the focal plane for β = 12^o. The pivot point is located at the midpoint of the bundle halves' offset and the boundary point of the two bundle halves (e.g. along the bundle support long axis). The long axis, which lies along the bundle support centerline, passes through the pivot point, front mounting rod, and rear mounting rod. This fact is exploited during the calculations to follow. The pivot point is solely determined from the bundle support's design (e.g. offset distance) and is essential for fiber alignment on the focal plane. Regardless of the bundle β angle, if the focal plane passes through the bundle support's pivot point then the SciFi's will be at their optimal location with the magnitude of maximum fiber extension (± Y_FP) being the same.             

Once the β angle for the first (upstream) bundle support is set, derived from the the starting photon tag energy, each subsequent bundle support has a β angle offset from the previous one by a tow angle. Thus, as we look downstream from one bundle support to the next, the β angle differ by -(tow angle). Adjacent bundle supports will come in contact with one another at the SciFi end and form a triangular gap along their adjacent sides based on the tow angle.

Once the β angle for the first (upstream) bundle support is set, derived from the the starting photon tag energy, each subsequent bundle support has a β angle offset from the previous one by a tow angle. Thus, as we look downstream from one bundle support to the next, the β angles differ by -(tow angle). Adjacent bundle supports will come in contact with one another at the SciFi end and form a triangular gap along their adjacent sides based on the tow angle.

An Excel [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics spreadsheet(placeholder)] 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, AutoCAD drawings corresponding to a tagging energy spectrum starting at: [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 11 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 10 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 9 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 8 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 7 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 6.5 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 6 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 5.5 GeV], and [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 5 GeV] have been created. These CAD files contain the parallel railing system setup arranged for the corresponding photon energy range. These files are in US standard units (inches) and to scale with a tolerance of ± 0.001 inch.   

An Excel [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics spreadsheet(placeholder)] 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, AutoCAD drawings corresponding to a tagging energy spectrum starting at: [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 11 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 10 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 9 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 8 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 7 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 6.5 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 6 GeV], [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 5.5 GeV], and [https://zeus.phys.uconn.edu/wiki/index.php/Student_Projects_in_Nuclear_Physics 5 GeV] have been created. These CAD files contain the parallel railing system setup arranged for the corresponding photon energy range. These files are in US standard units (inches) and to scale with a tolerance of ± 0.001 inch.