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Moving the Tagger Microscope (view source)
Revision as of 22:09, 31 March 2021
, 22:09, 31 March 2021→Calculating Position of Each Bundle Support Mounting Rod
[[Image:Bundle_support_displacement.jpg|right|thumb|425px|Figure 16: Sketch showing the X-displacement along the focal plane (Δx) from the center of the first fiber column to the center of the sixth fiber column of the first bundle support.]]
[[Image:Bundle_support_displacement.jpg|right|thumb|425px|Figure 16: Sketch showing the X-displacement along the focal plane (Δx) from the center of the first fiber column to the center of the sixth fiber column of the first bundle support.]]
<li>Select a starting energy for the photon tagging array (highest γ energy to tag)</li>
<li>Select a starting energy for the photon tagging array (highest γ energy to tag)</li>
<li>Using [https://halldweb.jlab.org/wiki/images/b/b6/Counterbounds2017%28b%29.xlsx hodoscope energy bin bounds] interpolate the crossing angle with respect to the focal plane (β<sub>1</sub>) of an electron associated the highest energy to be tagged (starting E<sub>γ</sub>)</li>
<li>Using [https://halldweb.jlab.org/wiki/images/b/b6/Counterbounds2017%28b%29.xlsx hodoscope energy bin bounds] interpolate the crossing angle with respect to the focal plane (β<sub>1</sub>) of an electron associated the highest energy to be tagged (starting E<sub>γ</sub>)</li>
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[[Image:popsicle_stick_fiber_angle_top_view.png|center|thumb|800px|Figure 18: Sketch showing the "pivot point" that should always sit on the focal plane to provide the optimal fiber alignment. The green line running through the pivot point represent the placement of the focal plane for a bundle support with β = 12<sup>o</sup>, while the red line shows the placement for β > 12<sup>o</sup>.]]
[[Image:popsicle_stick_fiber_angle_top_view.png|center|thumb|800px|Figure 18: Sketch showing the "pivot point" that should always sit on the focal plane to provide the optimal fiber alignment. The green line running through the pivot point represent the placement of the focal plane for a bundle support with β = 12<sup>o</sup>, while the red line shows the placement for β > 12<sup>o</sup>.]]
As shown in Figure 18 by the red and green lines, if β ≠ 12<sup>o</sup> then the front face of the first column of SciFi no longer sits on the focal plane. This offset must be accounted for. The Excel spreadsheet starts by finding the optimal first bundle support crossing angle (β<sub>avg</sub>) and places the front center of the first column of SciFi on the X<sub>FP</sub> location corresponding to E<sub>γ<sub>o</sub></sub>. Depending on β's departure from 12<sup>o</sup> the pivot point will be displaced from the focal plane. The spreadsheet calculates the (Δx, Δy) needed to return the pivot point to the focal plane and keep the first fiber column's longitudinal axis on the E<sub>γ<sub>o</sub></sub> electron's path. The spreadsheet's title for this is "Pivot Point Move" and the description is detailed below.
As shown in Figure 18 by the red and green lines, if β ≠ 12<sup>o</sup> then the front face of the first column of SciFi no longer sits on the focal plane. This offset must be accounted for. The Excel spreadsheet starts by finding the optimal first bundle support crossing angle (β<sub>avg</sub>) and places the front center of the first column of SciFi on the X<sub>FP</sub> location corresponding to E<sub>γ<sub>o</sub></sub>. Depending on β's departure from 12<sup>o</sup> the pivot point will be displaced from the focal plane. The spreadsheet calculates the (Δx, Δy) needed to return the pivot point to the focal plane and keep the first fiber column's longitudinal axis on the E<sub>γ<sub>o</sub></sub> electron's path. The spreadsheet's title for this is "Pivot Point Move" and the description is detailed below.
<center><b><u>For the next part we assuming the center of the first fiber column's front face is on the focal plane where an E<sub>γ<sub>o</sub></sub> post-bremsstrahlung electron will cross and the bundle support is placed at an angle β<sub>avg</sub></u></b></center>
<center><b><u>For the next part we assuming the center of the first fiber column's front face is on the focal plane where an E<sub>γ<sub>o</sub></sub> post-bremsstrahlung electron will cross and the bundle support is placed at an angle β<sub>avg</sub></u></b></center>
[[Image:Bundle_support_FP_shift.jpg|right|thumb|550px|Figure 22: Sketch showing the displacement needed to move the "pivot point" to the focal plane for β ≠ 12<sup>o</sup>, while maintaining the first fiber column on the E<sub>γ<sub>o</sub></sub> electron's path.]]
[[Image:Bundle_support_FP_shift.jpg|right|thumb|500px|Figure 22: Sketch showing the displacement needed to move the "pivot point" to the focal plane for β ≠ 12<sup>o</sup>, while maintaining the first fiber column on the E<sub>γ<sub>o</sub></sub> electron's path.]]
<li>Calculate the Y<sub>FP</sub> displacement required to place the focal plane back on the bundle support's pivot point, Figure 20</li>
<li>Calculate the Y<sub>FP</sub> displacement required to place the focal plane back on the bundle support's pivot point, Figure 20</li>
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Since
Since the post-bremsstrahlung electron's crossing angle changes with energy (e.g. displacement along the focal plane) each bundle support will have a slight "kick" or "tow" from the adjacent bundle support. Simply put, going from upstream [highest E<sub>γ</sub>] to downstream [lowest E<sub>γ</sub>], subsequent bundle supports will have smaller and smaller β<sub>avg</sub>'s.
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