The fiber and trigger PMT's were fastened on a dexion support stand, and each fiber ribbon was mounted on a 2x4 piece of lumber which was nailed onto a 4 m long 4x4 piece that was positioned at beam height. The 4x4 was moved progressively past the beam focus to put the appropriate spot of the fibers in the beam for our length scan, in order to extract the attenuation length. This process allowed for a robust coupling of the fibers to the PMT's.
With its axis oriented at an angle of 90 with respect to the
beam, the fiber bundle was placed between a large paddle counter (PR)
and a finger counter (TR) 1 cm wide and 4 cm in height, as depicted in
Figure 5. Two additional counters (PF and PD)
were placed immediately after the beam pipe vacuum window and at the
back wall of the area, spaced 413 cm apart. Photographs of the
experimental setup are shown in Figure 5.
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