CPR2 Optical Cables
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Transcript of CPR2 Optical Cables
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CPR2 Optical CablesJoey Huston
Michigan State University
…taking optical signals from edgeof CPR/crack detectors to PMT boxes mounted on backof wedges
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Optical cables
Optical cables ~3-5m long take optical signals to PMT boxes mounted on back of wedges diameter of clear fiber
steps up to 1.1 mm in order to reduce alignment issues
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Routing
Clear fibers are routed into 4 connectors of 16 channels each
– connector D has 6 fibers from CPR and 10 from crack detector
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Light-tighting
Black plastic covering for optical cable
Sliding plastic shroud for connector region
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Clear fiber attentuation length
Clear fiber tests conducted at Rockefeller
Attenuation length best fitted to 2-components
PolyHiTech and Kuraray give similar results
PolyHiTech used for cables
1000 m of Kuraray purchased for spares
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Optical cable installation issues
Main Installation Issue for Preshower/Crack. Length of cables is at best an educated guess.
Need full scaffold and PMT boxes installed to measure best lengths. extra 50 cm of cable causes 10% loss of light yield,
and is a good place to cause fiber damage. PMT box placement changes depending on
wedge, and complete plan changed 4 times in last long access.
Plan is to make 50% of the optical cables before shutdown with educated guess, then after first week of shutdown make the rest (takes about 1.5 weeks per arch).
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Determine step-by-step the additional lengths to add to these straight-line paths for optical cables.
Determining cable lengths
Approximate distances to add to the clear
fiber lengths (for normal wedges)
110 mm -- middle of wedge to farthest CPR connector
205 mm=8” -- distance across side window on wedge
915 mm=36” -- horizontal distance across wedge to PMT box
305 mm=12” -- vertical distance to PMT box
305 mm=12” -- lateral distance to PMT box
150 mm -- safety margin (?)
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Step 2: The window height is known to be 8”, and the cables must enter the back of the wedge from the farther point on the window. Assume a straight line from the middle point on bottom of window to middle point on top of window. 8” = 205 mm
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Electronics crate
Signal and HV cables
Optical cables
Black LED fibers for EM Cal
PMT access
3’ to middle
Step 3: 3’ from entry point at window to middle of plate holding PMT boxes. 3’ = 915 mm
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Step 4: Plate that box sits on could be as high as 6”. Top cable for the box is about 6” high. So add about 12”=305mm for a vertical rise from the base of wedge to the PMT box.
Step 5: Optical cable entry point in the window will likely not line up with PMT box hole. Assume a 12”=305mm travel across wedge for this.
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Tight spots
Tight fit in last long access!
Scraped sides of connector
on 1 arch, fine on the other
arch. MSU has since trimmed
connector by 1.5 mm.
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4 PMT boxes mounted on sides of monkey bars
2 PMT boxes mounted on inside of cradle
6 PMT boxes mounted on “normal” wedges