cpr2 optical cables
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CPR2 Optical Cables. …taking optical signals from edge of CPR/crack detectors to PMT boxes mounted on back of wedges. Joey Huston Michigan State University. Optical cables. Optical cables ~3-5m long take optical signals to PMT boxes mounted on back of wedges - PowerPoint PPT PresentationTRANSCRIPT
CPR2 Optical CablesJoey Huston
Michigan State University
…taking optical signals from edgeof CPR/crack detectors to PMT boxes mounted on backof wedges
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
Routing
Clear fibers are routed into 4 connectors of 16 channels each
– connector D has 6 fibers from CPR and 10 from crack detector
Light-tighting
Black plastic covering for optical cable
Sliding plastic shroud for connector region
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
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).
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 (?)
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
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
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.
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.
4 PMT boxes mounted on sides of monkey bars
2 PMT boxes mounted on inside of cradle
6 PMT boxes mounted on “normal” wedges