CPR2 Optical Cables Joey Huston Michigan State University …taking optical signals from edge of CPR/crack detectors to PMT boxes mounted on back of 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