[Dsg-rich] RICH temperature/humidity sensor cable feedthroughs light-tightness test

[Tyler Lemon]

Hello Marco Contalbrigo, 

Peter mentioned yesterday morning that there are concerns that the feedthroughs Sandro and Dario have for the Hardware Interlock System's temperature and humidity sensor cables would not be light-tight. 

To determine if the feedthroughs would be light tight, we used a photodiode and the darkbox from the reflectivity test station. 

The feedthrough and cable were put into the side of the darkbox with the feedthrough tightened around the heat shrink that is on the test cable. The attached photos show how the feedthrough was fastened to the darkbox and how the cable passed through the feedthrough. 

Photodiode currents were recorded for two cases: 
Case 1.) Darkbox with cable through feedthrough and no light directly on feedthrough 
Case 2.) Darkbox with cable through feedthrough and flashlight directly on feedthrough 

Measurement results are in the attached "feedthrough light test 2017-08-07.xlsx". 

Comparing the results from Case 1 and Case 2, there is a difference in the amount of light measured by the photodiode. There is approximately 4% more light measured with a flashlight shining directly on the feedthrough than with no light on the feedthrough. 

Is this acceptable for the light-tightness of the feed-through with the cable? 

If not, we could: 
1.) add another layer of heat shrink to make a tighter fit between the feedthrough and cables 
2.) fill gaps between cables inside heat shrink with some type of epoxy or caulk 
3.) permanently glue the cables into the feedthrough with an epoxy or caulk 


Best regards, 
Tyler 
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