From: Marc Dejardin [marc.dejardin@cern.ch]
Sent: 10 December 2008 10:39
To: Alexander Ledovskoy
Cc: Dave Cockerill; Giovanni Franzoni
Subject: PN cabling for EE

Attachments: MEM_BOX_Dee_last.xls

Hello Sasha,

I would like to give you some more details on PN actual cabling on EE.
We would not like to enter in too much details during the DPG meeting, but what should have been
said during this meeting is that we have PN measurement to compute VPT/PN for each monitoring region
and each diffusing sphere.

The point is that for some diffusing sphere, we had to cheat...

There are indeed cabling problems at the EE patch panel (or DMEM patch
panel) and some L1 PN are not connected to read-out channels of the DMEM. We have instead L2 PN.
So for the corresponding diffusing spheres (which have no direct reference PN data in the read-out) 
we are using PN data from neighboring harness which is illuminated by the same mother fiber.
At first order it works, even if it is not a solution for long term.

Concerning the LED, it is more problematic, because you are directly injecting light in the diffusing sphere.
So for these problematic harnesses, you don't have any reference PN data.

This is why we want to correct the cabling for next year.

I join a file in which you can find the theoretical and real cabling (PN ref tab) of EE on End-caps. 
We expect to have the theoretical cabling for all Dees after corrections. For the moment only Dee1 is 
not far from the theoretical cabling.

Best regards
Marc