[Halld-cal] Draft of BCAL constants document

[Elton Smith]

Dear colleagues,

I have uploaded a draft document (GlueX-doc-2618) with definitions for 
the low-level calibration constants for the BCAL. This is a document for 
discussion and feedback is welcome. The goal, after we have hashed it 
out, is to have precise definitions of all constants that are placed in 
the calibrations data base. In particular, it is necessary to choose 
some conventions, which need to be clear to avoid errors in 
reconstruction. We need to agree on what those conventions are. We 
should also make sure that there are no factors of 2 missing.

The document proposes that the gains be specified at the center of the 
module.  If I understand correctly, this is different than Andrei's 
convention that uses the end of the module.
Therefore, there is a factor of e^{-L/2*lambda} between the two that 
needs to be sorted out. There may also be other definitions or 
conventions that need consensus.

We should probably find a dedicated time to go over this. As we are in 
the process of entering constants into db now, I would hope to have a 
discussion soon. Is Friday a possibility?

Thanks, Elton.


-- 
Elton Smith
Jefferson Lab MS 12H3
12000 Jefferson Ave STE 4
Newport News, VA 23606
(757) 269-7625
(757) 269-6331 fax