sPHENIX HCal discussion

[Achim Franz <afranz AT bnl.gov>]

Hello, 

checking my simulation macro for the diagonal fiber arrangement I found what 
I was suspicious of, I had one of the light sources placed not centered 
inside the fiber, so the light went all over the place explaining the low 
efficiency and odd distribution. Now that it is fixed I do see the strong 
peaks from the fibers here too. Attached is a set of slides showing the light 
distribution on the SiPM from 0.1 to 3.0 mm distance for a black box, i.e. NO 
wall reflection. 
The first two slides shows a summary of the fraction of light that makes it 
onto the SiPM, the ratio of minimum versus maximum count, and what the 
program calls R.M.S Uniformity.
The following slides are then the intensities on the SiPM for the different 
distances on the same z-scale.

I can run the same for the parallel fibers to see if there is a difference. 
In case you are confused about diagonal versus parallel fiber configuration, 
look at my Atlanta presentation.

Achim

Attachment: SmallDistances.pdf
Description: Adobe PDF document