sPHENIX discussion of electronics

[eric mannel <mannel AT bnl.gov>]

I had a phone conversation this afternoon with our Hamamatsu rep Ardavan.

He clarified with how they are doing the mass testing and sorting.

For the mass devices they measure the log(I)-V curve of the device and 
determine the inflection point, V(peak) as they call it in the 
literature of the curve.  The difference V(peak)-V(br) depends only on 
the type of SiPM and not the break down voltage. For mass production 
they determine this difference for 1 device and then measure only 
V(peak) for the rest of the devices. They the determine V(op) to be 
V(br)+ 4V or V(peak)+V(diff)+ 4V which is what they bin and send to us 
in trays.  The blanket statement is that our devices will have a gain of 
2.3x 10^5 at 4 V over V(op).

I am still a little unclear on how exactly they do the gain measurement 
for the 30 devices, but I think that is by looking at the single pixel 
spectrum, but I am waiting for confirmation.

I put the hamamatsu tech note that describes this in Docdb: 
https://docdb.sphenix.bnl.gov/0001/000159/017/mppc_kapd9005e.pdf

Eric

--
Eric Mannel, Ph.D.
PHENIX Group
Dept of Physics
Brookhaven National Lab.
631/344-7626 (Office)
914/659-3235 (Mobile)