[Halld-pid] Start Counter "warming"

[Beni Zihlmann]

Hi Fernando, Werner,

in view of the fact that we do see a significant degradation in the gain 
of the Start counter
response over the years I was thinking if active "annealing" may help.
see also:
https://halldweb.jlab.org/wiki/index.php/Start_Counter_Operations#Run_Period_Winter_2023

It is not clear why this drop in gain occurred. It does not seem to be 
related to a loss in light
since the ration of width divided by mean-amplitude has not changed 
much, and in the nose
area not at all (this is the middle histogram of the plot). So the 
source of the loss in gain may
be related to the SiPM photo sensor itself?

We know "annealing" helps with regards to dark current but I am not 
aware of recovering gain.
An active annealing can be employed by covering the photo sensor area 
with a "heating blanket"
and warm up the region to a certain temperature. The question is what 
temperature can be
considered "save" with regards to the PCB board and electronics as well 
as the plastic scintillators.

how high in temperature do you think can we go without affecting these 
parts? 70 degree Celsius
or even more?
The time frame for such an "annealing" attempt would be of order 1 month.

any comments?

cheers,
Beni