[Halld-pid] Start Counter "warming"

[Fernando Barbosa]

Hello Beni,

Looking at the plots, I agree with your assessment of significant gain degradation. However, I am a bit dubious that the gain can be recovered by that much via annealing. This will be an interesting test.

Best regards,
Fernando 

-----Original Message-----
From: Fernando Barbosa <barbosa at jlab.org> 
Sent: Tuesday, October 31, 2023 8:12 AM
To: Benedikt Zihlmann <zihlmann at jlab.org>; halld-pid at jlab.org
Cc: Fernando Barbosa <barbosa at jlab.org>
Subject: RE: Start Counter "warming"

Hello Beni,

I suggest 40 to 60 degree C and 1 month of annealing should provide considerable recovery. I would also suggest keeping the bias off.

Best regards,
Fernando

-----Original Message-----
From: Benedikt Zihlmann <zihlmann at jlab.org> 
Sent: Tuesday, October 31, 2023 7:20 AM
To: halld-pid at jlab.org; Fernando Barbosa <barbosa at jlab.org>
Subject: Start Counter "warming"

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