[Halld-cpp] TAC detector signal test

[Beni Zihlmann]

Hi All, (second try with out attachents)

find the pictures here:
https://halldweb.jlab.org/talks/2022/CPP_NPP/
TAC_signal1.png, TAC_signal2.png and TAC_signal3.png


I had a look at the TAC signal right at the input to the fADC250.
This is located in channel 0, slot 20, D2-3-TOP

HV used is channel 20, module 14 (double slot size), D2-8-TOP. The 
channel in the module is labeled "TAC".

HV = -1700V drawing about 585uA. The trip limit is set at 1000uA.

attached you find 3 pictures of a scope shot for documentation.

The noise level is very low, smaller than 0.5mV. There is a clear but 
very small 50Hz baseline modulation visible
at the level of about 0.4mV peak to peak.->TAC_signal3.png

The signal itself has a rise time of about 3ns and a decay time of about 
8ns (both 10% to 90% and 90% to 10% respectively).
With a trigger threshold at 10mV the rate is very small way below 1Hz. 
->TAC_signal1.png
Higher trigger rates, 10Hz or more (my estimate), is seen with very low 
trigger threshold (less than 1mV). -> TAC_signal2.png


Based on these observation the detector looks operational working quite 
nice. These tests can however not assess the
functionality at high rates.

cheers,