[Vetroc_daq_sbs] ADC

[R. Evan McClellan]

Thanks Carlos!

I'll meet you out at ESB tomorrow.

-Evan


----- Original Message -----
From: "Carlos Ayerbe Gayoso" <gayoso at jlab.org>
To: "Vetroc_daq_sbs" <vetroc_daq_sbs at jlab.org>
Cc: "Todd Averett" <tdaver at wm.edu>
Sent: Wednesday, October 12, 2016 6:05:02 PM
Subject: [Vetroc_daq_sbs] ADC

Hi guys,

I'm embarrassed to say this, I think I got coincidences between PMT signal and the trigger, but I have no idea what I did. I was playing with different sets on the pulser unsuccessfully and then I press the button to center the signals in the oscilloscope and then there appear the coincidence. Not clean, some reflections, but definitely coincidences. 

I introduced more delay in the signal, 500ns and it is quite good. I shortened some cables for the trigger signal.   

-DS000101.png coincidence signal triggering on the gate
-DS000102.png coincidence signal triggering on the gate, different scale on signal
-DS0001.png coincidence signal triggering on the signal. 
-DS0002.png coincidence signal triggering on the signal threshold ~14mV
-DS0003.png  coincidence signal triggering on the signal threshold ~14mV horizontal scale changed, LED disconected

you can notice those huge signals, they don't come the LED as you can see on DS003. Right now, no idea where they come from (cosmics?)

I estimate there is around 30ns from gate to the riding edge of the signal, but consider that this is the output from the discriminator, this signal is carried to the ECL-NIM converter and the with twisted pair cable to the gate entry. This cable measures 20 ft. Assuming same delay as coaxial cable, we have ~30 ns delay introduced in the gate. 

The pulser settings:

HIL: 4V 
PER: 250us
WID: 9ns

I noted that there are some configurations in the pulser that change the width of the trigger signal (the one from the pulser to channel 112).

Well, I'll try to take data and see how to improve the set up.

FYI, I'll come to JLab tomorrow Thursday, I have a meeting at 10am, then I'll come to ESB. I'll have the Owl shift that night, so on Friday, I'd like to stay no longer than midday. 

Cheers

-Carlos
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