PRA - how do I get the right channel?

[pietkuip]

In PRA, I cannot get input from the right channel now. It is not a hardware problem, I think, because the Audio Input window does not even show a blue line at all (it does show the red trace for the left channel, and the yellow and brown threshold lines). This does not change when I select the Right channel or Right if Left etc.

I know that I struggled with this problem before. I know that I solved it, because I did manage to take coincidence spectra. The stupid thing is that I do not remember how :(

[Sesselmann]

Pieter,

Try Settings >> Audio interface >> Left and Right

Also you will need to make up a stereo to two mono jack plugs adaptor.

Screen Shot 2015-05-14 at 7.33.36 am.png

[pietkuip]

Thanks! But I am happy to say that the student found this out himself. The coincidence works fine now with the annihilation peak. We are using two passive low-pass filters for that. Resolution is degraded with respect to GS, but still good enough to see resolved peaks.

He is now going on to look for gamma cascades. Coincidence with the soundcard makes it easier to do nuclear physics: looking at the level schemes, trying to understand where these peaks are coming from instead of just fingerprinting for identification.

[Nephrondoctor]

Hi Pieter,

How did you manage to perform coincidence measurements with GS1100. Can you send me a scheme of your setup ?
Thank you very much. Alfred Apperloo, the Netherlands, nephron at home.nl

[brehwens]

Alfred,

I believe you need two detectors/drivers (of course) but also a "combiner" for the audio, merging the two mono outputs (Left and right) into a single 3.5 mm audio jack into the computer, so it can capture each detector on its own channel.

[pietkuip]

Yes, we did it the way Carl describes it. We have several detectors but right now I have only one GS available (we will get more). My student wanted to test if he could combine it with the low-pass filter (see Prutchi). And yes, that works, despite the differences in timing. (Although he said that the number of coincidences was sensitive to threshold settings. Positive or negative for the GS channel causes a delay).

[Nephrondoctor]

Carl and Pieter, thanks for your replies. I own David Prutchi's book, I will take a look. Alfred