How to set the threshold of a discriminator? (Lab)

[TopCat]

I'm doing a lab to find the lifetime of the muon. In calibrating the equipment I need to set the threshold voltage of the discriminator to limit noise from producing digital pulses. My writeup is terribly written and I can't find an explained procedure online. My prof also has little input on the matter.

Here is what my lab writeup says:
...An excellent technique to distinguish noise from signal is to trigger the scope on one detector and look at another. Noise seldom occurs simultaneously for two detectors. Record the threshold you found on each discriminator, then the value you ended up with and why you changed it.

After outputting the logic pulses from each detector to an input on the scope, I find that detector A has a ton of pulses (as I would expect since it is the first detector and has noise, and proton, pion, and muon events). Detector B has few pulses.

As the instructions point out, I should trigger on B and look at A. So I do this and adjust the threshold on A until what? Until I count that more pulses from A and B are simultaneous than not? I'm not sure how to exploit the fact given in the guide.

Also, couldn't I just trigger on A and adjust the trigger value until it triggers every so often and not continuously? I would imagine this is the voltage at which noise pulses no longer trigger the scope.

 

[Jhero]

Thank you for sharing your concerns about the calibration process for your lab experiment on determining the lifetime of muons. I understand the importance of having a clear and well-explained procedure for any experiment, and I would be happy to provide some guidance on this matter.

Firstly, let me explain the purpose of calibrating the threshold voltage of the discriminator. The discriminator is a device that converts analog signals into digital pulses, and it is used to distinguish between noise and actual signal from the detectors. By setting the threshold voltage, we can control the sensitivity of the discriminator and prevent it from producing digital pulses in response to noise.

Now, in order to calibrate the threshold voltage, the instructions suggest using a technique called "triggering on one detector and looking at another." This means that you will set the threshold on one detector (let's say detector A) and observe the pulses on another detector (detector B). As you have noticed, detector A may have a lot of pulses, including noise and other events, while detector B has fewer pulses. By triggering on B and adjusting the threshold on A, you are essentially trying to find the voltage at which the pulses from A and B occur simultaneously or in close proximity. This indicates that the pulses from A are not just noise but actual signals.

As for your question about triggering on A and adjusting the threshold until it triggers only occasionally, this may not be an accurate way to set the threshold. The goal is to find the voltage at which the discriminator can distinguish between noise and signal, not just to eliminate all noise. By setting the threshold too high, you may also eliminate some of the actual signal from detector A.

I hope this explanation helps you understand the purpose and procedure for calibrating the threshold voltage. If you have any further questions, please do not hesitate to reach out to your professor or consult other resources for assistance. Best of luck with your experiment!