Muon angular distribution from CRY

Hi All,

I have managed to integrate the cosmic-ray library (CRY) into Geant4 and have run some first tests but it seems that the zenith angle distribution returned is incorrect. I seem to not be seeing a cos^2 distribution as expected. Does anyone have any ideas about this or has anyone experienced the same issue?

Screenshot from 2020-08-24 15-28-12

Best regards,

Dear Sarah,
If the problem is not already answered then this may help, otherwise it will be helpful to others in future.

If you just plot the zenith angle distribution taking cosmic muons from CRY, then i believe you must be calculating the angle between the vertical down (0,0,-1) and the direction in which the particle is coming from CRY. From detector point of view you are actually considering that your detectors are lying horizontally, hence there is no solid angle correction applied. So if you want to see the fitting with cos^2 distribution then you have to apply solid angle correction, and then the fitting with m*cos^n will give the value of n close to 2.

Hope it clarifies your doubt.

If you had already got the correct distribution then it will be good if you post your solution also , because that will help others.


Hello! How do you ensure that CRY outputs all the particles that can reach the detector you set up?Since CRY emits a lot of particles in its simulation of the real sky, Not all of these particles are what they want. How do you get all of CRY’s particles to the detector?

So far, many of the particles in my simulation that don’t fit the criteria still occupy the output of Eventid. In this case, if I want to get a certain number of particles to reach the detector, I have to shoot a lot more than that number of particles to get the data I want from it, which is very troublesome because there is a finite number of particles that Geant4 can emit.