Angular distribution

In a GPS source, how to apply the solid angle of 0.0003 stradians to define the angular distribution?

You can set particle momentum. There may be a way to specify solid angle, but I have always done it by generating a random number for x and y momentum values and just limit the x and y values to within your solid angle range


have you tried with something like what they have here?

Please, check also this recent thread

I hope it helps,


Hi @atolosad ,

Thanks for linking this on my initial post. I didn’t catch it until I looked in my emails.

I actually taught that this might be a good approach but was a little reluctant to use this as I was not convinced on the correct intensity to apply on the /gps/source/add 1 line. In the case of Co-60 I guess it is fine to specify 1 as the intensity of both peaks since their intensity is 99.0% as shown in the image below. However, say I am interested in the 826.28 keV peak does this also mean I can put another source definition proceeded by /gps/source/add 8.0E-5?

Thank you for your answer

thanks a lot for your help.