Hi I am trying to simulate N particles evaporating from an oven, after which they propagate and eventually hit a wall. it is all classically, no quantum behavior. So far my approach has been the following: I pick a random Gaussianly distribution number, which I say is the velocity of the particle. Then the particle moves and hits the wall at some point. After a run I know how many particles have left the oven and how many atoms have hit the wall and where. I would like to refine my simulation, such that I know e.g. the flux of atoms hitting the wall. I'm not sure how to do this most properly, because ultimately I guess it requires for me to keep track of the time as well - which I am not doing currently. Can anyone give me a hint/suggestion to how I can do this? I would be very happy in that case. Best, Niles.