Hi Say I have a container (e.g. an oven) with some atoms in it. It the container, there is an opening, from which the atoms go into a rectangular container and then continue to the rest of the experiment. The beginning of my setup is shown in the attached sketch. My problem is that I wish to find the transverse and longitudinal velocity distribution of the atoms leaving the oven. I am pretty sure that the longitudinal velocity is given by a Maxwell distribution, which in turn deoends on the oven temperature. However, how is the transverse velocity distribution given for such a system? Best, Niles.