Simulation of atomic trajectories in the original Stern–Gerlach experiment

Following an analysis of the historical literature, we model the geometry of the original Stern–Gerlach experiment to numerically calculate the magnetic field using the finite-element method. Using the calculated field and a semi-classical model of spin, the propagation of the atoms in the beam is simulated to produce the well-known quantized end-pattern. Modeling the geometry of the magnets and the slits as faithfully as possible yields a two-dimensional pattern resembling the well-known postcard image sent by Gerlach to Bohr. The experimental parameters not reported in the original publications are 'reversed engineered' to adjust the length of the pattern.