Scattering experiments (e.g. the gold foil experiment) are important research tools of nuclear and particle physics. They help us to study interactions between particles and to obtain information about the structure of matter. Below, we present activities using a mechanical 3D-printable scattering experiment. The activities include different difficulty levels, in which high-school students can study scattering qualitatively, semi-quantitatively or quantitatively.

If you don’t have access to a 3D printer, you can also rebuild the setup with everyday equipment such as marbles, tennis balls and cardboard.

The 3D-printable setup

We developed a 3D printable model for a mechanical scattering experiment with 5 mm steel balls (ball bearings). This setup includes

base (a): a circular base plate with a diameter of 18 cm and 16 pockets to collect the scattered steel balls
ramp (b): a ramp for 7 steel balls of 5 mm diameter, with a distance of 7 mm. The beta version of the ramp provides 3 different starting positions at a different height to modify the kinetic energy of the steel balls
scattering objects (c): including a circular cylinder (diameter 4 cm), triangular prism (side length 3.5 cm), 1/r potential hill (max. diameter 3.5 cm), cuboid (side length 3.5 cm) and an object with a substructure (3 small circular cylinders, each 1 cm in diameter)
lid (d): can be attached to the scattering objects to hide them underneath
steel balls (e): need to be purchased separately, diameter 5 mm, look for a shop selling ball bearings
Suggestions for educators

There are different ways to use this scattering model in your classroom. Depending on the age and level of your students, we propose 3 different difficulty levels. In any case, it is important to discuss the limits of this mechanical scattering model when comparing it to the goal-foil experiment.

Qualitative approach: The scattering patterns are interpreted only qualitatively. Students get to see the different scattering objects beforehand. Then, one of the students or the teacher hides one of the objects under the lid. After observing the scattering angles for a few steel balls, students try to guess the shape of the hidden object. This activity can be used to highlight the difference between observation (the scattered steel balls) and inference (the conclusion we draw based on our observation, in this case, the shape of the scattering object) in science. However, in real life, we have no way of “lifting the lid” to confirm our hypotheses. Instead, we can only design new experiments to test our hypotheses. Here, the role of models in scientific research can be discussed. In this version of the activity, we suggest starting without the 1/r potential hill. In the end, the teacher can use the potential hill to highlight the difference between mechanical scattering objects and Coulomb scattering potentials.