For a neutron imaging process, the neutron beam coming from the source should be focused to a desired size. Aperture systems consisting of one or more slit systems are the industry standard for this purpose.

The problem arises in respect to very small slit widths required, which is very difficult to produce with a CNC milling machine. Likewise, the decision to use 3D printing meant that the edges of the slit needed to be finished very sharply. This is crucial for the quality of the neutron images in experiments. The picture on the right shows three different B4C (black) slit apertures with openings of 0.7, 0.5 and 0.25mm. For an optimal installation on the beamline, the housing was printed from PA12CF and has a very high stability due to the carbon fiber.

In a test series to increase the print quality compared to the B4C filament, we designed a filament based on boron nitride (white aperture). This shows excellent printing properties. The aperture thickness was increased in contrast to the boron carbide in order to realize the same attenuation of the neutron beam.

Multi-use and interchangeable aperture systems are an ongoing development and is expected to continue in 2023.