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Scientists at the Department of Energy’s Oak Ridge National Laboratory have redefined traditional manufacturing methods, demonstrating the power of additive manufacturing in neutron experiments. The team faced a challenge, such as producing a 3D-printed collimator, a critical component in neutron scattering experiments, to filter out unwanted neutron background features.
Neutrons, like X-rays, are used to study energy and matter at the atomic scale. Collimators act as funnels, guiding neutrons toward detectors while minimising interference from stray neutrons scattering off non-sample elements. As experiments move towards smaller sample sizes in complex environments, precise collimation becomes paramount for filtering unwanted signals.
Working with ORNL’s Manufacturing Demonstration Facility, the team utilised binder jetting, an additive manufacturing process. This method, akin to printing on paper, builds parts layer by layer from powdered materials based on a digital design. Despite challenges in scaling up the collimator’s size for complex experiments, the team successfully demonstrated the viability of custom-built, 3D-printed collimators.
Initially, attempts to scale up the collimator by printing it as one large part failed due to the complexity of the process, leading to impaired precision. The team then developed an innovative “Frankenstein design,” printing multiple smaller parts with progressively tighter blades. This approach allowed for higher blade density and reduced channel sizes, overcoming the limitations of the printing process.
The team used advanced computational methods to simulate the experiment to optimise collimator performance, resulting in a design that could be directly produced without further engineering. The 3D-printed collimator was then tested on SNAP, a high-pressure neutron diffractometer, and successfully increased the relative sample signal over cell scatter, proving the concept’s effectiveness.
This research showcases the potential of additive manufacturing in neutron science, offering a new means of customising neutron scattering instrumentation. By combining modelling and advanced manufacturing, the team has paved the way for future advancements in neutron science, demonstrating the transformative impact of digital technology in scientific research.
The journey from concept to reality involved overcoming numerous technical challenges. One such challenge was maintaining accuracy while scaling up the size of the collimator. A larger collimator was necessary to capture more neutrons scattering from the sample and the complex pressure cell chosen for the test. In a pressurised environment, unwanted neutron scatter can dominate the weaker data signal, necessitating precise collimation.
“To demonstrate the viability of using custom-built, 3D printed collimators, we decided to use a tiny sample in a diamond anvil cell — a high-pressure chamber that uses diamonds to squeeze materials. Some of these cells are so complex and strong that they can produce pressures approaching those at the Earth’s centre,” said Bianca Haberl, the study’s corresponding author and a neutron scattering scientist.
The team encountered challenges during the printing process. Simply scaling up the collimator as one large part with continuous blades proved unfeasible due to variations in material contraction rates during curing and cooling. This led to cracking in the printed part, impairing its precision. Consequently, a new approach was developed to print multiple smaller parts and manually assemble them into a complete collimator.
The alternate-blade design with progressively tighter blades proved successful. This configuration allowed for a higher density of blades with reduced channel sizes and avoided size-related printing limitations. Ensuring the blades did not cross boundaries between individual parts made the design less sensitive to misalignment during assembly.
Employing this approach, the team optimised collimator performance through advanced computational simulations. These simulations enabled the development of a design that could be directly produced without further engineering. The 3D-printed collimator was then rigorously tested on SNAP, a high-pressure neutron diffractometer, where it exhibited extreme sensitivity to alignment, emphasising the necessity for ultra-high precision in manufacturing and positioning.
Once precisely aligned, the collimator increased the relative sample signal over cell scatter, validating the concept’s effectiveness. The study also identified areas for future refinement, including enhanced manufacturing quality control and alignment techniques.
The ability to customise collimators through additive manufacturing opens new avenues for researchers to explore complex scientific phenomena with greater precision and accuracy. Moreover, the study highlights the transformative potential of digital technology in advancing scientific research and innovation.
The Oak Ridge National Laboratory’s team has opened new frontiers in customising instrumentation for neutron scattering experiments by overcoming technical challenges and leveraging advanced manufacturing techniques.
This research not only enhances the understanding of fundamental scientific principles but also underscores the transformative potential of digital technology in driving innovation across scientific disciplines.
