Computational optimization of a 3D printed collimator

Abstract

This contribution describes the computational methodology behind an optimization procedure for a scattered beam collimator. The workflow includes producing a file that can be manufactured via additive methods. A conical collimator, optimized for neutron diffraction experiments in a high pressure clamp cell, is presented as an example. In such a case the scattering from the sample is much smaller than that of the pressure cell. Monte Carlo Ray tracing in MCViNE was used to model scattering from a Si powder sample and the cell. A collimator was inserted into the simulation and the number and size of channels were optimized to maximize the rejection of the parasitic signal coming from the complex sample environment. Constraints, provided by the additive manufacturing process as well as a specific neutron diffractometer, were also included in the optimization. The source code and the tutorials are available in c3dp (Islam (2019)).

Second Target Station (STS) Project: PIONEER Technical Report

“…We plan to use a similar design to the one used at ARCS [19] and multiple other beamlines, including CORELLI and POWGEN. For the bottom flat detector, we plan to design a 3D-printed conical collimator [20,21]. Figure 2-17 shows the ARCS collimator, the 3D-printed B4C collimator made at ORNL, and the proposed bottom detector array with a 3D-printed collimator.…”

Second Target Station Instrument Systems Research and Development Plan

“…Figure 3: A complex, conical geometry collimator computationally designed from an algorithm written by Fahima Islam (Islam et al, 2020). The left side shows the complete, printed device and the right shows a cross section.…”

“…As an example, additive manufacturing provides the designer of a collimator the freedom to choose a geometry to favor a weakly scattering sample while suppressing Bragg peaks from a strongly scattering sample environment or other material which may be present on an instrument. The collimator in Figure 3 was designed exactly for this purpose (Islam et al, 2020). Sample sizes at the STS will typically be an order of magnitude smaller than at SNS, requiring more complex collimators with finer features that would be difficult, impossible, or prohibitively expensive to manufacture using conventional methods.…”