Plastic scintillator detectors are used extensively in high-energy physics experiments because they are cost-effective and enable sub-ns particle tracking and calorimetry. The next generation of plastic-scintillator detectors aims to instrument large active volumes with a fine 3D segmentation, raising major challenges for both production and assembly. One example is the two-tonne “super fine-granularity detector”, an active target made of two million 1 × 1 × 1 cm3 scintillating cubes at the T2K neutrino experiment in Japan. Scaling up this intricate workflow or aiming for more precise segmentation calls for technological innovation.
Enter the 3DET (3D printed detector) R&D collaboration at CERN. Also involving ETH Zurich, the School of Management and Engineering Vaud in Yverdon-les-Bains and the Institute for Scintillation Materials in Ukraine, 3DET is advancing additive-manufacturing methods to create plastic scintillator detectors that do not require post-processing and machining, thereby significantly streamlining the assembly process.
The 3DET collaboration has now passed a major milestone with a completely 3D-printed monolithic detector comprising active plastic scintillator cubes, the reflective coating to make the cubes optically independent, and the holes to insert wavelength-shifting optical fibres through the whole structure. Without the need for additional production steps, the prototype can be instrumented with fibres, photocounters and readout electronics right after the printing process to produce a working particle-physics detector. The team used the device to image cosmic rays with a scintillation light yield and cube-to-cube optical separation of the same quality as state-of-the-art detectors, and the results were confirmed with beam tests at the T9 area.
“This achievement represents a substantial advance in facilitating the creation of intricate, monolithic geometries in just one step. Moreover, it demonstrates that upscaling to larger volumes should be easy, cheaper and may be produced fast,” write authors Davide Sgalaberna and Tim Weber of ETH Zurich. “Applications that can profit from sub-ns particle tracking and calorimetry in large volumes will be massive neutrino detectors, hadronic and electromagnetic calorimeters or high-efficiency neutron detectors.”
