J. Weinacker, S. Kalt, A. Huber, N. Gutknecht, J.L.G. Schneider, N.M. Bojanowski, T. Geigle, M. Steidl, and M. Wegener

Adv. Funct. Mater. (2024); doi:10.1002/adfm.202413215

Abstract:

Plastic scintillators are inexpensive to manufacture and therefore a popular alternative to inorganic crystalline scintillators. For many applications, their advantages outweigh their lower light yield. Additionally, it is easier to structure plastic scintillators with well-developed processing techniques which is of growing relevance in modern applications. One technique to structure plastic material is 3D printing, with noteworthy recent advances in one-photon-based approaches. However, some applications require high spatial resolution and optically smooth surfaces, which can be achieved by multi-photon 3D laser micro-printing. One application example is the improvement of sensitivity of the Karlsruhe Tritium Neutrino (KATRIN) experiment. This improvement can be realized by printing a 3D scintillator structure as an active transverse energy filter directly onto the detector. Herein, the first two-photon printable plastic scintillator providing a printing resolution in the micrometer regime is presented. Using the benefits of two-photon grayscale lithography, optical-grade surfaces are achieved. The light output is estimated to be 930 photons MeV⁻¹. A prototype structure printed directly on a single-photon avalanche diode array is demonstrated.