Influence of preparation process on the transparency of CsI microcolumns in the structured CsI scintillation screen based on oxidized silicon micropore array template

Abstract

The structured CsI scintillation screens based on oxidized silicon micropore array templates can maintain high spatial resolution in X-ray imaging while increasing their thickness. However, the detection efficiency of the screens is not only related to their thickness, but also related to the transparency of the CsI scintillation microcolumns in the screens, because it affects the output of the scintillation light. In this work, the hexagonal array arranged structured CsI scintillation screens based on oxidized silicon micropore templates with pore pitch about 4.3μm and diameter about 3.0μm were fabricated by vacuum melting and pressure injection method. In order to improve the transparency of the CsI microcolumns, the effects of filling temperature and pressure on the morphology, crystallinity, X-ray excited optical luminescence (XEOL) and transparency of the CsI scintillation microcolumns were studied after a preliminary research on TG-DSC, melt viscosity and bulk preparation of CsI material. The results show that with the increase of filling temperature, the cracks and microbubbles in the filled CsI microcolumns become less or even disappear under the filling pressure of 6 MPa, and the crystallinity of the microcolumns becomes better. Meanwhile, the intensity of the XEOL becomes stronger. The light attenuation coefficients of the CsI scintillation microcolumns prepared at different filling temperature were derived by Geant4 Monte Carlo simulation toolkit according to the results of XEOL. The light attenuation coefficient decreases significantly as the filling temperature increases. When the filling temperature reaches 660 °C, the light attenuation coefficient of the CsI microcolumns has dropped below 0.002μm−1. Such a low light attenuation coefficient is completely suitable for X-ray imaging of the structured high-resolution CsI scintillation screens based on oxidized silicon micropore array templates that have been developed.