Performance of a CsI(Tl) scintillation screen with a dual-periodic structure based on an oxidized silicon micropore array template in X-ray imaging

Preparation and performance of a CsI scintillation screen with a double-period structure based on an oxidized silicon micropore array template

A structured double-period CsI scintillation screen was successfully developed to improve its detection efficiency based on an oxidized silicon micropore array template with a period value on the order of micro-scale. The structure comprises a main structure along with a sub-structure. The main structure with a period of 8 µm was arranged in a square array consisting of square columnar scintillator units. The micropore walls between the main structure units were purposely fabricated from a SiO2-Si-SiO2 layered structure. The pore walls in commonly used single-structure with a period of 4 µm use the same layered structure composition to obtain a fair comparison. The thickness of both Si and the SiO2 layers was around 0.4 µm. The unique feature of the double structure lies in the even separation of each unit within the main structure into four square columnar scintillator sub-units. These four sub-units within each sub-structure were isolated solely by SiO2 layers with a thickness of approximately 0.8 µm. As a result, the X-ray-induced optical luminescence intensity of the double-structure screen exhibited a 31% increase compared to the corresponding single-structure scintillation screen. In X-ray imaging, a spatial resolution of 109 lp/mm was achieved, which closely matched the results obtained with the single-structure CsI screen. Furthermore, the detective quantum efficiency also displayed a notable improvement.

Ultrafast Decay, Ultrahigh Spatial Resolution, and Stable γ-CuI Single Crystal Treated by Iodine Annealing and SiO2 Coating

The demand for scintillators with ultrafast decay times, high spatial resolutions, and high stabilities is increasing due to the development of ultrafast hard X-ray detection, hard X-ray imaging, and high-energy physics facilities. γ-CuI single crystals, which exhibit ultrafast luminescence and high stopping power for hard X-rays, hold great promise for such applications. However, slow luminescence and poor stability caused by surface iodine deficiencies hinder the practical use of γ-CuI. Herein, we treated a γ-CuI single crystal by iodine annealing and SiO2 coating and investigated its crystal structure and luminescence properties in detail. Iodine annealing significantly enhanced the near-band-edge emission of the γ-CuI crystal with an ultrafast decay time of less than 1 ns, while completely suppressing the slow luminescence. Moreover, the SiO2 film effectively prevented the oxidation and decomposition of surface iodine, leading to substantial improvement in luminescence stability. The γ-CuI crystal demonstrated an ultrahigh spatial resolution of 1.5 μm in X-ray imaging, highlighting its potential for ultrafast hard X-ray imaging applications. This study provides insight into the growth, optimization, and application of γ-CuI crystals, advancing the field of scintillator materials.

Influence of the thickness of a SiO2 reflective layer on the performance of a structured CsI(Tl) scintillation screen based on an oxidized Si micropore array template in X-ray imaging

To obtain better light guidance and optical isolation effects under a limited microcolumn wall thickness, the influence of the thickness of a SiO₂ reflective layer on the performance of a structured CsI(Tl) scintillation screen based on an oxidized Si micropore array template in X-ray imaging was simulated. The results show that the SiO₂ reflective layer should maintain a certain thickness to achieve good light-guide performance. However, if the template is entirely composed of SiO₂, the light isolation performance of the microcolumn wall will be slightly worse. The results provide a basis for optimizing the thickness of SiO₂ reflective layer.

Influence of Si wall thickness of CsI(Tl) micro-square-frustums on the performance of the structured CsI(Tl) scintillation screen in X-ray imaging

To improve the detection efficiency of the structured scintillation screen with CsI(Tl) micro-square-frustums based on oxidized Si micropore array template in the case of a period as small as microns, the influence of Si wall thickness of the CsI(Tl) micro-square-frustums on the performance of the structured screen in X-ray imaging was investigated. The results show that when CsI(Tl) at the bottom of the screen is structured, the detective quantum efficiency (DQE) improves at almost all spatial frequency as the top thickness of the Si wall t_Si decreases. However, when CsI (Tl) at the bottom of the screen is not structured, the DQE becomes better at low-frequency and worse at high-frequency as t_Si decreases. The results can provide guidance for optimizing t_Si according to the comprehensive requirements of detection efficiency and spatial resolution in X-ray imaging.