Nguyen Duc Ton | Searcharxiv

arXiv2026

Development and characterization of the efficient portable X-ray imaging device based on Raspberry Pi camera

This study reports the development and characterization of an efficient portable X-ray imaging device built from Raspberry Pi components, including a high-quality 12.3-megapixel camera configured for indirect detection with a Gd2O2S:Tb scintillation screen. The device was evaluated under both ambient light and X-ray exposure conditions. Initial characterization under ambient light ensured proper optical focusing; subsequently, camera settings (ISO and exposure time) were evaluated and optimized for X-ray imaging performance. Spatial resolution of the developed device was quantified using the Slanted-Edge method to derive the Modulation Transfer Function (MTF). Besides the low-noise feature, the device achieves MTF20 values of 68 lp/mm under ambient light and 25 lp/mm under X-ray irradiation (50 and 70 kV). Moreover, the modularity of the developed device was confirmed by conducting the tests with LYSO:Ce and GAGG:Ce screens. The results demonstrate that this efficient, scientific-grade, compact platform achieves spatial resolution comparable to that of clinical radiography systems, highlighting its potential for applications in scientific, educational, and medical contexts where efficient and portability are critical considerations.

physics.ins-det↗

arXiv2024

Absolute light yield measurement of NaI:Tl crystals for dark matter search

The NaI:Tl crystals were early investigated and used for wide application fields due to high light yield and crystal growth advantages. So far, the absolute light yields of NaI:Tl crystal have typically been known to be 40 ph/keV. However, it varies widely, far from the theoretical estimation. Since the high light yield and better sensitivity of NaI:Tl crystal is important for low mass dark matter search. Therefore, it is necessary to use high light NaI:Tl crystal, and absolute light yield should be measured with accuracy. In this work, we use the single photoelectron technique for measuring the absolute light yield of 35 NaI:Tl crystals with various sizes from different vendors. There are several high-quality crystals from the COSINE-100 experiment and commercial companies in these crystals. The theoretical estimation and GEANT4 optical simulation have been studied to investigate the PMT optics. Results show the essential role of this correction in avoiding overrated light yield values. The SPE technique using different PMT was compared to the photodiode and avalanche photodiode methods. A 10% systematic error was obtained. Our results show the excellent absolute light yield of NaI:Tl, at 59.4 +- 5.9 ph/keV, while the theoretical predicted light yield is around 70 ph/keV. The evaluation with NaI:Tl crystals in the COSINE-100 experiment has been performed. The six crystals in the COSINE-100 experiment have a high light yield. Based on our results, the light loss of encapsulation needs to be improved, especially for the big-size crystals.

hep-ex↗