Hong Joo Kim | 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

Constraints for rare electron-capture decays mimicking detection of dark-matter particles in nuclear transitions

We give for the first time, theoretical estimates of unknown rare electron-capture (EC) decay branchings of $^{44}$Ti, $^{57}$Co, and $^{139}$Ce, relevant for searches of (exotic) dark-matter particles. The nuclear-structure calculations have been done exploiting the nuclear shell model (NSM) with well-established Hamiltonians and an advanced theory of $β$ decay. In the absence of experimental measurements of these rare branches, these estimates are of utmost importance for terrestrial searches of dark-matter particles, such as axionic dark matter in the form of axion-like particles (ALPs), anapole dark matter, and dark photons in nuclear transitions. Predictions are made for EC-decay rates of 2$^{nd}$-forbidden unique (FU) and 2$^{nd}$-forbidden non-unique (FNU) EC transitions that can potentially mimic dark-matter-particle detection in dedicated underground experiments designed to observe the absence of the corresponding nuclear electromagnetic transitions.

nucl-th↗