Gain suppression studies on nLGAD detectors

Detecting low-penetrating particles in silicon, such as soft X-rays, ultraviolet light, or low-energy charged particles, is fundamental for a wide range of applications in both industry and research. The nLGAD (n-type Low Gain Avalanche Detector) is considered a good candidate for that, as it potentially combines high sensitivity with excellent timing performance, while avoiding the excess noise of conventional Avalanche Photodiodes (APDs), which are not optimized for precise timing measurements. However, further investigation is needed to fully understand nLGAD performance in different detection environments and background irradiation conditions. This work presents the first results of gain suppression effects in nLGADs when illuminating with low- and high-penetrating photons with wavelengths of 404 nm ( ≈ 0.1 µm absorption length in silicon) and 1064 nm ( ≈ 1000 µm absorption length in silicon), as well as their dependence on the actual photon density of the beam sources. Additionally, the nLGAD gain after moderate levels of proton irradiation are also studied for low-penetrating 404 nm wavelength photons. The results confirm that nLGADs maintain a moderate gain under these conditions, confirming their suitability for detecting low-penetrating photons even after irradiation.