Wide Energetic Response of 4π Directional Gamma Detector Based on Combination of Compton Scattering and Photoelectric Effect

Directional information is crucial in various applications, such as nuclear homeland security (HLS), post-nuclear and radiological contamination mapping, and space missions. The energy range of interest is expected to include industrial radionuclides starting from low energies, such as 241Am and up to 60 Co. However, many directional radiation detectors often relied on directional shielding, made of lead or tungsten, introducing two main drawbacks. First, their size and weight render them unusable for handheld devices, drone mapping, and space applications. Second, their limited field of view (FOV) necessitates either multiple detectors or rotation machinery to cover the whole required FOV. We present a novel 4π directional detector based on a segmented hollow cubic design. For the low-energy range, we use the photoelectric effect with mutual collimation, eliminating the need for heavy collimators and ensuring that all the interactions are measured, resulting in higher efficiency. For the mid- and high-energy ranges, the detector utilizes the Compton effect interactions. Instead of employing traditional scatterer and absorber detectors, we employ a unified detector based on a Gd₃Al₂Ga₃O₁₂ [GAGG(Ce)] scintillator coupled to a silicon photomultiplier (SiPM). The symmetrical cubical design provides both high efficiency and 4π detection capability. An additional advantage of the proposed detector is the positioning of the photon sensors inside the detector, behind the scintillators. This improves the radiation hardness, a critical requirement for space applications, and ensures better gain stability by minimizing temperature gradients across the detector. The key advantages of the proposed detector include its efficient 4π radiation detection across a wide energy range, the fusion of information from both Compton and photoelectric effects for improved source allocation, and the ability to detect multiple sources simultaneously.