Al3+ Codoped LiF-CaF2:Eu2+ Bright Eutectic Scintillators for Large-Area Thermal Neutron Detectors

Eutectic scintillators with 6Li-containing thermal neutron absorbers are capable of efficient thermal neutron detection due to lamellar or rod-like optical waveguide structures formed by directional solidification. However, developing stable and bright eutectic scintillators with excellent neutron imaging capability remains a challenge. Here, the performance parameters for the scintillator have been substantially improved by the Al3+ codoping strategy in the LiF-CaF2:Eu2+ system. Due to the Al3+ codoping, the photoluminescence quantum yield (PLQY) is enhanced from 55% to 80%, the light yield is increased from 11,000 to 16,000 photons/thermal neutron, and the scintillation decay time is shortened by about 30 ns. It was shown that Al3+ codoping can effectively reduce the low-frequency shallow-energy level traps. Furthermore, large-sized (50 × 50 × 1.5 mm) translucent LiF-CaF2:Eu2+, Al3+ eutectic ceramics have been fabricated for an Anger-logic position-sensitive detector to realize two-dimensional (2D) thermal neutron detection. A codoped LiF-CaF2 eutectic scintillator provides a ∼1 mm spatial resolution and thermal neutron detection efficiency 16% higher than that of a commercial GS20 scintillator. This research paves the way for the application of large-area eutectic scintillators for efficient thermal neutron detection.