Fig. 3

The investigation on the excitation mechanism. a the overlayed images of the optical signal generated by Gd₂O₃:Eu-100. b the optical signal intensity of each tube. c–f the images of the optical signal generated by Gd₂O₃:Eu-100 through interaction with CL, with β particles and γ radiation blocked by the lead plate and CL reflected by the mirrors (c), by Gd₂O₃:Eu-100 through interaction with CL, β particles, and γ radiation (d), by Eu₂O₃ through interaction with CL (e) and by Eu₂O₃ through interaction with CL, β particles, and γ radiation (f). g, h the optical signal intensity of each condition for Gd₂O₃:Eu-100 (g) and Eu₂O₃ (h)