Photoluminescence characteristics of NaCl: Cu sintered dose tablets under X/γ irradiation
Authors: Li Zhe-Xu , Li Xin-Huan , He San-Jun , Zhou Zhi-Qian , Liu Li-Yan , Yu Wan-Tang , Zhao Xiu-Liang ,   School of Nuclear Science and Technology, University of South China, Hengyang 421001, China,   School of Civil and Traffic Engineering, Qinghai Minzu University, Xi’ning 810007, China,   Department of Oncology, Yichang First People’s Hospital, Yichang 443099, China
Published: March 2022

In this paper, NaCl: Cu circular dose tablets with a size of 5×1.8mm are prepared by sintering pure NaCl and CuCl powder as raw materials. They are placed in a four-element shell and sealed with plastic film to overcome the moisture absorption of the material. Their photoluminescence characteristics are studied by using an Inlight 200 automatic photoluminescence measurement system. The results show that the X-ray characteristic peaks of NaCl: Cu sintered at 650 ℃ and 400 ℃ appear at 27°, 32°, 45°, 56°, 66°, 75° and 84° respectively. Compared with the data given by XRD standard card of pure NaCl crystal (pdf-#88-2300), those peaks of the sample sintered at 650 ℃ are more consistent with the data given by the standard card. In the scanning electron microscope image, it can be seen that the grains are wholly welded and closely connected, and the characteristic grains in the sintering process have good welding effect. After Cu<sup>+</sup> ion doping, the lattice structure of NaCl is slightly deformed. After high-temperature sintering, the mass transfer of Cu<sup>+</sup> ions occurs at an atomic level in NaCl, and the particles are combined into a coherent solid structure. For X/γ-rays, the photoluminescence response of NaCl:Cu dose sheet to low-energy rays is higher than that of the same kind of rays with high energy. When using NaCl:Cu dose sheet to calculate the cumulative photoluminescence dose, it is necessary to consider the ray category and ray energy of the radiation source at the radiation site. The photoluminescence curve of NaCl:Cu dose sheet has typical exponential attenuation characteristics. The deflection angle of dose sheet has influence on the measured value: the greatest influence extent is 13.5%. With the increase of deflection angle of dose sheet, the area irradiated by γ-ray decreases, and the response of internal lattices to γ-ray decreases slightly. The uniformity of NaCl: Cu raw material particle sizes has a great influence on the distribution consistency of photoluminescence response of dose tablets. The decrease of sample particle size during tablet pressing can improve the contact surface area between NaCl and CuCl. The increase of contact surface area can improve the diffusion and transfer efficiency of Cu<sup>+</sup> ions, increase the number of dose traps in the crystal, and make the overall count higher. When the particle sizes are more uniform, the Cu<sup>+</sup> ion transferefficiencies and quantities of different dose tablets are close, the difference in the number of dose traps is reduced, and the photoluminescence sensitivities are closer. The coefficient of variation of the repeatability test experiment is 2.28%. The consistency of the repeated measurement data is good. The lattice structure and lattice defects of the material are not changed in the process of photoluminescence measurement and photoannealing. In a dose range of 1-1000mgy, with the increase of irradiation dose, the photoluminescence response of NaCl: Cu and NaCl dose tablets gradually increase and show a good linear relationship. The photoluminescence response of NaCl: Cu is 2-to-4 times higher than that of NaCl dose tablets. The NaCl: Cu dose tablets prepared by the sintering method can be used as dosimeters for monitoring personal or environmental dose.