Monte Carlo estimation of neutron absorbed dose in pure and rare earth-doped hydroxyapatite

Ionizing radiation exhibits unique characteristics that necessitate accurate detection and quantification to ensure proper control and utilization. Among various measurement techniques, thermoluminescent dosimetry (TLD) is noteworthy for using semiconductor materials to determine the amount of absorbed radiation. Identifying costeffective and sustainable materials, either natural or synthetic, for dosimetry purposes remains a key research interest. Hydroxyapatite (HAp), a calcium phosphate-based biomaterial, has emerged as a promising candidate for detecting different types of ionizing radiation. Recent advances in computational modeling allow for predicting material responses to specific radiation fields. In this study, the Monte Carlo method, implemented via the MCNP6 code, was employed to estimate the absorbed neutron dose in pure HAp and HAp doped with dysprosium (Dy) and europium (Eu) at 0.1 and 0.5 M concentrations (0.23 and 1.12 wt%, respectively). For monoenergetic neutrons, the absorbed dose in pure HAp and Dy-doped HAp (0.23 and 1.12 wt%) was similar and lower compared to Eu-doped HAp. Notably, Eu-doped HAp at1.12 wt% exhibited the highest absorbed dose at lower energies. Above approximately 1E(-1) MeV, the absorbed dose responses of all materials converged. For poly- energetic neutrons, HAp:Eu at 1.12 wt% also presented the highest absorbed dose at an average energy of 1 MeV, while at energies above 5 MeV all materials displayed a similar response.