Determination of the response to the atmospheric cosmic radiation of a neutron dosimeter assisted by Monte Carlo simulation

A TLD-based dosimeter of polyethylene-lead-polyethylene, was developed and characterized with Monte Carlo simulations, using the MCNPX code. This passive system for the determination of the ambient dose equivalent (H*(10)) for neutrons over a wide energy range can be used for the dosimetry of neutrons from atmospheric cosmic radiation, on the ground, and onboard aircraft. A method assisted by Monte Carlo simulations that improves the calibration of fast neutron dosimeters based on moderation and thermalization of the incident fast flux and the measurement of the thermal flux by a sensor, which respond mainly to thermal neutrons, is presented in this work. The H*(10) energy response of this dosimeter was obtained from simulations for monoenergetic neutrons from 10^-10 to 10⁴ MeV. The validation of the modeling was done with irradiations for ISO standard neutron fields of ²⁴¹Am-Be, ²⁵²Cf and ²⁵²Cf(D₂O) at Instituto de Radioprotecao e Dosimetria (IRD, Brazil) and at CERN-EU high-energy reference field (CERF). (authors)