Abstract: Based on the thin plastic scintillation detector,MC simulation was used to optimize the probe combination structure of directional dose equivalent rate monitor. A directional dose equivalent rate instrument for monitoring weak penetration radiation was developed. In the range of 10 μSv/h to 100 mSv/h, the relative inherent error is less than ±6%. In the beta radiation field of ⁸⁵Kr, the angle response of -60° to 60° is better than that of ±40%. The average energy of beta radiation is in the range of 60 keV to 800 keV,and the energy response varies from -24% to 49%. The coefficient of variation is less than 2%. The experimental results show that the radiation performance of the directional dose equivalent rate instrument meets the requirements of GB/T 4835.1—2012.

Key words: plastic scintillator, Monte Carlo method, relative inherent error, angle dependence of response, energy dependence of response