Abstract: To investigate the differences in detection performance and the underlying influence mechanisms of various types of α/β surface contamination monitors for low-energy beta rays, this paper selects a ¹⁴C planar source (with a maximum beta energy of 156 keV) as a typical research subject and systematically conducts an experimental study on surface emission response characteristics using multiple commercial monitors equipped with scintillation detectors, Geiger-Müller (G-M) counters, and proportional counters. The results indicate that different instrument types exhibit varying responses to low-energy beta rays from ¹⁴C. Specifically, the scintillation detectors show a wide response range from 0.2% to 21.1%, the G-M counters show a response range of 8.3% to 12.2%, and the proportional counter yields a response of 7.9%. However, for windows made of the same material, the mass thickness is negatively correlated with the instrument′s response to ¹⁴C beta rays, while the penetration rate, which is determined by the mass thickness, is positively correlated with the response value. These findings can provide important technical references for the surface contamination monitoring of ¹⁴C, and also hold practical value for the domestic development of surface contamination monitors, performance optimization, and user equipment selection.

Key words: low-energy β, ¹⁴C, surface emission rate response, surface contamination measurement, detection window, penetration rate