What is the primary disadvantage of a film badge in a mixed radiation field?

A film badge is primarily designed to measure radiation exposure by utilizing the film's response to ionizing radiation. In a mixed radiation field, which includes different types of radiation such as alpha particles, beta particles, and gamma rays, the film badge does not have the capability to differentiate between these types effectively. This inability to distinguish between various radiation types limits its usefulness in environments where the nature of radiation is critical for appropriate safety measures or therapeutic decisions.

For instance, if a half-value layer of a certain material is required to assess the exposure accurately, a film badge might not provide the necessary information regarding whether the exposure was from alpha, beta, or gamma radiation. This characteristic can lead to potential misinterpretation of exposure levels and inadequate protection measures for individuals working in such fields.

While this particular device has other operational characteristics, such as potential for malfunction, reusability, or the need for calibration, these factors do not directly relate to the main disadvantage presented by the inability to distinguish types of radiation in mixed fields. Thus, the inability to identify different radiation types is a critical limitation of film badges in specific environments.