Which type of radiation is not typically measured by standard radiation detection devices?

Thermal radiation is the correct answer because it refers to the electromagnetic radiation emitted by all objects as a function of their temperature, which primarily exists in the infrared spectrum. Standard radiation detection devices, such as Geiger-Müller counters, scintillation counters, and dosimeters, are specifically designed to measure ionizing radiation—forms such as alpha particles, beta particles, and gamma rays. These types of radiation can ionize atoms and molecules, leading to detectable energy levels that these devices can measure.

In contrast, thermal radiation does not have the same ionizing properties and falls outside the range of energy typically detected by standard instruments meant for radiation monitoring. While thermal radiation may be measured in other contexts (like temperature measurements using infrared sensors), it is not within the scope of what standard radiation detection devices are intended to measure for safety or regulatory purposes.