What is the mechanism by which Alpha radiation is detected in CRMs?

Alpha radiation is detected in Continuous Radon Monitors (CRMs) primarily through a mechanism where ionization occurs when alpha particles collide with air molecules. When an alpha particle enters the detector, it interacts with the surrounding air, ions, and electrons, resulting in ionization. This ionization creates charged particles, which contribute to an electrical pulse that the monitor can detect and quantify.

The reason the detection method is characterized by electrical pulses is that these produced charges can be collected and translated into a readable signal. In the context of CRMs, the detection system utilizes this principle to assess the concentration of radon by measuring the intensity and frequency of the pulses generated by the detection of alpha particles.

In contrast, while photographic film exposure does capture ionizing radiation, it does not actively yield immediate feedback on the radiation levels, making it less practical for continuous monitoring. Thermal emission is more relevant to different types of radiation detection, while ionization of the surrounding air, although part of the process, specifically relates to generating those electrical pulses, which is why "electrical pulses from detected particles" captures the essence of the detection mechanism in CRMs effectively.