What mechanism provides high sensitivity in Gas-Filled detectors?

The mechanism that provides high sensitivity in Gas-Filled detectors is secondary ionization. This process occurs when high-energy radiation, such as gamma rays or X-rays, interacts with the gas molecules within the detector. As these high-energy photons enter the gas, they can ionize the gas molecules, creating free electrons and positive ions.

When these free electrons are collected under the influence of an applied electric field, they can gain sufficient energy to ionize additional gas molecules—this process is known as secondary ionization. This chain reaction significantly amplifies the initial signal, leading to higher sensitivity in the detector. In essence, even a small amount of radiation can result in a large response from the detector due to this secondary process, which effectively enhances the detector's ability to sense and quantify low levels of radiation.

Understanding the role of secondary ionization is crucial, as it directly relates to the ability of Gas-Filled detectors to detect even minimal amounts of ionizing radiation with high efficiency. This mechanism is what makes these detectors particularly effective in a variety of applications, including radiation therapy and diagnostic imaging.