3.1 Basic Principles of Radiation Detection
Radiation detectors are essential instruments that allow us to measure the presence and properties of radiation. Their fundamental function is to convert radiation energy into a measurable signal.
The Detection Process
The process of detecting radiation, regardless of the detector type, generally involves three main stages:
- Interaction with Detector Material: An incident radiation particle or photon enters the detector and interacts with its material, transferring energy to the atoms of the medium.
- Signal Generation: This energy transfer creates a measurable effect, such as ionization (creating electron-ion pairs) or scintillation (producing flashes of light).
- Signal Processing and Output: The generated signal is then amplified and converted into an electrical pulse. These pulses are counted or analyzed to determine the count rate or the energy of the incident radiation.
Key Detector Properties
The performance of a detector is characterized by several key properties:
- Efficiency: The probability that a radiation particle or photon emitted from a source will be detected by the detector.
- Energy Resolution: The ability of a detector to distinguish between radiation events of slightly different energies. A detector with good energy resolution can produce sharp, well-separated peaks in a spectrum.
- Dead Time: The time interval during which a detector is unable to detect a second radiation event after a first one has been registered. This is a critical factor at high count rates.