The working principle of gamma ray detection technology mainly involves the interaction between gamma rays and matter, as well as the response of detection equipment to these interactions. The following is a detailed explanation of the working principle of gamma ray detection technology:

1、 The interaction between gamma rays and matter

Main effects:
Photoelectric effect: Gamma rays interact with atoms in matter, causing an inner electron in the atom to gain sufficient energy and escape, forming photoelectrons.
Compton effect: Gamma rays undergo inelastic collisions with free or bound electrons in matter, resulting in a decrease in gamma ray energy and scattering, while electrons gain energy and fly out.
Electron pair effect: At high energy, gamma rays can interact with the Coulomb field near the atomic nucleus, converting into a positive electron and a negative electron (i.e. electron pair).
Secondary effects:
The secondary electrons generated by these interactions can cause ionization and excitation of atoms in matter. Ionization is the inelastic collision between charged particles and bound electrons of matter atoms, causing bound electrons to gain energy and become free electrons, forming ion pairs.
Excitation refers to the secondary electrons causing the bound electrons within the atom to transition to higher energy levels, and the stimulated atom emits photons and produces fluorescence during the de excitation process.

2、 Working principle of detection equipment

Detector type:
Gas detector: Early use, low sensitivity, limited applicability, now replaced by more advanced technology.
Scintillator detectors, such as NaI (Tl) detectors, use scintillation crystals to convert the energy of gamma rays into visible light signals, which are then amplified and processed by photomultiplier tubes (PMTs). This detector has high detection efficiency, but its energy resolution performance is poor and its volume is large.
Semiconductor detectors have developed rapidly in recent years and are widely used in the fields of nuclear physics, nuclear medicine, and gamma ray astronomy. Semiconductor detectors can directly detect gamma rays and generate electrical signals, with high energy resolution and sensitivity.
Detection process:
After gamma rays enter the detector, they interact with the substances inside the detector.
Generate secondary electrons or photons based on the type of interaction (photoelectric effect, Compton effect, electron pair effect, etc.).
These secondary particles further cause ionization and excitation of the material inside the detector.
The detector amplifies and processes signals generated by ionization and excitation, such as optical or electrical signals.
The processed signal is converted into measurable physical quantities (such as voltage, current, etc.), reflecting information such as gamma ray dose and energy spectrum.



The working principle of gamma ray detection technology is based on the interaction between gamma rays and matter, as well as the response of detection equipment to these interactions. By selecting the appropriate detector type and optimizing the detection process, effective detection and accurate measurement of gamma rays can be achieved. With the continuous development of technology, gamma ray detection technology will be applied and developed in more fields.