Radiation Detection Systems: A Basic Understanding of Their Types

Radiation detection

Knowing the precise levels of radiation in the immediate surroundings is important, especially if you work with or around it. This task is achieved with the help of radiation detection systems of different types.

A brief idea of these variants and their applications can go a long way to not only help one find the ideal detection system for the specific task but also to maximize the utility of the chosen instrument.

Types of Radiation Detection Systems at a Glance

There are three major types of radiation detection systems based on the particular requirement. These have been briefly explained below:

Gas Filled Radiation Detection Systems

Gas-filled detectors are some of the most commonly used ones, with variants that work differently using similar principles. The gas present in these detectors undergoes a reaction when it comes into contact with radiation. Once it becomes ionized, the electric charge is measured.

The variants mentioned above include:

  • Ionization chambers
  • Proportional counters
  • Geiger-Mueller (G-M) tubes

The intensity of the applied voltage across the detector makes the difference between these three types of gas-filled detectors.

1. Ionization Chambers
These are low-voltage detection systems in which only the primary ions are recognized. These ions are created when a radioactive photon reacts with the gas. Therefore, the values of the readings are directly proportional to the number of ion pairs. These prove useful in the quantification of high-energy gamma rays. This is because they are devoid of dead time-related problems typically faced by other environmental monitoring solutions.

2. Proportional
Their design is such that the mechanism remains similar to that of an ionization chamber for most of the chamber space. However, these contain a stronger voltage for the ions to move closer to the detector anode. The drifting ions lead to an increase in the voltage until the stage of the gas amplification effect.

3. Geiger-Mueller Tube
This is also an important type of gas-chamber radiation monitoring systems. It is also where the name “Geiger Counter” originated from. Many people mistakenly refer to all global radiation detection solutions as “Geiger Counters” in general due to the subversion of popular culture, whereas it only refers to a highly specific type of detector.

It operates at a significantly greater voltage than the two aforementioned variants and is somewhat different from them too. Since they signal the presence of radiation through a gas-amplification effect throughout the detector anode – irrespective of the scale of interaction – they are mainly useful as simple counting devices.
They can also give the dose rates if the appropriate algorithms are applied.

This is the second category of detectors used in radiation monitoring systems. As the name suggests, these give out light upon detecting the presence of radiation. A scintillator material is used that gives off a distinct light signaling its interaction with radiation photons.
This gives them the ability to catch particular spectroscopic profiles for the radioactive materials that are being measured.

Solid-State Radiation Detection Systems
This is the third major category of detectors that utilizes a semiconductor substance such as silicon that works quite similarly to an ion chamber. However, the difference here lies in the scale of operation – solid-state radiation detection systems work at a substantially lower voltage and a very small scale.

A semiconductor is called so due to its partial resistance to electric current. That’s because although they are highly resistant, they are not as resistant as insulators. This is due to the presence of charge carriers in the lattice of atoms that make up a semiconductor molecule. These charge carriers are either electrons that are ready to attach to suitable atoms or electron holes – voids where electrons should be.