How to choose a good radiation background dosimeter

An essential component in any home, a dosimeter serves as a vital tool for monitoring radiation levels. The term "dosimeter" encompasses a wide range of equipment designed to measure radiation. Each model and its variations can differ in terms of how they operate, their construction, functionality, and design. When selecting the ideal dosimeter, it’s crucial to prioritize the user’s specific needs. Whether it’s a dosimeter, radiometer, or a combination of both, the intended purpose will ultimately determine the most suitable model.

Professional or household

Each dosimeter has the primary purpose of ensuring human safety, thus it is crucial to determine its equipment class. It is essential to comprehend the distinction between household and professional models. Dosimeters or radiometers of professional grade are utilized by specialists operating in potentially hazardous conditions, such as nuclear power plants, weapons or medical equipment factories, or banks. To safeguard their employees’ health, many organizations acquire radioactive background meters. These devices are subjected to strict production controls, and their minimum requirements are governed by law.

Every specific model is listed in the Rosstandart register. If a device is not included in the register, despite its parameters or the assurances provided by the seller or manufacturer, it cannot be considered professional.

In most cases, professional radiometers or dosimeters far surpass household-level instruments in terms of capabilities. They have the ability to detect even the slightest increase in radioactive radiation and can detect high doses from a distance. Additionally, professional devices are significantly more accurate, with an average model having an error rate of less than 15% and reliable declared parameters. The operating principle of a household-class dosimeter or radiometer is often similar to that of professional versions. The main differences lie in their relatively affordable cost, compact size, and user-friendly design. Not every model can distinguish between beta and gamma radiation, and there are very few meters that can measure alpha particles. However, the need for this level of specificity is rare. While the error and accuracy of data recording is naturally lower in household devices, it is still sufficient for determining and measuring levels of radioactivity.

Types of counters

1. Mica Geiger counters (end meters) are capable of detecting alpha and beta radiation.
2. The popular gas-discharge SBM-20 and its variations are commonly used for measuring radiation. The smaller versions SBM-10 are suitable for compact devices, but it is important to note that they can only detect significant exceedances of the normal level. These sensors are capable of detecting beta and gamma radiation.
3. Thermoluminescent lamps, also known as TLDs, are known for their small size and are most commonly used in individual dosimeters. They are particularly effective for measuring accumulated dose from X-rays.
4. Manufacturers claim that scintillation crystals are more sensitive than any other crystals (about 20 times more sensitive than Geiger counters) and can be installed even in pocket-sized models. Additionally, they are more compact. However, it should be noted that these crystals, when wrapped in foil, are incapable of detecting alpha radiation. These crystals are frequently used in radiometers to locate sources of radiation.

Scintillation elements utilizing CdWO4 crystals

The dosimeter can incorporate any of the aforementioned detectors, with the specific choice of counter always influencing the price and the range of applications for the device.

Overview and classification

To put it simply, devices for measuring radiation in households are commonly referred to as "dosimeters," but this term is not entirely accurate. While it may be suitable for combined models, radiometers serve a different purpose altogether.

One major distinction between the two meters lies in the ability of a dosimeter to record the dose and rate of radioactive radiation over a specific time period, such as a minute or a day. On the other hand, radiometers are designed to measure the current radiation rate (flux density of radioactive particles) of a particular source or various samples. In simpler terms, a radiometer is used to identify the source of radiation or determine the level of contamination in real-time, while a dosimeter measures the accumulated dose. There are numerous types of dosimeters available, and when selecting a suitable one, it is advisable to consider devices that combine both functionalities.

Personal dosimeters

Usually referred to as a "personal dosimeter" or "signaling device," this compact device is typically smaller than a regular keychain. It alerts the user to the detection of ionizing radiation through an audible or vibrating signal. Some models with thermoluminescent meters also include a light signal, which adds to its convenience.

MT2033 Geiger Key Fob Dosimeter

The MT2033 Geiger Key Fob Dosimeter is a compact and user-friendly device used for measuring radiation levels. Unlike other dosimeters, it does not have a display or a wide range of options. It is designed to be easily worn on the belt or kept in a pocket. When entering a dangerous zone, the dosimeter emits a signal to alert the user, and all recorded data is stored in its memory.

Depending on the specific model, the MT2033 Geiger Key Fob Dosimeter can measure various types of radiation, including neutron, photon, beta, or gamma radiation.

Although the technical parameters of the alarms are relatively low, the dosimeter provides comprehensive information about radiation levels when connected to a PC or smartphone.

Personal dosimeters are employed to ensure the safety of individuals when they are in close proximity to a potentially dangerous zone, excluding any research-related intentions. However, certain contemporary variations have the capacity to serve both purposes. An example of this is a keychain dosimeter that can be affixed to one’s garments, providing prompt notification of any potential hazards and monitoring the increase in levels of ionic radiation, as well as accurately measuring the cumulative dose absorbed by the skin.

Pocket versions

The classic household dosimeter has gained popularity among the general public due to its convenience and compactness, leading to the prevalence of pocket models. There are numerous variations of these devices, all of which share a number of key features:

• Compact size – designed to easily fit into a standard pocket
• Battery or regular battery power supply
• Detection and measurement of beta/gamma radiation
• Inclusion of an easily readable display
• Straightforward and user-friendly interface

A revolutionary portable device, Atom Fast, has been introduced to the market!

These devices have a limited scope of application, primarily focused on measuring the natural radiation background. With the help of a dosimeter, it is possible to detect any excessive dose and record the relevant readings. This compact device is also capable of diagnosing various building materials and products; however, it is important to note that it will only be able to detect high levels of activity.

For those seeking more advanced features, there are sophisticated models available, including the cutting-edge Atom Fast scintillation pocket dosimeter. This compact dosimeter, while lacking a display, offers a diverse range of functions. By synchronizing it with your smartphone or tablet, you can easily set threshold values, generate detailed graphs, and even visualize the collected data on a map.

Portable dosimeters

Portable devices are similar to pocket versions in many ways, with the main difference being their slightly larger size. However, internally they are the same as radiometers or dosimeter-radiometers, equipped with a small display and a range of options:

• Logging of gamma radiation;
• In rare cases, measurement of beta particle flux density;
• Data storage;
• Synchronization with computers or other devices for output and analysis of the collected data;
• Various types of signals: light, sound, vibration, or display.

Most often, a portable radiation dosimeter combines a dosimeter and a radiometer, making it a compact version of a device used to detect sources of radiation.

Having a large size enables the installation of up to four detectors within a single case, thereby enhancing accuracy and area coverage during scanning activities while also reducing the time required for measuring radioactive background levels. The handheld device does not necessitate the use of any specialized equipment for data retrieval, as a PC, tablet, or smartphone will suffice.

There is a wide variety of dosimeter-radiometers available, suitable for both household and professional use. Among the latest innovations is the SOEX Quantum, which can be considered a perfect compromise. It is a compact and functional dosimeter equipped with two SBM-20-1 counters and a color display. This device is included in the register of Rosstandart, indicating its compliance with standards. However, despite the manufacturer’s claims, the SOEX Quantum cannot differentiate between beta and gamma radiation. Nonetheless, it is effective in detecting high levels of radioactivity in products, building materials, and other objects.

Tips for choosing

Prior to choosing a dosimeter, it is important to determine the specific purpose for which it will be utilized. Any of the aforementioned models will be capable of detecting increased levels of radiation. If this is the sole purpose, the selection of a dosimeter can be solely based on cost.

There is another classification of devices based on their mode of operation. It is beneficial to familiarize oneself with which dosimeter will be suitable for the given task before making a purchase.

1. Thresholdless indicators with low sensitivity – this type of dosimeter can detect the presence of radioactive background from any object, but nothing more.
2. Signalizers are similar indicators, but with predetermined threshold values, which the dosimeter notifies of through an audible or vibration signal (such as Neiva-IR-001).
3. Meters are equipped with highly sensitive and precise radiation sensors that offer users detailed information regarding the detected radiation variations. These dosimeters are ideal for measuring the radioactivity levels of various objects. For instance, the MKS-03SA model can be employed to analyze construction materials or jewelry.
4. Detectors, on the other hand, are utilized for locating radiation sources. Although they are not as accurate as meters, they possess a remarkable sensitivity to any alterations in background radiation levels. Typically, these instruments employ scintillation crystals as detectors. In simple terms, they are capable of detecting radiation from a distance, and by observing the fluctuations, one can identify the direction to the source. Scintillation dosimeters primarily respond to gamma rays, and occasionally to "high beta" as well.
5. Spectrometers are more advanced equipment as they can identify the specific isotope responsible for the rise in radiation levels, in addition to detecting radiation sources. These devices are 10 times more costly compared to household dosimeters, like the LD-07 laser dosimeter.

Having two or more counters is beneficial for dosimeters as it allows for quicker detection. SBM-20, SBT-11, SBT-9, and Beta are examples of highly sensitive sensors that have established themselves in this regard.

Take note of the recommended upper threshold of measurements which is 10,000 µR/h. It is imperative to use devices with an appropriate upper value as lower value devices may not be able to detect high levels of radiation accurately. In such cases, the indicator may either not register it at all or underestimate the actual values, posing a significant risk to human safety.

In the event that you have to choose between the SBM-20 and end mica sensor, it is advisable to opt for the latter. This is because they are not only more sensitive but also capable of detecting "soft beta radiation". The only downside is that they are fragile and must be handled with care, keeping them away from sudden changes in pressure, shocks, vibrations, vapors from liquids, or any contact with mica.

It is uncommon to require the use of scintillator "finders" in household settings. If there happens to be a need for one, it is important to consider the size of the scintillation crystal: the larger the crystal, the more sensitive the device will be.

It is advisable to avoid purchasing decommissioned military dosimeters and instead opt for modern models. In the best-case scenario, the device will not function properly, but in the worst-case scenario, it could be hazardous. Some variations featuring pin-diodes or smartphone applications may have some validity to being called "dosimeters," but in practice, they prove to be useless.

Operation of meters

To ensure the proper functioning of the dosimeter or to test its performance, it is rather straightforward – just observe the readings displayed by the device.

The background radiation levels can range from 5 to 15 µR/hour, while granite emits about 35 to 90 µR/hour, and "potassium chloride" fertilizer typically registers from 20 to 40 µR/hour.

Detailed instructions on how to operate a dosimeter or radiometer can be found in the user manual. Generally, household-grade devices are user-friendly with an intuitive interface.