Dosimetry is an applied branch of nuclear physics. He is engaged in the study of ionizing radiation, as well as related moments - penetration power, protection, assessment methods. This is a very important area that deals with security issues when dealing with nuclear elements.
Introductory information
Dosimetry is an activity aimed at studying radiation, their power, the accumulation of results in organisms and objects, as well as the consequences. This topic is very extensive. Of greatest interest is the amount of energy of ionizing radiation that is absorbed by a unit mass of the irradiated medium. The numerical value that allows you to display the scale of the process is called briefly - the dose. Its power is the amount of radiation that occurs per unit of time. The main task that dosimetry is called upon to perform is to determine the value of the amount of ionizing radiation energy interacting with various media and tissues of a living organism. The applied significance of this section of nuclear physics can be characterized in the following points:
- Allows you to conduct a quantitative and qualitative assessment of the biological effect with external and / or internal exposure of the body for various doses of ionizing radiation.
- It makes it possible to form the basis for taking measures to ensure an adequate level of radiation safety in the case of work with radioactive substances.
- It is used to detect a radiation source, determine its type, amount of energy, degree of impact on surrounding objects.
Definition
Dosimetry is a tool for tracking the ability of elementary nuclear particles to make unauthorized transitions between different states or even to other atoms. Indeed, in this case, the emission of particles (electromagnetic waves) is observed. Different types of process produce different results. The generated radiation can vary in its penetrating ability, as well as the specificity of the effect on the human body. Moreover, it should be noted that this is usually implied in a negative direction.
How are the studies conducted?
Dosimetry methods involve the use of specialized equipment. Alas, people do not have any organs that would allow us to talk about the problematic nature of individual places. And if a person begins to guess about something like this by external signs, then, most likely, this knowledge is already late. The equipment used - indicators, dosimeters, radiometers, spectrometers - allows you to get a complete picture of the situation in the framework of the goals. After all, it is always necessary to know what exactly is measured - beta, gamma or neutron radiation. Alpha can be discounted, as it is characterized by low penetration, other species will have time to kill a person even before they are dealt any significant damage.
Norm
If we talk about the recommended indicators, then they make up only 20 micro-roentgen per hour. Although it should be noted that people can live quietly for decades, even where the radiation background is thousands of microR / h! This situation is due to the fact that the human body has good indicators of persistence and output of radionuclides. But if you increase the dose of radiation, the amount of damage increases. Starting from a dose of 100 Rad, a person earns a mild radiation sickness. As it increases, the size of the damage increases. And upon reaching the range of 500-1000 Rad, a person dies quickly. A dose of over one thousand provides instant death.
Value calculation
And what kind of indicators are these? To determine the radioactivity, dosimetry of ionizing radiation uses quite a few non / system units. What does it look like in practice? The quantity of decays of an atomic nucleus per unit time is used to characterize directly radioactivity. Measured in becquerels. 1 Bq equals one decay per second. But in practice, it is more convenient to use an off-system curie unit, which is equal to 37 billion becquerels. They are used to determine the concentration of nuclides in air, soil, water or the volume of a substance. Indicators such as grays are used to calculate the absorbed dose. They show how much energy was absorbed by a particular substance or living organism. A non-systemic analog of this unit is already mentioned above. Roughly speaking, they are correlated in this way: 1 Gy = 100 R. The absorbed dose rate is measured in gray (rad) per second. But this is not all the parameters that you need to know in the calculations. The number of charges (the total electronic value of the ions) that occurred during irradiation in the medium is called the exposure dose. It is expressed in pendants per kilogram. Radiation dosimetry provides for the presence of an off-system unit in this case too. This is the aforementioned x-ray and its multiple traveling (milli and micro). They relate as 1 P = 2.58 x 107 C / kg. And the last is the equivalent dose. This value is used to display the biological effect that occurs when radiation in a living organism. The sievert and its marching units are used as a system unit. The use of rem is also common. 1 Sv = 100 rem. By the way, 100 P is also equal to 1 Sound.
Let’s say a word about protection
The basics of dosimetry will be incomplete without considering protection options. There are a number of basic approaches:
- Shielding. One of the main ways to prevent the irradiation process. Based on the use of effective materials that trap radioactive particles.
- Distance. To move away from the source of radiation is the best way. When choosing a specific distance, it is necessary to focus on the intensity, topography and climatic conditions.
- Time. This is not so much a defense as a reduction in influence and derivative consequences. The less time a person spends around the source, the better his deeds will be.
- Special means. Materials and preparations (water / food / medicine) that can reduce the effect on the body. The second also contribute to the withdrawal of radionuclides.
That, in general terms, is all that a person needs to know.