What is measured by the radiation and the radioactive radiation
Units of radiation, its types
Radiation exposure is of several types, which leads to the degree of damage. To understand what is measured by the radiation, consider what radiating waves exist, and their influence on living tissue.
The types of radiation waves
The background radiation that exists on earth is natural or artificial (anthropogenic sources). Man is constantly in the field of radiation.
Alpha radiation occurs in the decay of heavy chemical elements in atoms (uranium, thorium, radium). The way in which they can hit, short: the air is not more than 8 cm in body biological fluids of 0.01-0.05 mm. Particle cannot penetrate a sheet of plain paper or the dead cells of the skin. But there is one potential danger. There are chemical substances that are able to release alpha particles. If they get into the human body through the blood stream will spread and settle in the internal organs (often in the endocrine glands and lymph nodes). This will cause irradiation of the body from the inside.
Beta radiation – a stream of electrons in the decay of the nuclei of certain substances. In the human body, they penetrate to a distance of 15 cm Is due to their microscopic size. Such waves are used in medicine for radiation therapy for cancer.
Neutron radiation – the flow of micro-particles that have no electric charge. It is characterized by the greatest force of penetration. It is used as a particle accelerator in research and industry, for laboratory research.
Gamma radiation has high penetrating ability. Has no charged particles, therefore is not subject to the influence of magnetic or electric fields. Scope of application:
- medicine, radiation therapy;
- food processing, preserving;
- the space industry;
At high doses of exposure causes acute radiation sickness, long-term effects on the body – chronic.
Units that measure radiation
In physics there is the term «radiation dose». It reflects the impact of the measure on a living organism to ionizing radiation (light and UV). Mistakenly to radiation include infrared radiation and radio waves, they do not have sufficient energy to ionize the atoms.
Measurement of radiation depending on the kinds of doses:
- The exposure dose. This is a measurement of the amount of x-ray radiation in the air. It reliably measured under these conditions: atmospheric pressure 760 mm Hg. art., t = 0°, no humidity. This value displays the ratio of: the sum of all positive or negative ions in the air to the total mass of air within a certain volume. Based on the SI system of units, adopted this unit of measure C/kg (Coulomb/kg). A common unit of measurement is roentgen, 1R = 3876 Cells/kg.
- Absorbed dose. It denotes the amount of radiation (radioactivity), which consumed the body or any substance. The radiation effect depends on the amount of energy, which led to chemical and physical changes. The ratio of absorbed radiation to the mass of the substance, which he swallowed. In the SI system there is a unit of measure – 1 Gy (gray) = the mass of 1 kg is an energy equal to 1 Joule. Another unit is rad (1 Gy = 100 rad).
- Equivalent or biological dose. Different types of radiation, given equal absorbed dose is not the same effect on living tissue. This is due to the fact that molecular particles produce different number of ions. The higher density of ionization, the more breaks a living substance. Biological radiation is measured in the unit SV (sievert). It displays the ratio: 1 SV of equivalent dose, which is absorbed by 1 kg of living substance with the subsequent biological effect. Another name for the unit of REM (1 SV = 100 REM).
- Effective dose. It shows the probability of consequences of radiation exposure for both the whole body and for individual tissues and organs. Sensitivity of living matter is different, so the dosage of irradiation is calculated taking into account the coefficient of radiation risk. Effective dose is the sum of ionization of the whole body multiplied by the coefficient. The smallest ratio of the skin and surface of bone, the largest – in the lungs, intestines, stomach.
Any radiation, including gamma radiation, is measured by a special instrument. With it, monitor regulatory indicators.
The measure of radiation is measured in such cases:
- monitoring of air, land and water around nuclear power plants;
- before the construction of residential areas;
- when you explore geological, archaeological expeditions in unknown areas.
Safe radiation background in which the person does not receive radiation equal to 10 mSv/h, the maximum permissible dose of 50 mSv/h.