Radiation is an ionizing radiation which is divided into several types. High doses of radiation are hazardous to health also of human life. Unit sievert is applied to measurement of impact of radiation on an organism. More widespread size of measurement of radiation – heat – means the radiation dose absorbed by substance.
What is radiation?
Invisible and imperceptible radiation can kill the person in few hours or days. This ionizing radiation in a natural look meets on all Earth's surface, but in too small quantities. But there are places where the radiation background is much higher, and at nuclear plant accidents, during nuclear bombing and in other situations the dose of radiation can exceed norm several times.
From the scientific point of view radiation represents a stream of microscopic particles which can ionize the substance which is found on their way. Under such influence in living cells of biological organisms including the person, chemical compounds alien, not peculiar to it are formed. The correct course of intracellular processes stops, structures of cages collapse, gradually they perish.
If a dose small, then cages can independently recover from such damages.
Measurement of radiation
There are several units for measurement of radiation which are used depending on a situation. If the absorbed dose, that is that dose of radiation which is absorbed by a certain unit of mass is measured, then used so-called heat which actually represents the number of joules on kilogram.
This unit is called in honor of one of the most outstanding figures among the scientists who were engaged in radiobiology – Lewis Gray.
But such measurement is not used at the description of impact of radiation on a human body. For this purpose apply other size which measures an effective dose. It is called sievert, this unit is used only since 1979, but already all modern dosimeters defining radiation show results in this unit of measure called in honor of the physicist – Rolf Zivert. The effective dose depends on several parameters: from radiation type (there are alpha, beta also gamma-rays), from orientation of radiation (various human organs differently resist to radiation). In certain conditions the coefficient of biological danger which is multiplied by quantity becomes clear heat, that is the absorbed dose, and receive value in sieverts. Such known unit of measure of radiation as X-ray, belongs only to gamma radiation, or x-ray. One sievert is approximately equal to hundred X-rays. For determination of activity of a radioactive source, that is the number of disintegrations of kernels for a certain period, one more unit – becquerel is applied. Kinetic energy of particles is measured in electronvolts.