PRINCIPLES OF OPERATION AND THE EQUIPMENT FOR OBSERVATION, REGISTRATION AND RADIATION MONITORING OF RADIOACTIVE EMANATIONS AND PARTICLES

Almost all methods of observations and registrations of radioactive emanations and particles are built on their ability to make ionization and excitation of atoms of the medium. Charged particles evoke these processes directly, quantums and neutrons are found because of ionization, that evokes with the help of fast charged particles that appear as the result of their interaction with electrons and atomic nuclei of the medium. Secondary effect, that follow these processes, such as alternating light, electric current, darkening of the photographic plate, allow to registrate the flying particles, to count them, to differ them one from another, and measure their energy. The instruments, used for registration of radioactive emanations and particles can be divided into two groups:
1) the instruments that allow to registrate the passing of the particle through some region of space and in, some cases, to find its characteristics energy, for example (scintillation counter, Cerenkov counter, impact ionization chamber, gas-discharge counter, semi-conducting counter);
2) the instruments, that allow to observe, for example, to make photoes, traces of the particles in the chemical agent(Wilson (cloud) chamber, diffusion (cloud) chamber, bubble chamber, nuclear emulsions).

Scintillation counter. The observation of scintillations - alternating light after the hit of the fast particles on a fluorescent screen is the first method that allowed U. Crucks and E. Rutherford at an early age of the nuclear physics (1903) to registrate particles by sight. Scintillation counter is the detector of the nuclear particles, the main elements of that are scintillator (phosphor material) and photoelectric multiplier that allows to transform faint alternating light to electric impulses. Scintillation counters have a high permission in time.

Cerenkov counter. The main function of Cerenkov counters is energy measuring of particles, that move in the chemical agent with a speed that is higher than phase velocity of light in the medium and the weight separation of these particles. We can find the speed of the particle if we know the angle of release of radiation, this means that if we know the mass of the particle we can find its energy. From the other hand, if we don't know the mass, we can find it with the help of independent measuring of the particle's energy. Cerenkov counters are put on the spaceships to study cosmic radiation.

Impact ionization chamber is a detector of the particles. The ionization chamber is an electrical condenser, filled with gas; to its electrodes applies continued stress. Registrated particle comes to the space between electrodes and ionizes gas. Ionization chambers can be of two kinds: integrating (there summed ionized current is measured) and impacted (there passing of a single particle and its energy is measured).

Gas-discharge counter.There are two kinds of gas-discharge counters: proportional (gas discharge in them isn't independent, it extinguishes after the stop of the action of outside ionizer) and GM-counters (gas-discharge in them is indpendent, it keeps up even after the stop of the action of outside ionizer). The particle in the proportional counters isn't only registrated, its energy is measured also. GM-counters registrate the particle without measuring its energy. For registrating the energy of the separate impulse, originated discharge should be extinguished.

Semi-conducting counter is a detector of particles, the mail element of what is crystal detector. Semi-conducting counters are very effective, they can work in the magnetic fields. But the little thickness of the workspace of semi-conducting counters doesn't allow to use them for measuring of the high-energy particles.

Wilson (cloud) chamber (1912) is the oldest and (up to 50-60-s) the only kind of the tracking detector. The Soviet scientist D. V. Scobelcyn (1892-1988) has enlarged the abilities of Wilson chamber; he had put it into a strong electromagnetic field (1927). We can find out the type of the charge of a particle, its energy and mass. The lack of Wilson chamber is its short working time and laboriousness of the result processing.

Diffusion (cloud) chamber (1936) is a sort of Wilson chamber.

Bubble chamber (1952 american physician D. Glazer (1926)). In the bubble chamber the labour substance is superheated liquid. The bubble chamber works cyclically. The size of bubble chamber is like Wilson chamber, but their effective volume is much more bigger, because liquid is thicker than gas. This allows to use bubble chambers for examining long chains of birth and decay of the high-energy particles.

Nuclear emulsions (1927 The Soviet physician L.V. Mysovsky (1888-1939)) is a simple tracking detector of the charged particles. Photoemulsions are used for examining the reactions that are evoken by the particles accelerators of superhigh energies and in cosmic rays.

Spark chambers are a set of a large quantity of a small counters. That's why its information comes out immediately, without the further processing, and at the same time has the characteristics of a track detector.

THE INSTRUMENTS OF THE RADIATION RECONNAISSANCE The instruments of the radiation reconnaissance (radiac instruments) are used to measure the capability of ionizing radiation on the radioactive contaminated area and the extent of contamination of different subjects.

The main instruments of the radiation reconnaissance are DP-5A, DP-5B and DP-5V. The instrument range of DP-5A is divided into 6 subranges.

Subrange The position of the handhold of the switching unit Scale The unit The range

I Õ200 0-200 Ð/÷ 5-200

II Õ1000 0-5 milliroentgen/hour 500-5000

III Õ100 0-5 milliroentgen/hour 50-500

IV Õ10 0-5 milliroentgen/hour 5-50

V Õ1 0-5 milliroentgen/hour 0,5-5

VI Õ0.1 0-5 milliroentgen/hour 0,05-0,5

The main parts of the instrument are: test set and tester, connected with the test set with the help of a flexible cable. On the panel of the test set are: micorammeter, the switch of the subranges, the handle of the high-precision variable resistor, the button of chop of the registrations, toggle switch of the illumination of the scales, the slot of the switching on the telephones.
1-casing; 2- panel; 3 - the button of chop of the registrations of micorammeter; 4- the slot of the switching on the telephones; 5 - handle of the high-precision variable resistor; 6 - micorammeter; 7 - toggle switch of the illumination of the scales; 8 - the switch of the subranges; 9 - releasable connection for the link-up of the flexible cable of the tester; 10 - the bean of the adjuster of mechanical zeroing.

The tester is hermetic.
The tester with took-off body. 1 - iron body; 2 - turning screen; 3 - window; 4 - supporting jut; 5 - gas-discharge counter SI-ÇBG; 6 - gas-discharge counter STS-5; 7 - fee; 8 - captive nut; 9 - handle

Scintillation counter. The observation of scintillations - alternating light after the hit of the fast particles on a fluorescent screen is the first method that allowed U. Crucks and E. Rutherford at an early age of the nuclear physics (1903) to registrate particles by sight. Scintillation counter is the detector of the nuclear particles, the main elements of that are scintillator (phosphor material) and photoelectric multiplier that allows to transform faint alternating light to electric impulses. Scintillation counters have a high permission in time.
Cerenkov counter. The main function of Cerenkov counters is energy measuring of particles, that move in the chemical agent with a speed that is higher than phase velocity of light in the medium and the weight separation of these particles. We can find the speed of the particle if we know the angle of release of radiation, this means that if we know the mass of the particle we can find its energy. From the other hand, if we don't know the mass, we can find it with the help of independent measuring of the particle's energy. Cerenkov counters are put on the spaceships to study cosmic radiation.
Impact ionization chamber is a detector of the particles. The ionization chamber is an electrical condenser, filled with gas; to its electrodes applies continued stress. Registrated particle comes to the space between electrodes and ionizes gas. Ionization chambers can be of two kinds: integrating (there summed ionized current is measured) and impacted (there passing of a single particle and its energy is measured).
Gas-discharge counter.There are two kinds of gas-discharge counters: proportional (gas discharge in them isn't independent, it extinguishes after the stop of the action of outside ionizer) and GM-counters (gas-discharge in them is indpendent, it keeps up even after the stop of the action of outside ionizer). The particle in the proportional counters isn't only registrated, its energy is measured also. GM-counters registrate the particle without measuring its energy. For registrating the energy of the separate impulse, originated discharge should be extinguished.
Semi-conducting counter is a detector of particles, the mail element of what is crystal detector. Semi-conducting counters are very effective, they can work in the magnetic fields. But the little thickness of the workspace of semi-conducting counters doesn't allow to use them for measuring of the high-energy particles.
Wilson (cloud) chamber (1912) is the oldest and (up to 50-60-s) the only kind of the tracking detector. The Soviet scientist D. V. Scobelcyn (1892-1988) has enlarged the abilities of Wilson chamber; he had put it into a strong electromagnetic field (1927). We can find out the type of the charge of a particle, its energy and mass. The lack of Wilson chamber is its short working time and laboriousness of the result processing.
Diffusion (cloud) chamber (1936) is a sort of Wilson chamber.
Bubble chamber (1952 american physician D. Glazer (1926)). In the bubble chamber the labour substance is superheated liquid. The bubble chamber works cyclically. The size of bubble chamber is like Wilson chamber, but their effective volume is much more bigger, because liquid is thicker than gas. This allows to use bubble chambers for examining long chains of birth and decay of the high-energy particles.
Nuclear emulsions (1927 The Soviet physician L.V. Mysovsky (1888-1939)) is a simple tracking detector of the charged particles. Photoemulsions are used for examining the reactions that are evoken by the particles accelerators of superhigh energies and in cosmic rays.
Spark chambers are a set of a large quantity of a small counters. That's why its information comes out immediately, without the further processing, and at the same time has the characteristics of a track detector.

Subrange	The position of the handhold of the switching unit	Scale	The unit	The range
I	Õ200	0-200	Ð/÷	5-200
II	Õ1000	0-5	milliroentgen/hour	500-5000
III	Õ100	0-5	milliroentgen/hour	50-500
IV	Õ10	0-5	milliroentgen/hour	5-50
V	Õ1	0-5	milliroentgen/hour	0,5-5
VI	Õ0.1	0-5	milliroentgen/hour	0,05-0,5