[en] The cavity theory is modified to obtain such a formula for determination of absorbed dose using ionization chamber in high energy particle beams, which (formula) contains only one factor dependent on ionization chamber wall materials, and this factor can be determined experimentally. The energy expended to creation an ion pair and the restricted stopping power ratio are correlated with a recombination index of radiation quality, which also can be found experimentally in the investigated radiation beams. Accuracy of the absorbed dose determination in therapy beams of particles with energy of some hundreds MeV, by means of the method proposed, is equal to about 5%. 39 refs.; 3 figs.; 1 tab

[en] An instrument for measurement of ionizing radiation quality factor containing recombination chamber with 3 electrodes, in which measuring electrode is connected with imput of electrometric amplifier, is described. There are two gas areas of different volume and profitably with volume ratio from 0,75 to 0,95 between two electrodes: higher and lower. The higher one is connected with output of electrometric system. The instrument enables a continuous and direct measurement of quality factor without extra calculations. 1 fig. (A.S.)

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No abstract available

[en] Saturation curves have been determined for a high pressure parallel plate ionization chamber exposed to gamma radiation from ¹³⁷Cs source of alpha radiation from ²²²Rn. The chamber was filled with carbon dioxide at pressure varying from 100 to 1000 kPa. Ion collection efficiences for local recombination conditions have been determined. It was found that ion collection efficiency more than five times higher for gamma radiation as compared with that for alpha radiation is achievable at CO₂ - pressure higher than 500 kPa. (author)

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[en] The radiation effects of boron neutron capture therapy (BNCT) are associated with four-dose-compartment radiation field - boron dose (from ¹⁰B(n,α)⁷Li) reaction), proton dose from ¹⁴N(n,p)¹⁴C reaction, neutron dose (mainly fast and epithermal neutrons) and gamma-ray dose (external and from capture reaction ¹H(n,γ)²D). Because of this the relation between the absorbed dose and the biological effects is very complex and all the above mentioned absorbed dose components should be determined. From this point of view, the recombination chambers can be very useful instruments for characterization of the BNCT beams. They can be used for determination of gamma and high-LET dose components for the characterization of radiation quality of mixed radiation fields by recombination microdosimetric method (RMM). In present work, a graphite high-pressure recombination chamber filled with nitrogen, ¹⁰BF₃ and tissue equivalent gas was used for studies on application of RMM for BNCT dosimetry. The use of these gases or their mixtures opens a possibility to design a recombination chamber for determination of the dose fractions due to gamma radiation, fast neutrons, neutron capture on nitrogen and high LET particles from (n,¹⁰B) reaction in simulated tissue with different content of ¹⁰B. (author)

[en] Influence of an atomic composition of material surrounding the gas cavity on gas ionization has been investigated in medical beams of protons with the energy of 200 MeV and 660 MeV and neutrons with mean energy of 350 MeV. Data obtained permit to calculate the correction factors required for determination of dose absorbed in a phantom by means of real detectors. It is shown that corrections may be neglected for ionization chambers with organic material walls

[en] This paper is devoted to a description of a microcomputer controlled dose equivalent rate meter, based on a recombination principle and intended for routine use in radiation protection. The device displays, directly, the ambient dose equivalent rate H^*(10), the absorbed dose rate and the quality factor. The ionisation chamber of REM-2 type serves as a detector. An appropriate set of collecting voltages is sequentially applied to the chamber electrodes. Ions which have avoided initial recombination are collected at a capacitor connected to an electrometer. The the collected charge is registered in the computer memory. The ambient dose equivalent is calculated in real time, taking into account the dependence of the initial recombination of ions on linear energy transfer (LET). The device can be used in radiation fields of any composition, usually with an accuracy not worse than 30%. (orig.)

No abstract available