The validity of the exponential law of attenuation for the beam of gamma radiation in depending on the thickness and type of material of the absorber

Pri proračunu i projektovanju strulturalne zaštite od zračenja potrebno je na osnovu poznavanja interakcija koje karakterišu prolaz različitih vrsta zračenja kroz materijal izvući zaključke o prolasku čestica ili kvanata zračenja kroz apsorbere različitih debljina, geometrija, izrađene od različitih materijala. U ovom radu ispituje se važenje eksponencijalnog zakona atenuacije snopa gama zračenja u zavisnosti od debljine i vrste materijala apsorbera. Kao apsorberi su korišćeni aluminijum i olovo. Eksperimentalni podaci su pokazali opseg vrednosti površinske gustine i debljine apsorbera u kome važi eksponencijalni zakon slabljenja inteziteta gama zračenja u geometriji uzanog snopa, kao i opseg vrednosti površinske gustine i debljine apsorbera u kom je neophodno uračunati faktor nagomilavanja.The calculation and design of radiation protection shielding should be based on the interactions that characterize the passage of various types of radiation through the material to draw conclusions about the passage of particles or quanta of radiation through absorbers of different thickness, geometry, made of different materials. This paper examines the validity of the exponential law of attenuation for a beam of gamma radiation, depending on the thickness and type of material of the absorber. Aluminium and lead were used as absorbers. Experimental data showed a range of values of the surface density and the thickness of the absorber in which the exponential law of attenuation of gamma rays can be applied in the narrow-beam geometry, as well as the range of values of the surface density and the thickness of the absorber where it is necessary to include the build-up factor

Comparison of experimental and simulated responses of TL and OSL dosimeters in poly-energetic and multi-directional photon radiation fields

The aim of this paper is to examine the energy and angular responses of thermoluminescent (LiF:Mg,Ti and LiF:Mg,Cu,P) and optically stimulated luminescent (Al2O3:C) dosimeters with experimental measurements and Monte Carlo simulations. Nine radiation qualities, with mean energies ranging from 33 keV to 1.25 MeV, and five angles of incidence, between 0° and 80°, were used to conduct this analysis. The IEC 62387:2020 international radiation protection standard was used as the dosimeter response measure of quality. The experimental and simulated data exhibit that the dosimeter responses meet the standard's criteria, with certain exceptions on lower energies

Comparison of the Angular Response of Thermoluminescent and Optically Stimulated Luminescent Personal Dosimeters

Determination of the angular dependence of thermoluminescent (TL) and optically stimulated luminescent (OSL) dosimeters is of great importance for their application in poly-energetic multidirectional photon radiation fields. In order to determine the angular dependence of the dosimeter responses for different photon energies, the dosimeters were mounted on an ISO water slab phantom, irradiated in two narrow beam X-ray qualities (N-40 and N-80) and in one gamma ray quality (S-Cs), defined in IAEA SRS 16. The angles of incidence ranged from 0° to 60°, with an increment of 20°. Two types of TL dosimeters were used: MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P) and one type of OSL dosimeters, InLight (Al2O3:C). The two types of TL dosimeters have shown a similar deviation from their 0° responses for all the used radiation qualities, while the OSL dosimeters have shown a greater deviation from the reference values for the gamma radiation quality

Low-energy X-ray Angular Response of Optically Stimulated Luminescent Dosimeters

Following the requirements of radiation protection international standards, passive dosimetry systems are type tested, which includes the angular dependence. As it represents one of the most important dosimeter characteristics, the angular dependence of commercially available optically stimulated luminescent dosimeters has been examined in this paper. The empirically determined air kerma to the personal dose equivalent conversion coefficients decrease as the angle of incidence increases. It was anticipated that the dosimeter response would show a similar behavior. This expectation has been confirmed for all the used angles of incidence and energies of the primary X-ray beam, except for the 80° angle of incidence and the 33 keV and 48 keV mean photon energies, where an increase in the angular response has been observed

Energy, Angular and Dose-rate Dependence of the GM Survey Meter Response

—Survey meters represent common radiation protection instruments used for ambient monitoring. They estimate the effective dose of occupationally exposed personnel, by measuring the ambient dose equivalent. A performance testing of a Geiger-Müller tube-based survey meter was realized in this paper. The energy and the dose rate dependence were determined for different thicknesses of lead tube wrappings, in order to achieve the optimal energy compensation. The energy response for higher-energy photons slightly improved by applying these filters, while it significantly worsened for low-energy X-rays. The angular dependence was tested in terms of angular response and its symmetry for different radiation qualities

Comparison of the Energy and Angular Responses of Thermoluminescent and Electronic Personal Dosimeters

Determination of the response of thermoluminescent and electronic personal dosimeters as a function of photon energy and angle of incidence has a crucial impact on their application in poly-energetic multidirectional photon radiation fields. In the experimental part of this paper, in order to determine the energy dependence of the dosimeter responses, the dosimeters were mounted on an ISO slab phantom, irradiated in X and gamma ray fields, defined in the IAEA SRS 16, within the energy range of 33 keV - 1,25 MeV. Tested dosimeters have not shown an adequate response in the low photon energies relative to their Cs-137 responses, while in the middle and high energy photon ranges they performed well and have shown a deviation relative to their Cs-137 responses up to ±20%. In order to determine the angular dependence of the dosimeters the N-200 narrow beam radiation quality has been used. The angles of incidence for which the dosimeters were tested range from 0° to 80°, with an increment of 20°. Most of the dosimeters have behaved as expected, except for certain dosimeters due to their significant increase in response caused by the influence of the scattered radiation

Establishing Standard X-ray Narrow-beam Radiation Qualities in the Secondary Standard Dosimetry Laboratory

Prior to performing calibrations in the Secondary Standard Dosimetry Laboratory (SSDL), standard radiation qualities must be determined in order to accurately assess the absorbed dose of occupationally exposed personnel and to evaluate the performance of radiation measurement instruments. Due to the energy dependence of the calibration factor and the air kerma to the personal dose equivalent conversion factor, it is of great importance to properly establish standard radiation qualities. Radiation qualities can be characterized by determining their photon energy distributions, or by using the Xray tube voltage and the first and second half-value layers. In this paper, the half-value layers were determined by varying the thicknesses of the additional filtration absorbers. The calculated values show a deviation from the ISO standard values not greater than 6%

Response of TL and OSL passive personal dosimetry systems in poly-energetic and multi-directional photon radiation fields

The aim of this paper is to examine the energy and angular responses of thermoluminescent dosimeters containing either MTS-N (LiF:Mg,Ti) or MCP-N (LiF:Mg,Cu,P) detector materials, and of the InLight optically stimulated luminescent dosimeters containing Al2O3:C detectors. Ten radiation qualities, with mean energies ranging from 24 keV to 1.25 MeV, and five angles of incidence, between 0° and 80°, were used for this purpose. The dosimeter response measure of quality were the IEC 62387 requirements. The experimental results show that the MTS-N-based and the InLight dosimeters performed in line with the standard's criteria. On the other hand, the MCP-N-based dosimeters exhibited a pronounced under-response around the energy of 120 keV, which resulted in deviations from the standard's conditions for both the energy and angular responses. © 2019 Elsevier Lt