Gamma Radioisotope Sources Research Articles

Thermodynamics kinetics of boron carbide under gamma irradiation dose

In this paper, high purity boron carbide samples were irradiated by [Formula: see text]Co gamma radioisotope source (0.27 Gy/s dose rate) with 50, 100, 150 and 200 irradiation hours at room-temperature. The unirradiated and irradiated boron carbide samples were heated from 30[Formula: see text]C to 1000[Formula: see text]C at a heating rate of 5[Formula: see text]C/min under the argon gas atmosphere of flow rate 20 ml/min. Thermogravimetric (TG) and Differential Scanning Calorimetry (DSC) were carried out in order to understand the thermodynamic kinetics of boron carbide samples. The weight kinetics, activation energy and specific heat capacity of the unirradiated and irradiated boron carbide samples were examined in two parts, T [Formula: see text] 650[Formula: see text]C and T [Formula: see text] 650[Formula: see text]C, according to the temperature. The dynamic of quantitative changes in both ranges is different depending on the irradiation time. While the phase transition of unirradiated boron carbide samples occurs at 902[Formula: see text]C, this value shifts upto 940[Formula: see text]C in irradiated samples depending on the irradiation time. The activation energy of the unirradiated boron carbide samples decreased from 214 to 46 J/mol in the result of 200[Formula: see text]h gamma irradiation. The reduction of the activation energy after the irradiation compared to the initial state shows that the dielectric properties of the irradiated boron carbide samples have been improved. After the gamma irradiation, two energy barrier states depending on the absorption dose of samples were formed in the irradiated samples. The first and second energy barriers occurred in 0.56–0.80 and 0.23–0.36 eV energy intervals, respectively. The existence of two energy levels in the irradiated boron carbide indicates that the point defects are at deep levels, close to the valence band.

Changes in gamma attenuation behaviour of sol-gel derived CIGS thin film irradiated using Co-60 radioisotope

Copper indium gallium (di) selenide-Cu(In, Ga)Se2 (CIGS) thin films were fabricated on soda-lime silicate glass substrates using a layer-by-layer sol-gel dip-coating method. The irradiation procedure was handled using a certified Co-60 radioisotope at two different absorbed dose levels (at 0,03 and 0,05 Gray (Gy)) to examine the enhancements of optical and electrical properties of the CIGS thin films. Cs-137 (with 0,662 MeV) and Co-60 (with ∼1,25 MeV) radioisotopes were used to evaluate the effect of the absorbed dose on CIGS thin films with different thicknesses by the gamma transmission technique. The irradiated CIGS thin films exhibited an improved optical band gap and electrical resistivity at the optimal layer thickness. This improvement occurs due to the enhancement of crystalline properties in comparison with those of non-irradiated CIGS thin films. The CIGS thin film of ∼300 nm (11 layers) thickness was suitable for comparing changes in the linear attenuation coefficient after the irradiation process at two different absorbed dose levels. In the experiments, the gamma transmission technique was utilized to investigate the gamma attenuation properties of non-irradiated and irradiated CIGS thin films at different thicknesses against Cs-137 (with 0,662 MeV) and Co-60 (with ∼1,25 MeV) gamma radioisotope sources. The irradiation process and the increase of thickness of CIGS thin films caused a higher linear attenuation coefficient, higher absorption and improvement in electrical conductivity. These results demonstrate the suitability of these materials for solar cell applications in aerospace technology, especially for high-altitude flight operations.

Gamma Attenuation Properties of Some Aluminum Alloys

In the present work, several commonly used aluminum alloys were investigated for their protective properties against gamma radiation. The gamma transmission technique was used to study the gamma attenuation behavior of the alloys. Cs-137 (0.662 MeV) and Co-60 (1.25 MeV) gamma radioisotope sources, which have relatively medium and high gamma energy levels, were used as gamma sources. The linear and mass attenuation coecients of the aluminum alloys were measured. The mass attenuation coecients of the samples were compared with the theoretical values which were calculated using XCOM computer code. The dierence between the experimental and theoretical values was below 5%. In addition half-value layer (HVL) values for the studied aluminum alloys were calculated using the linear attenuation coecients. The attenuation coecients of the dierent aluminum alloys were compared. The biggest HVL was observed for 1050 alloy, for both gamma isotope sources, which means the smallest gamma attenuation capability among the studied alloys. It is concluded that the alloys were applicable for the gamma radiation shielding applications.

Investigation on the Behaviours of TiB2 Reinforced B4C-SiC Composites Against Co-60 Gamma Radioisotope Source

In the present study, the gamma attenuation behaviours of the Titanium diboride (TiB2) reinforced boron carbide (B4C)-silicon carbide (SiC) composite materials were investigated against Co-60 gamma radioisotope source. In the experiments TiB2 unreinforced and 2% and 4% TiB2 (by volume) reinforced B4C-SiC composite materials were used. In the composite materials B4C/SiC ratio has been realized as 6/4 by volume. The linear and mass attenuation coefficients of the samples were carried out for Co60 gamma radioisotope source which has two energy peaks (1.17 and 1.33 MeV). Then mass attenuation coefficients and half-value thicknesses (HVT) of the materials were calculated. Experimental mass attenuation coefficients were compared with the theoretical values which were calculated from XCOM computer code. Furthermore HVTs of the samples were evaluated and compared each other. It has been seen that the experimental and theoretical mass attenuation coefficients are closed to each other and differences are under 10 percent. In addition, TiB2 reinforced B4C-SiC composites have smaller HVTs than unreinforced one. Moreover 4% TiB2 reinforced B4C-SiC composite has smaller HVT than the 2% reinforced sample. Reinforcing TiB2 and increasing TiB2 ratio increase the gamma attenuation property of the B4C-SiC composites against Co-60 gamma radioisotope source.

Gamma and neutron attenuation behaviours of boron carbide–silicon carbide composites

In this study, the gamma and neutron attenuation behaviors of pure boron carbide and boron carbide–silicon carbide composites which include three different silicon carbide ratios (20%, 30%, and 40%) by volume were investigated against Cs-137, Co-60 gamma radioisotope sources and Pu–Be neutron source. Transmission technique was used in the experiments to investigate the gamma and neutron attenuation properties of the materials. Linear and mass attenuation coefficients of the samples were determined for 0.662 (Cs-137) and 1.25MeV (Co-60) energetic gamma rays. In addition the total macroscopic cross-sections (∑T) were calculated for the materials against Pu–Be neutron source. Theoretical mass attenuation coefficients were calculated from XCOM computer code. The experimental and theoretical mass attenuation coefficients were compared and evaluated with each other. In addition half value thickness (HVT) calculations were carried out by using linear attenuation coefficients and total macroscopic cross-sections. The results showed that increasing silicon carbide ratio decreases HVTs against Cs-137 and Co-60 gamma radioisotope sources whereas increases HVTs against Pu–Be neutron source. The mass attenuation coefficients were compatible with the theoretical (XCOM) values. Increasing silicon carbide ratio in boron carbide–silicon carbide composites causes higher gamma attenuation and lower neutron attenuation values.

Evaluation of Gamma Penetration through Plain Carbon Steels

In this study, 1010, 1040, 1050 and 1090 carbonized steels were investigated against gamma radioisotope sources on their gamma attenuation properties. Co-60, Cs-137 and Ir-192 gamma radioisotopes which are commonly used in industrial applications were used in the experiments. Half-value layers were carried out for studied carbonized steels against all studied gamma radioisotopes. In addition, the linear and mass attenuation coe cients were determined for each carbonized steels at di erent gamma radioisotope sources. The theoretical mass attenuation coe cients were calculated from XCOM computer code for all samples at speci c energies of Co-60, Cs-137 and Ir-192 gamma sources. The theoretical and experimental results were compared with each other.

Comparison of Lead and WC-Co Materials against Gamma Irradiation

According to RoHS (Restriction of Hazardous Substances) directive of European Union it is restricted using lead in many equipment and applications. It is possible to enlarge the restriction of lead usage in some other applications which is including some of nuclear applications in the future. Therefore new materials or systems need to be developed instead of lead as radiation shielding materials and/or collimators. In this study pure tungsten, tungsten carbide-cobalt (WC Co) materials were investigated against gamma radiation. For gamma radiation Cs-137 and Co-60 gamma radioisotope sources were used. The linear and mass attenuations were calculated. The experimental results were compared with XCOM computer code. Usage possibilities of WC Co instead of lead in nuclear applications as gamma shielding material were discussed. It has been investigated that the linear gamma attenuation coe cients of lead and WC Co are very close to each other. Therefore it could be said that WC Co materials is an alternative promising material which could be used instead of lead as gamma shielding material and/or collimator.

An investigation on gamma attenuation behaviour of titanium diboride reinforced boron carbide–silicon carbide composites

In this study, titanium diboride (TiB2) reinforced boron carbide–silicon carbide composites were investigated against Cs-137 and Co-60 gamma radioisotope sources. The composite materials include 70% boron carbide (B4C) and 30% silicon carbide (SiC) by volume. Titanium diboride was reinforced to boron carbide–silicon carbide composites as additive 2% and 4% by volume. Average particle sizes were 3.851µm and 170nm for titanium diboride which were reinforced to the boron carbide silicon carbide composites. In the experiments the gamma transmission technique was used to investigate the gamma attenuation properties of the composite materials. Linear and mass attenuation coefficients of the samples were determined. Theoretical mass attenuation coefficients were calculated from XCOM computer code. The experimental results and theoretical results were compared and evaluated with each other. It could be said that increasing the titanium diboride ratio causes higher linear attenuation values against Cs-137 and Co-60 gamma radioisotope sources. In addition decreasing the titanium diboride particle size also increases the linear and mass attenuation properties of the titanium diboride reinforced boron carbide–silicon carbide composites.

Investigation of Behaviour of Titanium Diboride Reinforced Boron Carbide-Silicon Carbide Composites against Cs-137 Gamma Radioisotope Source by Using Gamma Transmission Technique

Boron carbide is a material which has wide application areas in industry including nuclear technology. Titanium diboride reinforced boron carbide‐silicon carbide composites were studied for searching of the behaviour against the gamma ray. It has been adopted that depending on their properties such improved materials can be used in nuclear technology. For the investigation of the gamma radiation behaviour of these materials, Cs-137 radioisotope was used as gamma source in the experiments which have a single gamma-peak at 0.662 MeV. Gamma transmission technique was used for the measurements. Dierent reinforcing ratios, titanium diboride reinforced boron carbide‐silicon carbide composites were evaluated in relation to gamma transmission and the results of the experiments were interpreted and compared with each other. It could be understood that the increasing ratio of titanium diboride in boron carbide‐silicon carbide composites causes higher hardness, strength and linear attenuation coecient values but decrease the mass attenuation coecient.

Determination of Gamma Transmittance and Density Assessment for Al Doped ZnO Thin Films by Using Gamma Transmission Technique

The aim of this study is to investigate the structural changes of Al doped ZnO thin films with gamma transmission technique with Cs-137 gamma radioisotope source. Gamma transmittance and gamma absorption coefficient, (1/mm) were investigated with the increase Al (at.%) concentration. Hence it can be possible to assess the density for Al doped ZnO thin films.

Dosimetric evaluation of gamma doses using irradiated lead–alkali–silicate glass

Lead–alkali–silicate glass samples were irradiated with 0.998–35.939 kGy dose levels using a 60Co gamma radioisotope source. The colour of the lead–alkali–silicate glass turned to brownish orange with absorbed dose. Radiation-induced changes in the properties of visible light transmittance and absorbance were examined between wavelengths of 380 and 1500 nm using a spectrophotometer. Changes in the optical colour parameters were determined and compared with those of unexposed glasses and it is shown that they can be used as radiation dosimeters, especially for medical dosimeters.

Gamma irradiation facilities

A review is presented on the status and problem of gamma irradiation facilities for radiation processing. Requirements for the radioisotope source in the radiation processing and its comparison with electron accelerator are discussed. The gamma radioisotope source has speciality in the process of thicker products and source design, though it is inferior on the cost of radiation output. Problems on irradiation facilities such as storage and transportation of the source, the damage of materials used, and dosimetry are discussed. The gamma irradiation facilities for the radiation processing in Japan are introduced.