Effect Of Gamma Doses Research Articles

Effect of gamma dose on dielectric and optical properties of ZnO/PVA.

Effect of gamma dose on dielectric and optical properties of ZnO/PVA.

Gamma-ray-induced changes in the radiation shielding, structural, mechanical, and optical properties of borate, tellurite, and borotellurite glass systems modified with barium and bismuth oxide

This study explores the impact of different gamma-ray doses (2.5, 50, and 100 kGy) and TeO2 ratios on the structural, optical, mechanical, and radiation-shielding properties of borate glass systems modified with barium and bismuth oxide. Various physicochemical instruments were utilized to investigate these properties. The samples’ colors changed for all glasses with gamma-ray irradiation, and the color became more darkened with increasing doses. The Fourier transform infrared (FTIR) and Raman results confirmed the glass structure stability with different doses, but they offer a variation in intensity compatible with the bandgap energy results. Borate glass has the highest mechanical properties compared to the tellurite and borotellurite glass systems. Concomitantly, a gamma dose of up to 2.5 kGy enhanced the mechanical properties of all glass systems and then showed a reduction. Moreover, borate glass has the highest thermal stability compared to the tellurite and borotellurite glass, and gamma doses showed a slight variation. The tellurite and borate glasses recorded the highest and lowest band gaps, respectively. Experiments on the radiation-shielding properties and the effect of gamma doses were performed. The gamma-ray doses affected the mass attenuation coefficient (MAC) values of the tellurite and borotellurite glass samples. In contrast, the borate glass samples exhibited the highest MAC withstanding against gamma doses, and MAC values showed no variation with changing gamma doses. In summary, borate glass has the highest thermal stability, structural and mechanical properties, and stability in radiation-shielding features, which shows promise as an alternative for use in the radiation-shielding field.

64Cu enrichment using the Szilard-Chalmers effect – The influence of γ-dose

Cu is an important trace metal which plays a role in many biological processes. The radioisotope 64Cu is often used to study such processes. Furthermore, 64Cu finds applications in cancer diagnostics as well as therapy. For all of these applications 64Cu having high specific activity is needed. 64Cu can be produced in cyclotrons or in nuclear reactors. In this paper we study the effect of gamma dose on the production of 64Cu according to the Szilard-Chalmers reaction using Cu(II)-phthalocyanine as a target. For this purpose, irradiations were performed in the nuclear reactor of the Delft University of Technology using a novel irradiation facility helping to limit the dose produced by gammas present in the reactor pool. The obtained 64Cu activity yield was in general above 60% in accordance to the theoretical expected value. An increase in gamma dose has no significant influence on the obtained activity yield but increases the loss of Cu from Cu(II)-phthalocyanine up to 0.9% and hence decreases the specific activity that can be obtained. However, without optimisation, when reducing the gamma dose specific activities in the order of 30 TBq/g can be achieved.

Novel formation mechanism of Ag/PANI/PVP core-shell nanocomposites

Recently, polymer-inorganic nanocomposites core shells have attracted great attention as new materials because of their novel mechanical, electrical, and optical properties. In this article, we report a simultaneous synthesis of polyaniline (PANI) nanoparticles and Silver (Ag) nanoparticles to form Ag/PANI nanocomposite core-shell embedded in polyvinilpirrolidone (PVP) by using hybrid chemical and gamma-irradiation oxidation process of aniline and reduction of Ag ions, respectively in the presence of dodecylbenzenesulphonic acid (DBSA). The mechanism of formation of Ag/PANI/PVP core-shell is proposed in this article. In addition, the effects of gamma-dose and Ag ions concentration on structural, and optical, properties of the nanocomposites PVP/PANI/Ag core-shell were carefully examined. The structural and morphological studies show the presence of PANI with regular granular nanostructure as a shell with a diameter of 20 nm and Ag nanoparticles with spherical shape as a core and diameter less than 10 nm. The average particle size of my modified Ag/PANI nanoparticles decreased with increasing dose and decreasing of precursor concentration due to increase of nucleation process over aggregation process during gamma irradiation. The UV–Visible Spectroscopy, Scanning Electron Microscopy (SEM) and the TEM showed appreciated result of formation Ag/PANI which is going to be discussed in current studies.

Simulation and design of individual neutron dosimeter and optimization of energy response using an array of semiconductor sensors

Abstract Many researches have been done to develop and improve the performance of personal (individual) dosimeter response to cover a wide of neutron energy range (from thermal to fast). Depending on the individual category of the dosimeter, the semiconductor sensor has been used to simplify and lightweight. In this plan, it’s very important to have a fairly accurate counting of doses rate in different energies. With a general design and single-sensor simulations, all optimal thicknesses have been extracted. The performance of the simulation scheme has been compared with the commercial and laboratory samples in the world. Due to the deviation of all dosimeters with a flat energy response, in this paper, has been used an idea of one semi-conductor sensor to have the flat energy-response in the entire neutron energy range. Finally, by analyzing of the sensors data as arrays for the first time, we have reached a nearly flat and acceptable energy-response. Also a comparison has been made between Lucite-PMMA (H 5 C 5 O 2 ) and polyethylene–PE (CH 2 ) as a radiator and B 4 C has been studied as absorbent. Moreover, in this paper, the effect of gamma dose in the dosimeter has been investigated and shown around the standard has not been exceeded.

Thermoluminescence behaviour of GdAlO3:Yb3+ under gamma exposure

Thermoluminescence behaviour of Yb3+ doped GdAlO3 was studied for solution combustion synthesised phosphor. The TL glow curve was recorded under gamma radiation. The Tl glow curve was recorded for various heating rate for constant 0.25 kGy gamma radiation to optimize the heating rate. The optimized heating rate was obtained at 4 °C s−1. The effect of gamma dose on TL behaviour of the phosphor was studied by recording the TL for different gamma radiation dose from 0.25 to 1.25 kGy. For lower gamma dose the TL glow peak consists kinked peak with Tm at 397 and 432 K. As the gamma dose increases the Tm at lower temperature side vanished and the TL glow curve consists only one peak of higher temperature i.e. 432 K. To explain the variation in TL behaviour with variable gamma dose the TL glow curve for different gamma dose was analysed by using computerized glow curve deconvolution method. The kinetic parameters were calculated for all the deconvoluted peaks by using Chen’s peak shape method. Activation energy for higher temperature peak is more than lower temperature peak due to deeper and shallow traps respectively.

The Influence of Fire Retardant (Aluminum Hydroxide) Concentrations on EPDM Rubber Under Ɣ Irradiation

EPDM is the most commonly used type of rubbers for cables insulation. In order to improve the EPDM insulation rubber performance, many additives can be used. Aluminum hydroxide is used as a fire retardant because it is safe and cheap and reduces the amount of smoke produced in fires. In this study, two concentrations (10 and 20 phr) of aluminum hydroxide ATH were used to improve EPDM insulation properties and to prolong its operational life. The effect of gamma doses (up to 600 KGy) on the mechanical, physical and thermal properties of EPDM/ ATH has been investigated. The results of the present study show that the optimum concentration of ATH is 20phr.

Gamma induced effects on structural, optical and electrical properties of n-TiO2/p-Si heterojunction

This study reports the fabrication of n-TiO2/p-Si heterojunction by deposition of TiO2 thin films on p-Si substrate. The effect of gamma doses on structural, optical and the current–voltage (I–V) characteristics of n-TiO2/p-si heterojunction were studied. Measurements performed with the aid of X-ray diffraction revealed that deposited thin film was composed of nanocrystalline mixture of anatase and rutile phases, which change to TiO2 anatase phase after irradiation. Optical properties were evaluated based on diffuse reflectance and photoluminescence measurements. The I–V characteristics were measured to investigate the heterojunction effects at different gamma doses. Some parameters including ideality factor (n), barrier height (ΦB) and series resistance (Rs) were calculated from I–V characteristics before and after irradiation. Experimental results indicated that structural, optical and electrical parameters of n-TiO2/p-si heterojunction were influenced by the gamma radiation doses.

Analytical modeling for gamma radiation damage on silicon photodiodes

Radiation-induced damage in PIN silicon photodiode induces degradation of the photodiode parameters. In this work, by presenting an analytical model, the effect of gamma dose on the dark current in a PIN photodiode array was investigated. Geant4 was used to obtain the damage constant as a result of primary incident particle fluence and NIEL distribution calculations. Experimental measurements as well as numerical simulation of the semiconductor with ATLAS were carried out to verify and parameterize the analytical model calculations. A reasonable agreement has been found between analytical results and experimental data for BPX65 silicon photodiodes irradiated by a Co-60 gamma source at total doses up to 500krad under different reverse voltages. Moreover, the results showed that the dark current of each photodiode array pixel has considerably increased by gamma dose irradiation.

Dose Response and FWHM Properties of Dyed Poly Vinyl Alcohol-Irradiated with Gamma-Rays

The effects of gamma irradiation on absorption properties of Carbol Fuchsin (CF) with crystal violet dyed Poly Vinyl Alcohol (PVA) blended for possible use in dosimetry and measurement of radiation dose in gamma rays have been studied using UV-Visible spectrophotometer method. The films were irradiated to accumulated doses from (10 to 70) Gy using Co60 gamma ray source at a constant dose rate. The absorption spectra were measured using UV-Visible spectrophotometer in the wave length range (200 to 900) nm, resulting in a decrease of the absorbance at 560 nm band peak with increasing dose. Regarding to the IR transmittance it’s appearing that for the samples with crystal violet the band at 1716 divided two small bands which become obvious for the irradiated one which indicate also the effect of gamma doses. In this study, the less Full Width at Half Maximum (FWHM), the better is the dosimeter. The FWHM due to sharpness in the band peak and this is useful for determine the fine dosimeter.

Bioremediation of trace cobalt from simulated spent decontamination solutions of nuclear power reactors using E. coli expressing NiCoT genes

Removal of radioactive cobalt at trace levels (approximately nM) in the presence of large excess (10(6)-fold) of corrosion product ions of complexed Fe, Cr, and Ni in spent chemical decontamination formulations (simulated effluent) of nuclear reactors is currently done by using synthetic organic ion exchangers. A large volume of solid waste is generated due to the nonspecific nature of ion sorption. Our earlier work using various fungi and bacteria, with the aim of nuclear waste volume reduction, realized up to 30% of Co removal with specific capacities calculated up to 1 microg/g in 6-24 h. In the present study using engineered Escherichia coli expressing NiCoT genes from Rhodopseudomonas palustris CGA009 (RP) and Novosphingobium aromaticivorans F-199 (NA), we report a significant increase in the specific capacity for Co removal (12 microg/g) in 1-h exposure to simulated effluent. About 85% of Co removal was achieved in a two-cycle treatment with the cloned bacteria. Expression of NiCoT genes in the E. coli knockout mutant of NiCoT efflux gene (rcnA) was more efficient as compared to expression in wild-type E. coli MC4100, JM109 and BL21 (DE3) hosts. The viability of the E. coli strains in the formulation as well as at different doses of gamma rays exposure and the effect of gamma dose on their cobalt removal capacity are determined. The potential application scheme of the above process of bioremediation of cobalt from nuclear power reactor chemical decontamination effluents is discussed.

Effect of gamma irradiation on the optical spectra of undoped, Mg-doped, and Gd-doped LiNbO3 single crystals

We have measured the optical spectra of gamma-irradiated lithium niobate crystals of different compositions: nominally undoped and doped with rare-earth (Gd) and alkaline-earth (Mg) metals in the range 0.003–0.27 wt %. The difference in behavior between gamma-irradiated and vacuum-annealed nominally undoped lithium niobate single crystals has made it possible to elucidate the mechanisms underlying the formation of electronic and point defects in the crystals and to develop a model for the processes involved. The effects of gamma dose, doping level, and the nature of the dopant on the optical absorption of gamma-irradiated doped lithium niobate single crystals are analyzed.

The effect of gamma-irradiation on the activation energy of bulk and track etching in CR-39 plastic track detector

Systematic studies have been made concerning the effects of gamma dose on the track registration properties of CR-39 plastics solid-state track detector (SSTD). The changes in bulk and track etch rates as well as in sensitivity due to gamma rays in the dose range of 0 – 10 3 kGy at different temperatures (338–353 K) are discussed on the basis of degradation and cross-linking mechanisms. The increase in bulk and track etch rates with gamma dose has been found while a rapid fall off in sensitivity at higher dose is also seen. From these measured values of bulk and track etch rates, the activation energies associated with them have also been calculated which show a decrease from unirradiated to 10 3 kGy gamma dose.

Effect of high gamma doses on the etching behaviour of different types of PADC detectors

Polyallyldiglycol carbonate (PADC) detectors were exposed to different doses of gamma radiation ranging from 10 1 to 10 6 Gy from a 60Co source. The effect of gamma doses on etch-rates were studied. Etch-rate values were found to increase at the dose of 10 6 Gy for all types of PADC detectors. The influence of gamma exposure on sensitivity and etching efficiency of these detectors was also determined. The experimental results are presented and discussed.

Chromosome elimination in asymmetric somatic hybrids: effect of gamma dose and time in culture

Mesophyll protoplasts of a kanamycin-resistant line of Nicotiana plumbaginifolia were gamma-irradiated and fused with mesophyll protoplasts of N. tabacum plants bearing the sulfur mutation. Hybrid calli were recovered by selection on media containing kanamycin. In one group of experiments, the degree of elimination of donor (N. plumbaginifolia) genetic material in the hybrid calli was assessed by dot-blot hybridization using a N. plumbaginifolia-specific repetitive-DNA sequence as a probe. The elimination of donor DNA was found to increase with increasing gamma dose for all doses tested (5-50 krad). Elimination of donor DNA was also found to continue in the calli for the first 12 months in culture. The degree of chromosome elimination was quite variable; for a 50-krad dose, some hybrids were recovered that retained less than 15% of the donor genome, whereas others retained nearly 50%. In a second set of experiments, the degree of donorchromosome elimination was assessed from the fraction of hybrid calli that exhibited complementation of the Su phenotype due to retention of a wild-type Su allele of the donor. When N. plumbaginifolia protoplasts were inactivated by treatment with iodoacetate, rather than gamma irradiation, all the hybrid calli were green. However, when the donor protoplasts were inactivated by irradiation, the fraction of hybrid calli that were able to complement the Su mutation decreased with increasing gamma dose; for a 50-krad dose only 40% of the hybrid calli were green. From these data, the degree of radiation-induced donor-chromosome elimination was calculated and was found to agree closely with that measured by dot-blot hybridization. We conclude that radiation-induced elimination of donor chromosomes increases with gamma dose and time in culture in N. tabacum (+)N. plumbaginifolia hybrids, but that donor-chromosome elimination is an inherently variable process.

Gamma-ray response function of some polymeric nuclear track detectors

The effect of gamma dose on the bulk-etch rate measurements for some gamma-irradiated polymeric nuclear track detectors was extensively studied. Various plastic samples of CR-39 allyl diglycol carbonate, Makrofol-E and Lexan polycarbonates were used and exposed to gamma doses up to 30.0 Mrad. The bulk-etch rate ratioVBD/VBO, i.e. the bulk-etch rate of irradiated samples to the unirradiated ones, was measured at the most recommended optimum etching conditions. Fading behaviour of irradiated CR-39 samples was also studied at room temperature and for a duration of up to 8 days. It was found that the etch-rate ratio for the CR-39 specimens was dose-dependent. In contrast, the polycarbonate samples showed an extremely weak response to gamma irradiation. The results of the present work reflected great evidence of the gamma dosimetric potential of CR-39 plastic detectors, which can indeed be recommended as gamma-dosimeters within the studied dose range.

The effect of gamma dose on the alpha response of CR-39

Abstract The effect of gamma irradiation on the alpha-particle track response of CR-39 is investigated. The effects are dramatic above doses of 500Krad. The alpha-particle tracks in highly dosed plastic exhibit a ‘threshold’ residual range below which the track etching appears to saturate. The effects can be simulated by the use of a suitable VT(R) vs range curve and is therefore not a ‘skin’ effect. The effects appear to be due to the addition of the two doses, the effects being present for alpha dose + gamma dose and gamma dose + alpha dose. The average track etch rates VT/VB, remain constant up to 500Krad but then exhibit a fall-off at higher doses. The observations have relevance for neutron spectrometry and dosimetry measurements where large gamma fields may be present. The bulk etching behaviour is also investigated. The change in bulk etching rate is too small to be of any value in a gamma dosemeter for doses below 100Krad.

The effect of gamma dose on oxide films on zirconium and zircaloy-2 and its relevance to corrosion

Oxide films between 2000 and 7000 A thick, on Van Arkel zirconium and Zircaloy-2, were irradiated to pure gamma doses of up to 2 × 10 9 rad; and two films were exposed to 10 17 nvt of fast neutrons. The electrical conductivity and capacitance (100 c/sec to 20 000 c/sec) and optical absorption (2000 to 20 000 Å) of these films were indistinguishable from those of unirradiated controls. This was taken to indicate that < 10 19 ions/cm 3 were displaced by the radiation, A value of < 10 17 ions/cm 3 is calculated from damage theory. It is reasoned that reactor gamma radiation is unlikely to have an appreciable effect on electron or ion transport in Zircaloy-2 corrosion films a few thousand Angström thick. Hence, if either electron or ion transport control corrosion in such films, reactor gamma radiation should not affect corrosion.