Ogleomar9811

Monte Carlo simulations (MCNP) were carried out to model suitable 252Cf-based gamma transmission and neutron attenuation geometries to evaluate the gamma-ray shielding features and neutron attenuation capabilities for Al2O3, MgF2, Fluental and AlF3, as fast neutron moderators of potential interest in 252Cf-based Born Neutron Capture Therapy (BNCT) facilities. The mass attenuation coefficient (μ/ρ), Half-Value Layer (HVL), Mean Free Path (MFP) and gamma transmission factor (I/Io) for Al2O3, MgF2, Fluental and AlF3 were simulated at gamma energies, 0.3 MeV, 0.364 MeV, 0.662 MeV, 1.25 MeV and 7.12 MeV. The MCNP simulated μ/ρ values were compared to theoretical XCOM values and good agreement was observed. The ratio of total thermal neutron flux to the total fast neutron flux (φ total thermal/φ total fast) and the total flux of gamma rays (φ total (n,γ) gamma) resulting from thermal neutron capture (n,γ) reactions, were simulated and compared as a function of thickness for the four sample moderators. The values of the effective fast neutron removal cross section ΣR (cm-1) for the four sample moderators were calculated and compared. In this study, we validated the feasibility of an energy weighted algorithm that highlights a characteristic area including the Compton edge as a single peak in a proof-of-principle radiation portal monitor system with a plastic scintillator measuring 50 × 100 × 5 cm3. We measured the energy weighted spectra with steel shielding and the dynamic movements of the 137Cs and 60Co sources. The results showed that the peak locations of each source could be identified under shielded or dynamic motion conditions, each within a maximum difference of 0.08 MeV. FTY-720 S1P Receptor modulator Polyaniline/SiO2 composite was successfully prepared via in situ polymerization using polyvinyl alcohol as a surfactant. The prepared PAn/SiO2 composite was used for the removal of Zr(IV), U(VI), and Mo(VI) ions from their liquid solutions. PAn/SiO2 composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The synthesized composite was irradiated with γ-radiation from a Co-60 radioactive source with absorbed dose 50, 100, and 150 kGy and the corresponding changes in structural properties of the composites were studied. The thermal and radiation stabilities of PAn/SiO2 composite in terms of saturation capacities were studied. PAn/SiO2 composite has a good thermal stability as it retained about 78.83% of its saturation capacity upon heating at 400±1 °C, while the saturation capacity of PAn/SiO2 composite was increased from 191.28 to 319.16 mg/g for Zr(IV) with varying the irradiated doses from 0 to 150 kGy. link2 The sorption studies for several metal ions revealed marked selectivity of PAn/SiO2 composite towards Zr(IV), U(VI), and Mo(VI) ions with selectivity order; Zr(IV) > U(VI) > Mo(VI). The results indicated that PAn/SiO2 composite removed 95.33, 75.97, and 52.87% from Zr(IV), U(VI), and Mo(VI) ions, respectively at pH 3.26. Hence, analytical utility of PAn/SiO2 composite was accomplished by performing some quantitative separation such as separation of U(VI) ions from monazite leachate and separation of Zr(IV), U(VI), and Mo(VI) ions from simulated liquid waste. Thermodynamic parameter studies concluded that the adsorption of Zr(IV), U(VI), and Mo(VI) ions was spontaneous and endothermic in nature. A nuclear barcode has been proposed to identify taggants added to explosives, which encodes identifying information by adding a unique combination of taggant elements at different concentration levels. Testing was conducted on two single element solutions at three concentrations to determine minimum detection concentration levels. The effect of delaying the time to obtain measurements and its effect on uncertainty over approximately four half-lives (5 days) was tested on five 1 part per million holmium solutions. Scintillators form the chief device for radiation detection, and the study of their characteristics and their related theories is very significant. Specifically, the nonlinear behavior of scintillators under high excitation density has been closely studied owing to its direct influence on the measurements of radiation. We propose a new method to calibrate the nonlinearity of scintillators based on the electron pulse generated by a linear electron accelerator. The nonlinear light yield of several commonly used scintillators versus fluence of 70 MeV electrons in a 10 ps pulse has been measured by adjusting the charge of electron pulses, and the deposition energy threshold is also simulated and calculated. The results show that the deposition energy threshold for the occurrence of 5% nonlinearity is highest for two types of oxide scintillators, viz. LSO and PbWO4, followed by fluoride scintillators, viz. BaF2 and CeF3, and the threshold for a plastic scintillator EJ232 is lowest. The 106Ru/106Rh COB-type plaque has a cut-out section that makes it suitable to be used in eye brachytherapy to treat tumours close to the optical nerve. Nevertheless, this asymmetry makes measurements and calculations of dose rates around this kind of beta applicator more difficult to perform. In this work we present a analytical and numerical method to evaluate the relative dose rates along the central axis of the COB-type plaque and a comparison is made with a result found in literature obtained by means of Monte Carlo simulation. Auger electron therapy is an attractive modality for targeting microscopic tumors. Rhodium-103 m (103mRh, T½ = 56.1 min) is a promising Auger electron emitter that can be obtained as the decay product of palladium-103 (103Pd, T½ = 16.99 days). 103Pd was chelated in a lipophilic derivative of the 16aneS4 macrocycle and the complex was trapped on a C18 cartridge. Elution with dilute hydrochloric acid gave radiochemically pure 103mRh. We hypothesize this to be through a combination of the Szilard-Chalmers effect and transient ionization. Radiotracer investigations were carried out for tracing primary coolant in a delay tank of a swimming pool type nuclear reactor. The delay tank was designed to provide a certain delay or residence time to the primary coolant so that the short-lived radioisotopes such as (nitrogen-16 and oxygen-19) decay to a safer level before exiting from the delay tank. However, soon after commissioning of the reactor, the radiation levels at the exit of the reactor core and delay tank, in the working area were found to be higher than the permissible levels. Therefore, the main objectives of the investigations were to measure breakthrough and residence times and, to investigate flow dynamics of the coolant within the tank. Residence time distributions (RTDs) of the coolant were measured in the delay tank using technetium-99m as sodium pertechnatate as a radiotracer. link3 The breakthrough time (BTT) and mean residence time (MRT) were determined from the measured RTD and the same were found to be inadequate to allow the decay of short-lived radioisotopes to the permissible levels. Axial dispersion model with two parallel flow streams was used to simulate the measured RTD curves. Results of the model simulation indicated bypassing of the coolant. Based on the results of the radiotracer investigations, necessary modifications were carried out in the design of the tank. After implementing the modifications, the radiotracer experiments were repeated and, the BTT and the MRT were found to increase sufficient enough to allow decay of the produced radioisotopes and thus to reduce the radiation levels at the exit of the delay tank and in the working area to the safer and permissible levels. Gamma radiation of diclofop methyl (DM) an herbicide deriving from aryloxy-propionic acid was investigated. DM aqueous solutions was irradiated at different doses from 1 kGy to 8 kGy. The effects of radiation doses on UV-visible spectroscopy, pH, total inorganic carbon (TOC) and kinetic study have been studied. It was found that absorption bands decrease with increasing radiation dose. The TOC removal efficiency was 97% at 8 kGy. Several degradation by-products such as 4-(2,4-dichlorophenoxy) phenol, 2-hydroxy-propanoic acid methyl ester, 2,4-dichlorophenol, 1,4-hydroquinone, quinone, 2-chloro-1,4-hydroquinone and 1,2,4-benzenetriol were identified by gas chromatography-mass spectrometry (GC/MS) evidencing that radiation process starting with the fragmentation of the molecule involving the hydroxyl radical, which is generated by the radiolysis of water. Based on the identification intermediates, a plausible DM mineralization pathway has been proposed. Finally, a kinetic study was effected and showed that the DM degradation process is a pseudo-first order. A low background gamma-ray spectrometer was established in a ground-based laboratory. It consists of a large well (diameter 28 mm, depth 40 mm) HPGe detector and an anti-cosmic shielding system. The photon background of the present system was measured with and without the anti-cosmic mode, and compared with each other, and the detection capability with the detection efficiency calibration was estimated. The background with passive and active shields for the energy region between 40 keV and 3000 keV was reduced by 78% compared to one with just passive shield. The full energy peak efficiency for cylindrical samples with three different heights and the minimum detectable activity of the present system were tabulated for main radionuclides to be measured in environmental monitoring. New emanation sources for Rn-222 have been developed by electrodeposition of Ra-226 onto stainless-steel discs. With a high resolution of up to 20 keV FWHM in the Ra-226 peak at 4.87 MeV, defined solid-angle alpha-particle spectrometry is the method of choice to determine the deposited Ra-226 activity. The amount of emanating Rn-222 is determined by gamma-ray spectrometry using HPGe-detectors. The measurement is based on the distorted equilibrium of the Ra-226 decay chain due to Rn-222 emanation. Comparative gamma-ray spectrometric measurements with sealed, Rn-222 tight sources of the same type and geometry make the knowledge of emission probabilities and detection efficiency unnecessary. The new emanation sources allow the production of stable reference atmospheres in the regime below 300 Bq⋅m-3 with uncertainties not exceeding 2% for k = 1. Aerial gamma-ray spectrometry technique is used herein as an indirect approach for petroleum prospecting to investigate possible hydrocarbon stratigraphic and structural traps of Area-3, Northern Palmyrides, Syria. This indirect approach is based on the thorium Th normalization technique, oriented towards suppressing the influence of the regional geological signatures. The use of the thorium normalization technique in the study Area-3 allows to detect new subtle micro-seepage anomalous patterns. The detected micro-seepage occurrences are characterized by both low residual potassium values termed as KD (%) and high uranium residual values in relation to potassium, termed as DRAD (%) values. DRAD (%) results from the subtraction of potassium from uranium residual values. Eight probable zones are identified and mapped over the study area grace to the application of the thorium normalization technique, that might indicate a prospective possibility for feasible subsurface hydrocarbon accumulations and oil-bearing pay zones at Area-3.