Papers by Haifa Ben Abdelouahed
In the phosphoric acid production process, the time a particle spends inside the chemical reactor... more In the phosphoric acid production process, the time a particle spends inside the chemical reactor (residence time) is of paramount importance to process engineers. Residence time distribution (RTD) gives information on the efficiency of the chemical reactor, on the efficiency of the process, and also the availabilities of the reactive volume for the reaction (active volume vs. dead volume). Traditionally, chemical engineers used chemical tracer to determine the RTD. However, first disadvantage is that the chemical tracer could not allow an online diagnosis: the samples containing chemical tracer have to go to a lab for analysis, second disadvantage is that the chemical tracer is less sensitive than radioactive ones because of its adsorption onto strata or its retention in rocks. Consequently, chemical tracer results are not always precise and cannot convincingly explain the multiple flow-path model. Radioactive tracers are the only tracers capable of measuring the active RTD with high degree of precision and give information on the internal recirculation rate. In this work, we will describe the application of radiotracer method for RTD measurement in the phosphoric acid production process and give results and discussion of each case encountered.
We have implemented in the Geant4 simulation toolkit a set of new ionisation cross sections for t... more We have implemented in the Geant4 simulation toolkit a set of new ionisation cross sections for the simulation of particle induced X-ray emission (PIXE), based upon theoretical and semi-empirical models. The set provides a model based on the so-called ECPSSR theory for the computation of K-shell ionisation cross sections for proton and alpha particle impact. A second model is based upon semi-empirical expressions proposed by Orlic for the calculation of L i-subshells ionisation cross sections for proton impact. Our developments are compared to ionisation cross sections already existing in the Geant4 toolkit and to experimental data.
Radiotracer investigations were carried out in two identical phosphoric acid production reactors ... more Radiotracer investigations were carried out in two identical phosphoric acid production reactors and a triple super phosphate (TSP) production reactor in three different plants in Tunisia. The main objective of the study was to investigate and compare their flow behavior and identify flow abnormalities, if any. Residence time distribution (RTD) of the process material (ore pulp) was measured in the three reactors using Iodine-131. The measured RTDs were treated and analyzed to obtain flow parameters such as the mean residence time (MRT), dead volume, and extent of bypassing. The treated RTD curves were modeled using a suitable mathematical model, and the values of the parameters were obtained. The results of the investigations were used to evaluate and compare the flow performance of the reactors, quantify the degree of mixing, and visualize the prevailing flow patterns. The results of the investigations are expected to be used to make necessary modifications to enhance the efficiency and optimize the performance of the reactors or the production process.
Geant4 is a general purpose and open source C++ Monte Carlo simulation toolkit, widely used in th... more Geant4 is a general purpose and open source C++ Monte Carlo simulation toolkit, widely used in the scientific community. It is able to simulate physical interactions of particles through matter. According to the user's needs, models for the simulation of electromagnetic (EM) interactions are provided in two Geant4 subpackages, the 'standard' EM subpackage, well suited for a wide range of applications and the 'low-energy' EM subpackage, able to reach the electronVolt regime. Particle-induced X-ray emission (PIXE) is a well known and a very useful technique for quantitative elemental analysis in environmental, archaeological, biological, medical and space applications. An atomic de-excitation module is part of the Geant4 'low-energy' EM subpackage since 1999 and has been validated in recent years. PIXE simulation has been included in this subpackage in 2001 and new ionisation cross-sectional models following the ECPSSR theory have been added for the PIXE simulation in 2008. In 2010, these models have been further extended to higher energies. In this work, we present new results on the verification of these models and an overview of the new interface to PIXE modelling prepared for the recent public release of the Geant4 toolkit (December 2010) allowing a unified usage of the Geant4 de-excitation module by both 'standard' and 'low-energy' subpackages. Copyright
To determine residence time distribution (RTD) in the phosphate treatment reactor we apply radiot... more To determine residence time distribution (RTD) in the phosphate treatment reactor we apply radiotracer method. However this method becomes effective and profitable only if the radiotracer is the suitable one. The problem to resolve in our study is "which phase of the phosphate slurry our injected radiotracer is following?". For that we add radiotracer to the phosphate slurry and we proceed to phase separation using a filtration system. We follow simultaneously-using appropriate detectors-the behavior and the quantity of the radiotracer in both phases during the separation stage. The same experiment is applied twice using successively 99m Tc and 131 I radiotracers. The comparative study proves that 131 I is more suitable than 99m Tc for solid phase labeling of phosphate slurry.
Dans le cadre d'une étude concernant l'impact sur l'environnement des usines de phosphates implan... more Dans le cadre d'une étude concernant l'impact sur l'environnement des usines de phosphates implantées dans la région du golfe de Gabès dans le sud tunisien, une série de mesures préliminaires a été récemment conduite. Douze échantillons de sol ont été prélevés le long du golf de Gabès au voisinage d'une usine de traitement des minerais de phosphates. L'analyse de ces échantillons de sol par spectrométrie gamma haute résolution a révélé la présence d'une activité amma de plus de
Journal of Instrumentation
The Nuclear Science and Instrumentation Laboratory (NSIL) is currently establishing a Neutron Sci... more The Nuclear Science and Instrumentation Laboratory (NSIL) is currently establishing a Neutron Science Facility (NSF) based on two compact neutron generators: Deuterium-Deuterium (DD), resulting in 2.45 MeV neutrons, and Deuterium-Tritium (DT), resulting in 14.1 MeV neutrons, with maximum source intensities up to 5 × 106 n/s and 4 × 108 n/s over 4π, respectively. Neutron/X-ray radiography and tomography are two of the applications the NSF will be equipped with. In this paper, we report the state of the radiography and tomography system, and the neutron/X-ray radiography and tomography experiments we performed. Good radiographs and tomographs are obtained with X-ray. The spatial resolution of the X-ray radiography system is measured to be about 0.1 mm. The thermal neutron radiographs and fast neutron radiographs have proved that the DD neutron generator will be beneficial to demonstrate neutron radiography capabilities for educational purposes. Additionally, the detail of the collimat...
AIP Conference Proceedings, 2007
Abstract The efficiency of a Si (Li) detector was determined experimentally and adequately simula... more Abstract The efficiency of a Si (Li) detector was determined experimentally and adequately simulated with the GEANT4 code in the energy range from 5 to 27 keV. The point-like sources used were 55 Fe, 65 Zn, 85 Sr, 109 Cd and 241 Am. For simulation of the detector response we have used a recent version of GEANT4 8.0 (Released 10 February 2006). In this version, all needed electro-magnetic processes are considered, essentially Compton scattering, photo-electric effect, Raleigh effect, multiple scattering, fluorescence and Auger ...
Carthage punique diffusion et permanence de sa culture en Afrique antique 15 Boutheina MARAOUI TE... more Carthage punique diffusion et permanence de sa culture en Afrique antique 15 Boutheina MARAOUI TELMINI 1 , Jaloul BÉJAOUI 2 , Haïfa BEN ABDELOUAHED 3 , Salah BOUHLEL 4 CONTRIBUTION À LA CARACTÉRISATION MINÉRALOGIQUE, PÉTROGRAPHIQUE ET CHIMIQUE DE LA CÉRAMIQUE PUNIQUE COMMUNE DE CARTHAGE ET DES ARGILES DE LA RÉGION I-INTRODUCTION : (B. Maraoui Telmini) Des investigations scientifiques 5 , menées sur des échantillons de céramique punique de Carthage, permirent à P. Cintas de conclure en 1950, à « …une très grande analogie des compositions chimiques des terres entraînant une présomption d'origine commune de l'argile utilisée aux différentes époques…les différences de structure importantes révélées par les rayons X doivent être attribuées à des différences dans la technique de la cuisson» 6 . Plus récemment, des recherches archéométriques effectuées sur des échantillons de vases ouverts à engobe rouge de Carthage 7 parviennent à la distinction de deux types d'argile utilisés...
Materials Characterization, 2010
We applied the proton-induced X-ray emission (PIXE) analytical technique to twenty-eight medieval... more We applied the proton-induced X-ray emission (PIXE) analytical technique to twenty-eight medieval silver coins, selected from the Tunisian treasury. The purpose is to study the fineness evolution from the beginning of the 7th to the 15th centuries AD. Each silver coin was cleaned with a diluted acid solution and then exposed to a 3MeV proton beam from a 1.7 MV tandem accelerator. To allow the simultaneous detection of light and heavy elements, a funny aluminum filter was positioned in front of the Si (Li) detector entrance ...
X-Ray Spectrometry, 2011
Geant4 is a general purpose and open source C++ Monte Carlo simulation toolkit, widely used in th... more Geant4 is a general purpose and open source C++ Monte Carlo simulation toolkit, widely used in the scientific community. It is able to simulate physical interactions of particles through matter. According to the user's needs, models for the simulation of electromagnetic (EM) interactions are provided in two Geant4 subpackages, the 'standard' EM subpackage, well suited for a wide range of applications and the 'low-energy' EM subpackage, able to reach the electronVolt regime. Particle-induced X-ray emission (PIXE) is a well known and a very useful technique for quantitative elemental analysis in environmental, archaeological, biological, medical and space applications. An atomic de-excitation module is part of the Geant4 'low-energy' EM subpackage since 1999 and has been validated in recent years. PIXE simulation has been included in this subpackage in 2001 and new ionisation cross-sectional models following the ECPSSR theory have been added for the PIXE simulation in 2008. In 2010, these models have been further extended to higher energies. In this work, we present new results on the verification of these models and an overview of the new interface to PIXE modelling prepared for the recent public release of the Geant4 toolkit (December 2010) allowing a unified usage of the Geant4 de-excitation module by both 'standard' and 'low-energy' subpackages. Copyright
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2009
We have implemented in the Geant4 simulation toolkit a set of new ionisation cross sections for t... more We have implemented in the Geant4 simulation toolkit a set of new ionisation cross sections for the simulation of particle induced X-ray emission (PIXE), based upon theoretical and semi-empirical models. The set provides a model based on the so-called ECPSSR theory for the computation of K-shell ionisation cross sections for proton and alpha particle impact. A second model is based upon semi-empirical expressions proposed by Orlic for the calculation of L i-subshells ionisation cross sections for proton impact. Our developments are compared to ionisation cross sections already existing in the Geant4 toolkit and to experimental data.
Progress in Nuclear Science and Technology, 2011
An overview of the electromagnetic (EM) physics of the Geant4 toolkit is presented. Two sets of E... more An overview of the electromagnetic (EM) physics of the Geant4 toolkit is presented. Two sets of EM models are available: the "Standard" initially focused on high energy physics (HEP) while the "Low-energy" was developed for medical, space and other applications. The "Standard" models provide a faster computation but are less accurate for keV energies, the "Low-energy" models are more CPU time consuming. A common interface to EM physics models has been developed allowing a natural combination of ultra-relativistic, relativistic and low-energy models for the same run providing both precision and CPU performance. Due to this migration additional capabilities become available. The new developments include relativistic models for bremsstrahlung and e+e-pair production, models of multiple and single scattering, hadron/ion ionization, microdosimetry for very low energies and also improvements in existing Geant4 models. In parallel, validation suites and benchmarks have been intensively developed.
Journal of Radioanalytical and Nuclear Chemistry, 2011
ABSTRACT In the phosphoric acid production process, the time a particle spends inside the chemica... more ABSTRACT In the phosphoric acid production process, the time a particle spends inside the chemical reactor (residence time) is of paramount importance to process engineers. Residence time distribution (RTD) gives information on the efficiency of the chemical reactor, on the efficiency of the process, and also the availabilities of the reactive volume for the reaction (active volume vs. dead volume). Traditionally, chemical engineers used chemical tracer to determine the RTD. However, first disadvantage is that the chemical tracer could not allow an online diagnosis: the samples containing chemical tracer have to go to a lab for analysis, second disadvantage is that the chemical tracer is less sensitive than radioactive ones because of its adsorption onto strata or its retention in rocks. Consequently, chemical tracer results are not always precise and cannot convincingly explain the multiple flow-path model. Radioactive tracers are the only tracers capable of measuring the active RTD with high degree of precision and give information on the internal recirculation rate. In this work, we will describe the application of radiotracer method for RTD measurement in the phosphoric acid production process and give results and discussion of each case encountered.
Radioprotection, 2002
Dans le cadre d'une étude concernant l'impact sur l'environnement des usines de phosphates implan... more Dans le cadre d'une étude concernant l'impact sur l'environnement des usines de phosphates implantées dans la région du golfe de Gabès dans le sud tunisien, une série de mesures préliminaires a été récemment conduite. Douze échantillons de sol ont été prélevés le long du golf de Gabès au voisinage d'une usine de traitement des minerais de phosphates. L'analyse de ces échantillons de sol par spectrométrie gamma haute résolution a révélé la présence d'une activité amma de plus de 1 700 Bqkg due à la présence des radio-isotopes : '"Ph, "'Ra, 2'4Pb, *14Bi, et Cette activité reste pratiquement constante même a une distance de plus d'un kilomètre du site industriel que ce soit dans le milieu terrestre que dans le milieu marin. High-resolution gamma spectrometry analysis of soi1 samples collected in the vicinity of phosphate plant in the region of Gabes in South Tunisia. A set of preliminary measurements have heen conducted in order ta study the impact on the environment of the phosphates plants located in the golf of Gabes in soutb Tunisia. Twelve samples of soi1 have been collected in the vicinity of such a plant. The analyses of tbese samples have been achieved by high-resolution gamma spectrometry technique revealing a gamma activity of 1 700 Rqkg due ta the presence of the following radioisotopes: '"Pb, "'Ra, '14Pb, *14Bi, and This activity remains practically constant even more than one kilometer far from the plant. ' Facuit6 des Sciences de Monaiir. DSparrcincni dc Physique, SOU0 Mona\iir, Tunisic.
Dans le cadre d'une étude concernant l'impact sur l'environnement des usines de phosphates implan... more Dans le cadre d'une étude concernant l'impact sur l'environnement des usines de phosphates implantées dans la région du golfe de Gabès dans le sud tunisien, une série de mesures préliminaires a été récemment conduite. Douze échantillons de sol ont été prélevés le long du golf de Gabès au voisinage d'une usine de traitement des minerais de phosphates. L'analyse de ces échantillons de sol par spectrométrie gamma haute résolution a révélé la présence d'une activité amma de plus de 1 700 Bqkg due à la présence des radio-isotopes : '"Ph, "'Ra, 2'4Pb, *14Bi, et Cette activité reste pratiquement constante même a une distance de plus d'un kilomètre du site industriel que ce soit dans le milieu terrestre que dans le milieu marin. High-resolution gamma spectrometry analysis of soi1 samples collected in the vicinity of phosphate plant in the region of Gabes in South Tunisia. A set of preliminary measurements have heen conducted in order ta study the impact on the environment of the phosphates plants located in the golf of Gabes in soutb Tunisia. Twelve samples of soi1 have been collected in the vicinity of such a plant. The analyses of tbese samples have been achieved by high-resolution gamma spectrometry technique revealing a gamma activity of 1 700 Rqkg due ta the presence of the following radioisotopes: '"Pb, "'Ra, '14Pb, *14Bi, and This activity remains practically constant even more than one kilometer far from the plant. ' Facuit6 des Sciences de Monaiir. DSparrcincni dc Physique, SOU0 Mona\iir, Tunisic.
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Papers by Haifa Ben Abdelouahed