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Propagation Characteristics of Airy-Gaussian Beams Passing through a Misaligned Optical System with Finite Aperture

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Optics and Photonics Journal 2014年第11期4卷 325-336页

作者： Lahcen Ez-Zariy Salima Hennani hamid nebdi Abdelmajid Belafhal Laboratory of Nuclear Atomic and Molecular Physics Department of Physics Faculty of Sciences Chouaib Doukkali University El Jadida Morocco

Propagation characteristics of finite Airy-Gaussian beams through an apertured misaligned first-order ABCD optical system are studied. In this work, the generalized Huygens-Fresnel diffraction integral and the expansion of the hard aperture function into a finite sum of complex Gaussian functions are used. The propagation of Airy-Gaussian beam passing through: an unapertured misaligned optical system, an apertured aligned ABCD optical system and an unapertured aligned ABCD optical system are derived here as particular cases of the main finding. Some numerical simulations are performed in the paper.

关键词： Airy-Gaussian Beams Huygens-Fresnel Diffraction Integral Aperture Misalignment

Propagation of Modified Bessel-Gaussian Beams in a Misaligned Optical System

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Optics and Photonics Journal 2012年第4期2卷 318-325页

作者： Lahcen Ez-Zariy hamid nebdi El Hassane Bentefour Abdelmajid Belafhal Laboratoire de Physique Nucleaire Atomique et Moleculaire Departement de PhysiqueFaculte des SciencesUniversite Chouaib DoukkaliEl JadidaMorocco LigthOnKnowledge Foundation ChicagoUSA

The formalism of generalized diffraction integral for paraxial misaligned optical systems is used to investigate the propagation of the Modified Bessel-Gaussian (MBG) beam through a misaligned thin lens. The properties of the propagation of MBG beam traveling through this misaligned ABCD optical system are discussed. A special case of misaligned circular thin lens is illustrated analytically and numerically. The shape of the MBG beam at the exit of the misaligned optical system is unchanged;however the center of the beam is shifted from the propagation axis in correlated manner with the design parameters of the optical system.

关键词： Generalized Diffraction Integral Modified Bessel-Gaussian Beams Propagation Misaligned ABCD Optical Systems Circular Thin Lens

Measurement of Natural Radioactivity and Radon Exhalation Rate in Coal Ash Samples from a Thermal Power Plant

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World Journal of Nuclear Science and Technology 2016年第3期6卷 153-160页

作者： Aziz Boukhair Laila Belahbib Khadija Azkour hamid nebdi Mohammed Benjelloun Abdelmjid Nourreddine Laboratoire de Physique Nucléaire Atomique et Moléculaire Département de Physique Faculté des Sciences Université Chouaib Doukkali El Jadida Morocco Centre Régional des Métiers de l’Education et de la Formation El Jadida Morocco Ministère de l’Intérieur Secrétariat général Province d’El Jadida Morocco Groupe RaMsEs Institut Pluridisciplinaire Hubert Curien (IPHC) Université de Strasbourg Strasbourg France

Coal is the main energy source for electricity generation in the world. In Morocco, 37% of electricity generation comes from combustion coal in thermal power plants. This combustion process generates large amounts of fly and bottom ashes. In recent years, these ashes became a great topic of interest because of their different uses and especially in construction materials. In this work, we assess radiation risks due to natural radioactivity in samples of fly and bottom ashes collected from JLEC (Jorf Lasfar Energy Company) thermal power plant, and different analyses are performed through two nuclear techniques such as gamma spectrometry and alpha dosimetry based on the use of LR115 films detectors. Our analysis shows that 226Ra activities and 232Th in both ash samples are well above the permissible activity. The values of the external risk index (Hex) and internal one (Hin) for these ashes are below unity, with the exception of 1.28 in fly ash for Hin. The obtained values for the equivalent radium Raeq and annual effective doses Ėin fly and bottom ashes are 324 Bq/kg and 210 Bq/kg, and 0.18 mSv/y and 0.11 mSv/y, respectively. The surface radon exhalation rates for the samples of fly and bottom ashes are 276 mBq⋅m-2⋅h-1 and 381 mBq⋅m-2⋅h-1, respectively. Based on these results, we have shown that fly ash and bottom one from thermal power plant JLEC didn’t have, in any case, a health risk to the public so it can be effectively used in various construction activities.

关键词： Natural Radioactivity Gamma Spectrometry LR115 Fly Ash Bottom Ash Equivalent Radium Annual Effective Doses Exhalation of Radon

Assessment of the Radiological Impact on the Environment near a Storage Site of Coal Ashes in a Thermal Power Plant

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World Journal of Nuclear Science and Technology 2016年第4期6卷 206-216页

作者： Aziz Boukhair Laila Belahbib Khadija Azkour hamid nebdi Mohammed Benjelloun Abdelmjid Nourreddine Laboratoire de Physique Nucléaire Atomique et Moléculaire Département de Physique Faculté des Sciences Université Choua&#239 b Doukkali El Jadida Morocco Laboratoire de Physique Nucléaire Atomique et Moléculaire Département de Physique Faculté des Sciences Université Choua&#239 b Doukkali El Jadida Morocco Centre Régional des Métiers de l’Education et de la Formation El Jadida Morocco Ministère de l’Intérieur Secrétariat Général Province d’El Jadida Morocco Groupe RaMsEs Institut Pluridisciplinaire Hubert Curien (IPHC) Université de Strasbourg Strasbourg France

The radiological impact of coal ashes, with enhanced natural radioactivity in the storage site, is due to the presence of naturally occurring radionuclides. Some of these radionuclides have a radioactive period of several million years and will, therefore, have time to migrate to the soil, atmospheric air, surface water, and groundwater. This impact depends mainly on the activity of these coal ashes, the duration of exposure to such waste, transfers to the air, and the leaching phenomenon by rainwater. In this study, and so as to assess the radiological impact of coal ashes of the storage site of the JLEC-Morocco thermal power plant on environment, some analyses are performed by alpha dosimetry and a digital dosimeter on samples of coal ashes, soil, atmospheric air, surface water and groundwater belonging to a perimeter of 10 km around that site. The obtained results show that, within the studied area, the radiological impact on the soil of the coal ashes of the storage site is insignificant even though the concentrations of radon in the near vicinity (1 to 2 km) are moderately important, and remain below 200 Bq/m3. In the atmospheric air, this impact remains medium for the neighborhoods of the storage site (2 to 3 km) with radon activities superior to 10 Bq/m3. These results also show that there may be a water contamination of wells located at the storage site without any transfer of radioactivity into the groundwater of the area studied where the concentrations of radon are less than 11.1 Bq/l.

关键词： Storage Site Coal Ashes Environment Radiological Impact Soil Water Atmospheric Air LR115 Radon Volumetric Activity Exhalation of Radon

Propagation of Modified Bessel-Gaussian Beams in a Misaligned Optical System

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