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Electron-Impact Ionization (EII) is considered one of the most important ionization methods in dynamic systems, in which elements and ions are suddenly exposed to energetic electrons. In many plasma types, it has been observed that some electrons (hot) are governed by a non-Maxwellian energy distribution. This study illustrates the effects of a non-Maxwellian distribution on beryllium and Be+2 emission lines and their effective ionization rate coefficients. The focus on beryllium as an impacted material by electron flux aimed to evaluate the EII rates for Be and generate the corresponding datasets needed for Be+2 data analysis. An interaction cross-section was generated using the Flexible Atomic Code (FAC) and used in the estimation of the EII distribution energy functions to estimate the ionization rates for a non-Maxwellian distribution. The use of non-Maxwellian energy distributions for different fractions of hot electrons showed the sensitivity of these rates to the fraction of hot electrons and the forms of the electron energy distribution. The results were in good agreement with those found in the literature.

Free-breathing external beam radiotherapy remains challenging due to the complex elastic or irregular motion of abdominal organs, as imaging moving organs leads to the creation of motion blurring artifacts. In this paper, we propose a radial-based MRI reconstruction method from 3D free-breathing abdominal data using spatio-temporal geodesic trajectories, to quantify motion during radiotherapy. The prospective study was approved by the institutional review board and consent was obtained from all participants. A total of 25 healthy volunteers, 12 women and 13 men (38 years ± 12 [standard deviation]), and 11 liver cancer patients underwent imaging using a 3.0 T clinical MRI system. The radial acquisition based on golden-angle sparse sampling was performed using a 3D stack-of-stars gradient-echo sequence and reconstructed using a discretized piecewise spatio-temporal trajectory defined in a low-dimensional embedding, which tracks the inhale and exhale phases, allowing the separation between distinct motion phases. Liver displacement between phases as measured with the proposed radial approach based on the deformation vector fields was compared to a navigator-based approach. Images reconstructed with the proposed technique with 20 motion states and registered with the multiscale B-spline approach received on average the highest Likert scores for the overall image quality and visual SNR score 3.2 ± 0.3 (mean ± standard deviation), with liver displacement errors varying between 0.1 and 2.0 mm (mean 0.8 ± 0.6 mm). When compared to navigator-based approaches, the proposed method yields similar deformation vector field magnitudes and angle distributions, and with improved reconstruction accuracy based on mean squared errors. Schematic illustration of the proposed 4D-MRI reconstruction method based on radial golden-angle acquisitions and a respiration motion model from a manifold embedding used for motion tracking. First, data is extracted from the center of k-space using golden-angle sampling, which is then mapped onto a low-dimensional embedding, describing the relationship between neighboring samples in the breathing cycle. The trained model is then used to extract the respiratory motion signal for slice re-ordering. The process then improves the image quality through deformable image registration. Using a reference volume, the deformation vector field (DVF) of sequential motion states are extracted, followed by deformable registrations. The output is a 4DMRI which allows to visualize and quantify motion during free-breathing.

This paper presents all stages of the gravimetric network of the upper Chelif basin, including its development and data processing. This network consists of twenty six gravimetric stations. The descriptions of the design ; the gravity survey of the network and the gravimetric stations coordinates are given. These gravimetric stations are connected to the Algerian zero order gravimetric network by means of relative gravimetric values. The measurements were performed using a terrestrial LaCoste Romberg D220 gravimeter, with an instrumental accuracy of 1¸tglas. The accuracy of the determination of gravity values at individual stations is about 13 ¸tgals. In order to ensure the uniformity of obtained results and thus avoid having several gravity values at the same station, the network has been compensated. This compensation was performed by the ginning method.

By measuring changes in radioelement concentrations, gamma-ray spectrometry is increasingly emerging as an efficient geophysical method that allows such changes to be geologically mapped according to lithology and soil type. At Maâdna crater in southern Algeria, this method has been used to monitor any changes in the composition of the target rocks that may be associated with the impact cratering process. For this purpose, several measurements were carried out in situ using a portable field gamma spectrometer. As a result, most predominantly calcareous surface lithologies, exposed on the rim and flanks of the crater, showed a very low emitted radiometric response over the three channels (K, Th, U). However, no more than 90 Cps were counted both inside and outside the crater. Such a rate is indeed expected in sedimentary rocks with low clay content, and this remains valid, as long as other exogenous mineralogical enrichments are excluded. On the other hand, the contoured radioelement concentrations maps, have demonstrated an anomalous enhanced gamma radiation levels of potassium-dominated peaks over the central part of the crater and in the surrounding wadis. Nevertheless, the central potassium anomaly is well correlated with the shallower magnetic one that has been described in previous studies (see e.g. Lamali et al., 2016). Therefore, either near the surrounding wadis or in the central part of this crater, this anomalously high level of radioactivity may be linked to an accumulation of later altered deposits. Consequently, there are no objective criteria to link these results to an impact event occurring at the Maâdna structure, similar to what was done at the Serra da Cangalha crater (Vasconcelos et al., 2012).

Geophysics continues to play a critical role in the future discovery of terrestrial impact structures. While the signatures within these structures may not be unique, the application of geophysics can effectively characterize them, even when they are deeply eroded or completely buried underground. In the case of Maâdna crater (33°19' N, 4°19' E), among new performed geophysical surveys, a GPR technique has been especially used to explore a supposed ejecta layer. However, GPR survey results allowed the confirmation of nonexistence of such as melting materials at Maâdna crater. Nevertheless, our different scans were interpretative against the structural context of the Maâdna structure. Indeed, most of the analyzed profiles allowed us recognizing the typical deformation effects at this structure, which can also generally be encountered at any crater-like structured site. Consequently, in view to this new resulting GPR data, even we do not definitely reject an impact origin, we are still pleading for other caratering scenarios for this structure.

In the present work, the classical Bethe–Weizsacker (BW) mass formula with five energy terms is revisited and updated. We use the least-squares adjustments on the binding energy of 2497 different nuclides from the last update of the atomic mass evaluation, AME2016 published in March 2017, to provide a new set of energy coefficients of the mass formula. The obtained set of formula coefficients allowed us to reproduce most of the experimental values of the binding energies for each nucleus with $$A \ge 50$$. The comparison between the binding energies provided with updated mass formula and those of AME2016 on the one hand, and those of previous works, on the other hand, yields relative errors that oscillate between less than $$0.05\%$$ and $$1.5\%$$. The revisited BW formula is in very good agreement with the experimental data.

Located in the North of Algeria, between two important seismogenic basins (the Cheliff and the Mitidja basin), the Khemis Miliana plain represents an important structure in understanding the connection between these two seismogenic basins. This Neogenic plain is known as a large depression covered with Quaternary alluvial deposits. It corresponds to an elongated East-West structure, is about 80 km long and 35 km wide. From September 2016 to April 2018 we achieved a new geophysical survey in this area. A total of 1536 gravity measurements points, spaced ~1 km apart were realized. This work leads to the establishment of a new structural image of the Khemis Miliana plain, using of different processing methods applied on gravity data. This allows the identification of the anomalies, causative structures and lineaments and the understanding of the connection between the Cheliff and Mitidja basins.

The Maâdna structure (Talemzane, Algeria) is located approximately 400 km south of Algiers and is formed within Upper-Cretaceous to Eocene limestones from the Saharan Platform. It is a bowl-shaped crater roughly 1.7 km in diameter. The present-day crater rim is 60 m higher than the bottom of the depression, and is raised slightly compared to the surrounding terrain. So far, several aspects of Maâdna structure cratering process remain poorly known. Recent study, geological and geophysical investigation, do not support an impact origin for this structure but suggest an alternative dissolved diapir with inverted relief. At present, geophysical studies revealed many interesting features of known terrestrial impact craters. In particular, observed signatures yielded useful information on the impact-induced physical changes in targeted rocks. These observations motivated our investigation of Maâdna crater, which uses several different geophysical surveys with particular emphasis on the GPR technique. This later is used as a valuable tool for near surface explorations. Although GPR technique has a limited use in case of impact structures, it is used in this study to discriminate between electromagnetic signatures of supposed ejectas, which were widely used to describe Maâdna structure origin. Typical GPR antennas were used to test a survey protocol in several situations during the GPR field deployment stage. In order to characterize the target thin and shallower layer, most of the common profiles were acquired using a 500 MHz shielded antenna. Otherwise, to ensure maximum waves penetration depths, “NS & EW” profiles were also acquired using a lowest frequency 30 MHz unshielded rough terrain antenna (RTA) system with a flexible “snake-like” design. Moreover, the ensued GPR characterization is then used to constrain occurred cratering process. Our GPR survey results helped us to improve our knowledge of the structure subsurface features expression. A suitable post-acquisition processing and analyses of the collected data lead us to reject the existence of any electromagnetic signature that may be attributed to the presence of any atypical materials, such as melted iron-rich material or those with distinctive physico-chemical properties, which induces electromagnetic signal modification or dissipation. Besides, our different scans could help truthful geological interpretation linked to Maâdna structure. For example, scans operated on the prevailing structural unit surrounding the Maâdna crater show clearly the most documented structural features at this crater, such as bedrocks fracturation, locally collapses, overturned and/or vertical movement of strata, etc. Specifically, the topographically corrected scans are presently interpretative against the alternative scenario of the cratering process at Maâdna, since our various analyses do not support any meteoritic evidence. As a result, valuable insights into the hypothetic diapiric piercement have been then gained from this analysis. This leads us to conclude that GPR data can be used to build another strong argument in favor of the diapiric origin at Maâdna crater.

Oral; International audience; Toutes les méthodes d’aimantation des supraconducteurs sont basées sur la variation du champ magnétique appliqué qui résulte des caractéristiques de l’inducteur utilisé. Dans ce papier nous avons développé un modèle analytique pour montrer l’effet de la présence d’une pastille supraconductrice sur la valeur de l’inductance d’une bobine circulaire de section transversale rectangulaire placée dans un circuit ferromagnétique avec entrefer. Ce modèle est basé sur la détermination du potentiel vecteur magnétique à partir de la résolution les équations de Laplace et de poisson dans les différentes régions d’intérêt en utilisant la méthode de séparation des variables. Cette résolution analytique s’effectue à l’aide d’un code de calcul développé sous MATLAB. Les résultats obtenus sont comparés avec ceux obtenus par une simulation numérique basée sur la méthode des éléments finis implémentée sous COMSOL. Une concordance remarquable est observée entre les deux résultats.

Poster; National audience; L’aimantation des supraconducteurs, notamment par des champs magnétiques impulsionnels, nécessite le dimensionnement correct de l’inducteur. Dans cet article, nous avons développé un modèle analytique dans le but de calculer l’inductance d’une bobine dans un circuit ferromagnétique avec entrefer contenant une pastille supraconductrice. Dans ce modèle, il s’agit de résoudre les équations de Laplace et de Poisson dans différentes régions d’intérêt à travers le potentiel vecteur magnétique. La résolution analytique s’effectue à l’aide d’un code de calcul développé sous MATLAB. Une simulation numérique sous COMSOL est également effectuée pour ce problème. Les deux méthodes sont comparées et les résultats coïncident parfaitement. L’expression analytique de l’inductance obtenue peut ainsi servir à dimensionner l’inducteur du système d’aimantation pour les supraconducteurs.

The authors would like to thank Thierry Lubin and Alexandre Colle for their useful discussions on this topic.; International audience; The development of bulk magnets based on REBCO type superconductors that can generate up to 17 T requires the implementation of a magnetization system, sometimes pulsed. Therefore, at least one coil around the High Temperature Superconducting (HTS) bulk is required. In this paper, we suggest an analytical approach in order to assess the magnetic vector potential and to compute the inductance of a coil having a rectangular cross-section and concentric with a magnetic circuit including an air-gap. On a proposed geometry, analytical results are compared with those obtained by using Finite Element Analysis (FEA). The gained analytical expressions give accurate results with an error less than 1% on the inductance value of the coil. The induced current density and trapped magnetic field in a HTS bulk during a Pulsed Field Magnetization (PFM) are also calculated using the proposed analytical expressions of the magnetic vector potential combined with an integral method. The achieved results show a remarkable match with those obtained with COMSOL.

International audience; This study consists in presenting an experimental study of an axial superconducting rotating machine. The inductor of the machine is based on the principle of magnetic concentration using bulks superconductors. The parameters of the machine are identified experimentally by carrying out static, dynamic, at the ambient temperature and at 77 K.

Poster; International audience; The development of cryo-magnets made with REBaCuO superconductors allows us to consider the generation of very intense magnetic field (up to 17 Tesla). This can be done with a pulsed magnetization system including one coil in the simplest case. Usually, sophisticated and complicated numerical modeling is needed to calculate electromagnetic characteristics of the inductor. Such modeling can be done, for example, using a Finite Element Analysis software to achieve a complex problem with the risk to need a readjustment of used parameters each time that we feel the numerical results are not satisfactory. For more flexibility, and in particular in the design stage, an analytical approach is proposed in the present paper with some assumptions, to calculate the magnetic vector potential components and deduce the magnetic field and inductance of the coil. This is done by the resolution of Laplace’s and Poisson’s equations in each region of interest, under Dirichlet and Newman conditions. The set of solutions is obtained with Fourier analysis and the magnetic field's expressions are given by special functions like Bessel and Legendre ones. Obtained results for the same proposed system is modeled and simulated with COMSOL Multiphysics, by the use of finite elements. Both approaches are compared and discussed.