Une plateforme pour l'analyse de matériaux par faisceaux d'ions à ARRONAX : Etude de l'effet d'humidité sur les échantillons

International audienceQuantification of soil pollution with method based on X-ray detection like X-Ray Fluorescence(XRF) suffers of multiple bias (moisture, surface state) especially when it's used for insituanalysis using portable-XRF. In order to study the effect of moisture on the results of ananalysis performed using X-Ray, we have performed studies using high energy PIXE/PIGE atthe ARRONAX. Samples were made of sand of different type. High energy PIXE/PIGE allowsus to avoid bias from surface state and to focus on moisture effect. It also allows to assessthe chemical composition of the sample. Results show a different behavior for each elementpresent in volcanic sand.</p

Study of ion emission from a germanium crystal surface under impact of fast Pb ions in channeling conditions

International audienceA thin germanium crystal has been irradiated at GANIL by Pb beams of 29 MeV/A (charge state Qin = 56 and 72) and of 5.6 MeV/A (Qin = 28). The induced ion emission from the sample entrance surface was studied, impact per impact, as a function of Qin, velocity vin and energy loss DE in the crystal. The Pb ions transmitted through the crystal were analyzed in charge (Qout) and energy using the SPEG spectrometer. The emitted ionized species were detected and analyzed in mass by a Time of Flight multianode detector (LAG). Channeling was used to select peculiar DE in Ge and hence peculiar Pb ion trajectories close to the emitting surface. The experiment was performed in standard vacuum. No Ge emission was found. The dominating emitted species are H+ and hydrocarbon ions originating from the contamination layer on top of the crystal. The mean value of the number of detected species per incoming Pb ion (multiplicity) varies as (Qin/vin)^p, with p values in agreement with previous results. We have clearly observed an influence of the energy deposition DE in Ge on the emission from the top contamination layer. When selecting increasing values of DE, we observed a rather slow increase of . On the contrary, the probabilities of high multiplicity values, that are essentially connected to fragmentation after emission, strongly increase with DE

Etude de la pulvérisation ionique de surface d'un cristal de germanium sous impact d'ions lourds rapides en condition de canalisation

We have performed an experiment at GANIL with a beam of Pb72+ and Pb56+ ions at 29 MeV/u and Pb28+ at 6,5 MeV/u. We observed the sputtering of positive ions at the entrance of a thin germanium crystal as a function of the incident charge and of the energy loss of the transmitted ions. We found that the sputtering is composed mainly of ions which come from the surface impurity layers, and from the fragmentation of large species. For an energy deposition below the amorphous layer, the dependence of the multiplicity on the charge q is qn where n3. The dependence of the yields on the charge is qn, where n varies between 2 and 6 depending on the emitted species. For a particular incident charge, we observed differential effects with the energy loss in the crystal, for the multiplicities, the yields and the fragmentation probability. The intensity of these effects is almost constant for all species issued in the case of the high energy beam. At low energy, this effect varies from one species to another, and, in the average, it is stronger than at high energy. These effects are related both to the emission depth for each species and to the density of energy deposition around the ion path below the amorphous layer. By means of simulations performed for the high energy case, we found that the differential effect on the multiplicity is weaker as a function of ion energy loss at the entrance of the crystal than as a function of their energy loss in the crystal.Nous avons effectué une expérience au GANIL avec un faisceau d'ions Pb72+ et Pb56+ à 29 MeV/u et Pb28+ à 6,5 MeV/u. Nous avons observé la pulvérisation d'ions positifs à l'entrée d'un cristal de germanium mince en fonction de la charge incidente et en fonction de la perte d'énergie des ions transmis. Nous avons trouvé que la pulvérisation est essentiellement formée des ions qui viennent de la couche d'impuretés en surface et de la fragmentation des grandes espèces émises. Pour un dépôt d'énergie donné sous la couche amorphe, la dépendance de la multiplicité avec la charge q est en qn avec n3. La dépendance des rendements avec la charge est en qn, où n varie entre 2 et 6 selon l'espèce émise. Pour une charge incidente donnée, nous avons observé des effets différentiels, en fonction de la perte d'énergie dans le cristal, sur les multiplicités, sur les rendements, ainsi que sur la probabilité de la fragmentation. L'intensité de ces effets est presque constante pour l'ensemble des espèces émises dans le cas à haute énergie. A basse énergie, cet effet varie d'une espèce à une autre, et, globalement, il est plus fort qu'à haute énergie. Ces effets sont liés à la fois à la profondeur d'émission de chaque espèce, et à la densité du dépôt d'énergie autour de la trajectoire de l'ion sous la couche amorphe. A travers des simulations effectuées à haute énergie, nous avons trouvé que les effets différentiels sur la multiplicité sont moins forts en fonction de la perte d'énergie des ions à l'entrée du cristal qu'en fonction de leur perte d'énergie dans le cristal

Étude de la pulvérisation ionique de surface d'un cristal de Ge sous impact d'ions lourds rapides en condition de canalisation

Nous avons effectué une expérience au GANIL avec un faisceau d'ions Pb72+ et Pb56+ à 29 MeV/u et Pb28+ à 6,5 MeV/u. Nous avons observé la pulvérisation d'ions positifs à l'entrée d'un cristal de germanium mince en fonction de la charge incidente et en fonction de la perte d'énergie des ions transmis. Nous avons trouvé que la pulvérisation est essentiellement formée des ions qui viennent de la couche d'impuretés en surface et de la fragmentation des grandes espèces émises. Pour un dépôt d'énergie donné sous la couche amorphe, la dépendance de la multiplicité avec la charge q est en qn avec n 3. La dépendance des rendements avec la charge est en qn, où n varie entre 2 et 6 selon l'espèce émise. Pour une charge incidente donnée, nous avons observé des effets différentiels, en fonction de la perte d'énergie dans le cristal, sur les multiplicités, sur les rendements, ainsi que sur la probabilité de la fragmentation. L'intensité de ces effets est presque constante pour l'ensemble des espèces émises dans le cas à haute énergie. A basse énergie, cet effet varie d'une espèce à une autre, et, globalement, il est plus fort qu'à haute énergie. Ces effets sont liés à la fois à la profondeur d'émission de chaque espèce, et à la densité du dépôt d'énergie autour de la trajectoire de l'ion sous la couche amorphe. A travers des simulations effectuées à haute énergie, nous avons trouvé que les effets différentiels sur la multiplicité sont moins forts en fonction de la perte d'énergie des ions à l'entrée du cristal qu'en fonction de leur perte d'énergie dans le cristalWe have performed an experiment at GANIL with a beam of Pb72+ and Pb56+ ions at 29 MeV/u and Pb28+ at 6,5 MeV/u. We observed the sputtering of positive ions at the entrance of a thin germanium crystal as a function of the incident charge and of the energy loss of the transmitted ions. We found that the sputtering is composed mainly of ions which come from the surface impurity layers, and from the fragmentation of large species. For an energy deposition below the amorphous layer, the dependence of the multiplicity on the charge q is qn where n 3. The dependence of the yields on the charge is qn, where n varies between 2 and 6 depending on the emitted species. For a particular incident charge, we observed differential effects with the energy loss in the crystal, for the multiplicities, the yields and the fragmentation probability. The intensity of these effects is almost constant for all species issued in the case of the high energy beam. At low energy, this effect varies from one species to another, and, in the average, it is stronger than at high energy. These effects are related both to the emission depth for each species and to the density of energy deposition around the ion path below the amorphous layer. By means of simulations performed for the high energy case, we found that the differential effect on the multiplicity is weaker as a function of ion energy loss at the entrance of the crystal than as a function of their energy loss in the crystalLYON1-BU.Sciences (692662101) / SudocSTRASBOURG-Bib.Central Recherche (674822133) / SudocSudocFranceF

Plateforme d'irradiation autour du cyclotron C70 du GIP ARRONAX

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Mesure de masse volumique de matériaux par rayons X pour le génie civil

International audienceThis study shows the feasibility of measuring the density of a material with an X-ray generator. X-rays are detected in transmission, with a shielded and collimated scintillator. The first measurements were made with homogeneous limestone and aluminium plates. An algorithm has also been developed to determine from the detected photons, the density of the material. The density was resolved with a good accuracy (<5%). The chemical composition was also determined but with lower accuracy (10%).</p

Non-destructive analysis: PIXE with high-energy ion beam at the ARRONAX cyclotron

National audienceParticle Induced X-ray Emission (PIXE) high-energy ion beam analysis allows for non-destructive multi-element analysis. This analysis allows the identification and quantification of medium and heavy elements in the samples, with a resolution of ug/g [1., 2.]. Several studies have shown the interest of coupling this method with another using gamma ray (Particle Induced Gamma Emission - PIGE) to complete the analysis for light elements [2., 3.].In order to be able to perform the PIXE analysis, it is necessary to know lots of important information: the effective ionization section, the characteristics of the different detectors, but also the intensity of the ion beam. In this study, an analysis of the measurement of the intensity of the different detectors available was performed for different ions (protons, deuterons, alpha particles) at different energies (17 to 68 MeV) for a wide range of intensity (150 fA, 40 nA). The results made it possible to define the optimal ranges of use of each detector according to the wishes of the use in terms of energies and intensities of the ions delivered by the beam. Another part of the study was devoted to determining the characteristics of a semiconductor x-ray detector (XPIPS). Various measurements were used to define the characteristics of the detector's components (thickness of the beryllium window, the vacuum, the Si semiconductor, etc.). These results determined the detector's effectiveness using different sources: Fe-55 (5.9 keV), Cd-109 (22.1 keV) and Am-241 (59.5 keV). Finally, different measurements of effective production sections were made for different targets (Ag, Au, Cu and Ti). These results could be compared with existing data and a theoretical model [3.].1.C. Koumeir et al, A new facility for High energy PIXE at the ARRONAX Facility, Proceeding of European Conference On x-ray spectrometry 20-25 June 2010 Figueira da Foz, Coimbra, PORTUGAL.\newline2. M. Hazim, Measurements of K-shell ionization cross sections induced by high energy proton beams over a wide range of atomic number, thesis (2017).\newline3. A. Subercaze, Combined used of X and gamma ray emission induced by the interaction of light charged ions with matter at medium energy: from primary reactions mechanisms to applications, thesis (2017)

Ion beam monitoring using bremsstrahlung X-rays

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Ion beam monitoring using bremsstrahlung X-rays

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High energy ion beam monitoring: X-rays Bremsstrahlung production cross section measurements for carbon target

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