Niveaux du 10B excités dans la diffusion élastique 9Be + p à 2 ≤ Ep ≤ 5 MeV

Absolute differential cross sections of the 9Be + p elastic scattering have been measured between 2 and 3.8 MeV proton laboratory energy. Excitation curves at five angles between θcm = 65° and 160° and angular distributions at Ep = 2.31, 2.44, 2.56, 2.62 and 2.73 MeV for θ cm = 40° to 140° have been obtained. These results together with the previous measurements at Ep ≤ 5 MeV have been compared with the calculations performed in the R-matrix formalism. A good fit has been achieved by introducing nine 10B levels at the excitation energies Ex = 8.45, 8.66, 8.78, 8.880, 8.892, 8.93, 10.00, 10.36 and 10.83 MeV. Resonance parameters for these levels have been deduced and compared with the existing values and, in some cases, with those of the analogous states in 10Be.Les sections efficaces différentielles absolues de la diffusion 9 Be + p ont été mesurées à 2 ≤ Ep < 3,8 MeV. Cinq courbes d'excitation à des angles 65° ≤ θcm ≤ 160° et cinq distributions angulaires à Ep = 2,31; 2,44; 2,56; 2,62 et 2,73 MeV et pour des angles 40° ≤ θcm ≤ 140° ont été obtenues. L'analyse simultanée de ces résultats et de données existant à Ep ≤ 5 MeV a été effectuée dans le formalisme de la matrice R. L'ensemble des données a été ajusté de façon satisfaisante en tenant compte, dans cette gamme d'énergie, de neuf niveaux du 10B situés respectivement aux énergies d'excitation Ex = 8,45; 8,66; 8,78; 8,880; 8,892; 8,93; 10,00; 10,36 et 10,83 MeV. Les paramètres associés à ces niveaux ont été déduits et comparés aux résultats de travaux antérieurs et, dans certains cas, aux paramètres des niveaux analogues isobariques du 10Be

Les résonances dans les collisions atomiques. II. Structures résonnantes et perturbations dans les collisions élastiques ions-atomes

In this part, the resonances in ion impact elastic differential cross-section are reviewed. The theory is developed from the perturbed stationary state approximation (P.S.S.). It gives an approximate expression of the charge transfer probability as a function of the scattering angle and explains the oscillations in the elastic differential cross-section. Furthermore, the "Rainbow Infect" is developed. In the last theoretical part, other perturbations in cross-section, caused by indiscernability or by coupling of states are studied. We describe devices used by several workers to measure elastic differential cross-sections or charge-transfer probabilities, and their results are reviewed.Dans cette seconde partie, notre étude porte sur les collisions élastiques par impact ionique. Leur aspect théorique est développé à partir de l'approximation dite de « l'état stationnaire perturbé » (P.S.S.). On obtient ainsi une expression approchée de la probabilité d'échange de charge en fonction de l'angle, qui explique le caractère oscillatoire de la section efficace différentielle élastique. D'autre part, on met en évidence l'existence de l'effet « Arc-en-ciel ». Enfin, on étudie d'autres anomalies de la section efficace différentielle élastique, en particulier celles liées à l'indiscernabilité des particules, ou celles dues à une perturbation induite par couplages d'états. Nous décrivons rapidement les dispositifs utilisés par différents expérimentateurs pour mesurer soit la section efficace différentielle élastique, soit la probabilité d'échange de charge, et nous terminons par un résumé des principaux résultats obtenus jusqu'à présent

Fast neutron spectrometry using thick threshold detectors

This paper discusses the use of thick threshold activation detectors for the characterization of low intensity neutron fields. This technique has been applied to the determination of the spectral emission of a low activity (37 GBq) Am-Be source. The reaction rates induced by the neutrons emitted by this source in different thick metallic targets (Al, Si, Fe, In) have been measured in the following reactions: 27Al(n,p)27Mg, 27Al(n,α)24Na, 28Si(n,p)28Al, 56Fe(n,p)56Mn, 115In(n, n′)115mIn and 115In(n, γ)116mIn. Each measured reaction rate corresponding to a threshold detector response depends on the spectral emission of the source via a correcting factor. This factor, which takes into account the source detector geometry, the neutron attenuation and diffusion by the detectors, has been determined by Monte Carlo simulation using MCNP5 code. The spectral emission of the neutron source has been generated from the response matrix of the threshold detectors by using different neutron spectrum unfolding methods (Stayn'l, Gravel and Maxed). A fairly good agreement with the assumed ISO spectrum has been achieved

Impact of the functionalized tetrazole ring on the electrochemical behavior and biological activities of novel nickel (II) complexes with a series of tetrazole derivatives

International audienceSix new nickel (II) complexes with a series of tetrazole derivatives functionalized by different substituents {5-(2-(1-Benzyltetrazol-5-yl) phenyl)-2-ethyl-4-methylthiazole (L1), 1-Benzyl-5-(2-(1-methylpyrrol-2-yl)phenyl) tetrazole (L2), 5-(2-(1-Pivalyltetrazol-5-yl)phenyl)-2-ethyl-4-methylthiazole (L3), 5-(2-(1-Methylpyrrol-2-yl) phenyl)-1-pivalyltetrazole (L4), 2-Ethyl-4-methyl-5-(2-(1 methyltetrazol-5-yl) phenyl) thiazole (L5) and 1-Methyl-5-(2-(1-methylpyrrol-2-yl)phenyl) tetrazole (L6)} have been synthesized and characterized by analytical and spectral methods. The data clearly indicated that the nickel (II) complexes are coordinated to the monodentate tetrazole derivatives via nitrogen (N3) atom of the tetrazole ring. The octahedral geometry is observed for all the complexes. The thermogravimetric analysis revealed the presence of coordinated and hydrated water molecules in the coordination sphere. The DFT calculations performed on both the ligands and the complexes allowed to optimize the structures, the stability and to explain the electrochemical behavior and the biological activities of the nickel (II) complexes. The study of the substituents effects on the redox properties of the ligands and their nickel (II) complexes were discussed via cyclic voltammograms. Electron donating substituents shift the reduction potentials toward negative values, while anodic shift of the oxidation potentials is manifested by the substituents having an electron withdrawing effect. The in vitro antimicrobial activities of the ligands and their corresponding nickel (II) complexes have been evaluated against four bacterial and two fungal strains. L1–L6 ligands and their nickel (II) complexes showed a better activity against Gram-positive bacteria. The reactivity of the complexes against Streptococcus group D varied from very sensitive to extremely sensitive activity. No activity has been recorded for the six ligands against the tested fungal strains but their complexes showed extremely sensitive antifungal activity against these strains. The electron donating effect of the substituents was found to weaken the antimicrobial activity of the complexes. The antioxidant activity of the compounds has been evaluated using the DPPH method. The results indicated that the ligands and their nickel (II) complexes exhibited a better activity against the radical DPPH in comparison to the used reference. Electron withdrawing effect of the substituents on the ligands enhanced the antioxidant activity of the ligands and their complexes

Fast neutron spectrometry using thick threshold detectors

This paper discusses the use of thick threshold activation detectors for the characterization of low intensity neutron fields. This technique has been applied to the determination of the spectral emission of a low activity (37 GBq) Am-Be source. The reaction rates induced by the neutrons emitted by this source in different thick metallic targets (Al, Si, Fe, In) have been measured in the following reactions: 27Al(n,p)27Mg, 27Al(n,α)24Na, 28Si(n,p)28Al, 56Fe(n,p)56Mn, 115In(n, n′)115mIn and 115In(n, γ)116mIn. Each measured reaction rate corresponding to a threshold detector response depends on the spectral emission of the source via a correcting factor. This factor, which takes into account the source detector geometry, the neutron attenuation and diffusion by the detectors, has been determined by Monte Carlo simulation using MCNP5 code. The spectral emission of the neutron source has been generated from the response matrix of the threshold detectors by using different neutron spectrum unfolding methods (Stayn'l, Gravel and Maxed). A fairly good agreement with the assumed ISO spectrum has been achieved

MECANISME DE LA REACTION 14N(3He, p)16O A E3He = 3 MeV

Les sections efficaces différentielles des réactions 14N(3He, p)16O ont été mesurées à E3He = 3 MeV. Les distributions angulaires de la plupart des groupes de protons de cette réaction montrent une allure caractéristique de processus d'interaction directe et ont été analysées en termes de la théorie élémentaire de l'onde plane en supposant la capture d'un deuton. La possibilité d'autres types de mécanisme direct de réaction (diagrammes rectangulaires) a été envisagée pour certains groupes.Differential cross-section measurements were made for the 14N(3He, p)16O reaction at a bombarding energy of 3 MeV. Angular distributions of some proton groups suggesting a direct process have been analysed with the PWBA theory assuming a deuteron capture. The possible manifestation of the four-point graphs is discussed