A mask for high-intensity heavy-ion beams in the MAYA active target

The use of high-intensity and/or heavy-ion beams in active targets and time-projection chambers is often limited by the strong ionization produced by the beam. Besides the difficulties associated with the saturation of the detector and electronics, beam-related signals may hide the physical events of interest or reduce the detector performance. In addition, space-charge effects may deteriorate the homogeneity of the electric drift field and distort the subsequent reconstruction of particle trajectories. In anticipation of future projects involving such conditions, a dedicated beam mask has been developed and tested in the MAYA active target. Experimental results with a 136Xe beam are presented.status: publishe

High-precision half-life measurements of the T=1/2 mirror beta decays F-17 and Cl-33

Background: Measurements of the ft values for T=1/2 mirror β+ decays offer a method to test the conserved vector current hypothesis and to determine Vud, the up-down matrix element of the Cabibbo-Kobayashi-Maskawa matrix. In most mirror decays used for these tests, uncertainties in the ft values are dominated by the uncertainties in the half-lives. Purpose: Two precision half-life measurements were performed for the T=1/2β+ emitters, 17F and 33Cl, in order to eliminate the half-life as the leading source of uncertainty in their ft values. Method: Half-lives of 17F and 33Cl were determined using β counting of implanted radioactive ion beam samples on a moving tape transport system at the Système de Production d'Ions Radioactifs Accélérés en Ligne low-energy identification station at the Grand Accélérateur National d'Ions Lourds. Results: The 17F half-life result, 64.347 (35) s, precise to ±0.05%, is a factor of 5 times more precise than the previous world average. The half-life of 33Cl was determined to be 2.5038 (22) s. The current precision of ±0.09% is nearly 2 times more precise compared to the previous world average. Conclusions: The precision achieved during the present measurements implies that the half-life no longer dominates the uncertainty of the ft values for both T=1/2 mirror decays 17F and 33Cl.status: publishe

High-precision half-life measurement for the isospin T=1/2 mirror beta(+) decay of Na-21

The half-life of the isospin T=1/2 mirror β+ decay of 21Na was measured at the GANIL-SPIRAL radioactive ion beam facility to be T1/2=22.422 (10) s, a result that is more than a factor of 5 times more precise than the previous world average, with a resulting ft value that is now two times more precise. The precision of this new result implies that the half-life is no longer the dominant source of uncertainty in the Ft value used in the calculation of Vud from mirror decays to test the conserved vector current hypothesis of the standard model. The value of Vud deduced from mirror decays using the new half-life result is now in better agreement with the Vud derived from T=1 superallowed 0+ to 0+ transitions.status: publishe

Distribution and damage associated with the onion thrips, Thrips tabaci L. (Thysanoptera: Thripidae) according to the agro-climatic zone in Burkina Faso

RESUME L’oignon est le premier légume produit au Burkina Faso. Thrips tabaci constitue son principal insecte ravageur. Ce travail avait pour objectif d’évaluer la distribution, l’incidence et la sévérité des attaques de T. tabaci sur l’oignon. L’étude a été réalisée dans trois bassins de production représentatifs de deux zones agroécologiques du Burkina Faso : la zone sahélienne caractérisée par une pluviosité moyenne annuelle inférieure à 600 mm et une température moyenne annuelle de 35 °C ; contre une pluviosité moyenne annuelle comprise entre 600 et 900 mm et une température moyenne annuelle de 33 °C pour la zone nord soudanienne Nous avons réalisé des prospections dans 45 parcelles paysannes dans les zones de production ciblées. Des plantes d’oignon ont été prélevées dans trois quadrats posés sur une des diagonales de chaque parcelle, et les thrips trouvés sur chaque plante de chaque quadrat comptés. Tous les plants à l’intérieur du quadrat ont été donc observés. La densité moyenne la plus élevée (216 ±385 thrips au m2) a été observée dans la région du Nord tandis que l’incidence moyenne la plus élevée (95,91±8,92%) a été observée dans la Boucle du Mouhoun. La plus faible sévérité (19,29±13,27%) a été enregistrée dans le Plateau central. Cette étude est un premier pas vers le développement de stratégies alternatives de lutte contre les parasites dans le cadre de systèmes de production végétale durables à l’aide de bonnes pratiques agricoles et de l’utilisation des pesticides biologiques. © 2020 International Formulae Group. All rights reserved.Production durable intégrant la recherch

A new FEBIAD-type ion source for the upgrade of SPIRAL1 at GANIL

The SPIRAL facility at GANIL is being upgraded with a new FEBIAD ion source in order to extend its production capabilities to condensable elements. The coupling of such an ion source with the present GANIL target was recently tested online at SPIRAL at nominal power (1200 W). The results are promising as the calculated yields are in the range of those extrapolated from previous measurements at lower power and sometimes higher. This experiment and its results are presented.status: publishe

First inverse-kinematics fission measurements in a gaseous active target

The fission of a variety of actinides was induced by fusion and transfer reactions between a 238U beam and 12C nuclei, in the active target MAYA. The performance of MAYA was studied, as well as its capability to reconstruct the fission-fragment trajectories. Furthermore, a full characterization of the different transfer reactions was achieved, and the populated excitation-energy distributions were investigated as a function of the kinetic energy in the entrance channel. The ratio between transfer- and fusion-induced fission cross-sections was also determined, in order to investigate the competition between both reaction types and its evolution with the incident energy. The experimental results will be discussed with a view to forthcoming radioactive-ion beam facilities, and next-generation active-target setups.status: publishe