Measurement of energy and angular distributions of secondary ions in the sputtering of gold by swift Au-n clusters: Study of emission mechanisms

Energy and angular distributions of negative ions (Au–, Au2-, Au3-, and Au5-) emitted from gold target bombarded by Au, Au4, and Au9 projectiles at 200 keV/atom were measured with a multipixel position sensitive detector. The angular distributions are symmetrical with respect to the normal to the target surface and forward peaked. They depend on the type of emitted ions, on the emission energy, and on the projectile size. More forward directed emission is observed with Au9 projectiles. The secondary ion energy distributions obtained with Au and Au4 projectiles are well reproduced by a sum of linear collision cascades and thermal spike processes. However, in the case of Au9 projectiles the energy distributions are better described by using a simple spike model with two different average temperature regimes: the first one corresponds to high emission energy occurring in the early stage of the whole process, and the second to the low energy component

Simulation of MeV/atom cluster correlations in matter

We present an efficient algorithm able to predict the trajectories of individual cluster constituents as they penetrate relatively thick amorphous targets. Our algorithm properly treats both the intracluster Coulomb repulsion and the collisions between cluster constituents and target atoms. We have compared our simulation predictions to experimental measurements of the distribution of lateral exit velocities, and demonstrated that the in-target Coulomb explosion of 2MeV/atom carbon clusters in carbon foils must be shielded with a screening length of less than 2.5 Å. We also present a simple phenomenological model for the suppression of the exit-side charge of ions in clusters which depends on the enhanced ionization potential that an electron near an ion feels due to the ion’s charged comoving neighbors. By using our simulation algorithm we have predicted the exit correlations of the cluster constituents and verified that the charge suppression model fits the observed charge suppression of ions in clusters to within the experimental uncertainties

Analyse de spectres d'énergie β+ Méthode et applications à la détermination d'énergie totale de transition β pour des noyaux identifiés par la technique de temps de vol dans la région N ≃ Z ≃ 40

Une méthode par analyse de forme de spectres de positon a été développée à Orsay pour déterminer l'énergie totale des transitions β+. Une précision inférieure à 100 keV peut être atteinte par cette méthode qui est applicable à des spectres de faibles activités. Les spectres de référence et les spectres de Qβ inconnus sont mesurés simultanément dans les mêmes conditions. Nous avons appliqué cette méthode de détermination de Qβ à quelques isotopes produits au cours des réactions 32S + 27Al et 32S + 54Fe

Mesure de l'énergie des ions lourds par la méthode des protons projetés

Un dispositif destiné à la mesure de l'énergie des faisceaux d'ions lourds de 3 à 6 MeV/ uma a été construit. Le principe de la méthode est de mesurer l'énergie des protons projetés à zéro degré par collision élastique des ions incidents avec les noyaux d'hydrogène d'une cible de formvar. L'incertitude calculée sur l'énergie ainsi mesurée pour les ions lourds est de + 0,45 %. Des mesures faites sur des faisceaux de 19F et 40Ca d'énergie bien connue, accélérés par un Tandem MP, ont montré un écart maximum de 0,3 % entre les énergies réelles et mesurées. Le dispositif permet de contrôler ou calibrer des méthodes plus lourdes de détermination de l'énergie des ions lourds : déviation magnétique, temps de vol. Il se prête particulièrement bien à la mesure des pertes d'énergie d'ions lourds dans des ralentisseurs solides

ЗАВИСИМОСТЬ СПЕКТРА ПОТРЕБЛЯЕМОЙ МОЩНОСТИ ЭЛЕКТРОДВИГАТЕЛЯ НАСОСА ОТ ФИЗИЧЕСКИХ ПАРАМЕТРОВ МЕХАНИЗМА

In article dependence of the electric motor power consumption spectrum on physical parameters of the pump is proved. It is proved transitivity of transformation of methods of vibration-acoustic diagnostics in methods energy power diagnosticsУ статті доведено залежність спектру споживаємої потужності електродвигуна насосу від фізичніх параметрів механізму. Доведено транзитивність перетворення методів віброакустичної діагностики в методи енергодіагностики

Heavy gold cluster beams production and identification

NIM ACCIt is shown that beams of very heavy gold clusters can be produced by a liquid metal ion source (LMIS). An experimental method is described for defining the LMIS source and the Wien filter parameters that must be set to extract and select large Aun clusters. This method is based on the acceleration of the clusters to high energy (MeV) and on the measurement, after their passage through a thin foil, of their number of constituents and velocity. Only an average mass over charge value is obtained for a given set of source and Wien filter parameters. These parameters can then be used to select heavy Aun cluster beams for applications at low energy (keV) in mass spectrometry

Energy loss and angular distributions of gold cluster constituents

Heavy gold cluster beams are accelerated to high energy (hundreds of keV/atom) and break up when going through a thin foil. The energy and angular distributions of the constituents are then measured and very well reproduced by a SRIM code calculation, which takes into account atomic interactions only. These distributions do not depend on the number of constituents in the cluster and are found to be the same as those of single gold atoms at the same velocity, in the studied energy range

Very large gold and silver sputtering yields induced by keV to MeV energy Aun_n clusters (n = 1-13)

CAS, BIA

A fast ILP-based Heuristic for the robust design of Body Wireless Sensor Networks

We consider the problem of optimally designing a body wireless sensor network, while taking into account the uncertainty of data generation of biosensors. Since the related min-max robustness Integer Linear Programming (ILP) problem can be difficult to solve even for state-of-the-art commercial optimization solvers, we propose an original heuristic for its solution. The heuristic combines deterministic and probabilistic variable fixing strategies, guided by the information coming from strengthened linear relaxations of the ILP robust model, and includes a very large neighborhood search for reparation and improvement of generated solutions, formulated as an ILP problem solved exactly. Computational tests on realistic instances show that our heuristic finds solutions of much higher quality than a state-of-the-art solver and than an effective benchmark heuristic.Comment: This is the authors' final version of the paper published in G. Squillero and K. Sim (Eds.): EvoApplications 2017, Part I, LNCS 10199, pp. 1-17, 2017. DOI: 10.1007/978-3-319-55849-3\_16. The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-55849-3_1

INVESTIGATION OF THE TRANSMISSION AND STOPPING OF LIGHT IONS PASSING THROUGH A PLASMA TARGET

Transmission and energy losses of 2 MeV/u Carbon and Sulphur beams passing through a plasma target, have been extensively investigated. A hydrogen plasma ignited by an electrical discharge was coupled to the Orsay Tandem beam accelerator. Fluctuations in beam transmission have been observed and attributed to a magnetic focusing effect generated during the plasma evolution. Energy loss measurements were performed on the basis of time of flight techniques and indicate an enhanced stopping power of the plasma relative to its cold matter equivalent