Results 1 - 10 of 27399
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[en] A general treatment of indirect recoil implantation following nuclear reactions is given for the first time. This method allows implantation into any substrate of a wide range of species produced by nuclear reactions either in a thin sacrificial target or from a solid target. It is demonstrated that this can be done whilst avoiding primary beam damage to the substrate. Two cases are considered, the general one in which non-elastic nuclear reactions produce the recoil species of interest and secondly the special case of elastic recoils. In both cases a number of novel features of the process not previously described are outlined. For example, by controlling the angular acceptance of the substrate for recoil products the method can be tailored to give well controlled implantation profiles very similar to direct implantation (i.e., approximately Gaussian in range) or more extensive depth distributions whose profiles are simply determined by the centre of mass angular distribution of the reaction product. The flux of particles available for implantation is approximately 10-4 smaller than from direct implantation facilities, but is comparable to the useful implantation dose achieved by the established technique of direct elastic recoil implantation. The radiation damage is little more than that associated with the indirect implant itself in contrast to direct elastic recoil implantation where the potential damage produced often mediates against the use of that technique. The main advantage of this relatively new method over the conventional methods is the wider range of species which can be implanted with minimum damage to the substrate. These include elements which cannot be conveniently produced from ion sources as well as exotic species which cannot be produced other than by nuclear reactions; radioactive species are good examples of both cases. (orig.)
[en] Ion implantation is now being applied successfully to the treatment of engineering tools and components in order to improve their resistance to wear, fatigue and oxidation. Examples are given to show the effectiveness of the process in steels, chromium, cemented carbides and titanium alloys. These applications have led to the development of a new range of equipment to provide the necessary high beam currents and versatile work-handling facilities. The process of bombardment-diffused coating (BDC), by which a thin metallic coating is caused to diffuse into the substrate under ion bombardment, is providing new possibilities for tailoring the surface properties of materials to meet arduous conditions. (orig.)
[en] Purpose: To evaluate performance characteristics of currently available superficial femoral artery (SFA) stents and stent delivery systems (SDS). Materials and Methods: Six 7 mm/80 mm stent systems were included: BIOTRONIK Astron Pulsar (4F), EDWARDS LifeStent Flexstar, ev3 PROTEGE Everflex, CORDIS Smart Control, BARD E-Luminexx, GUIDANT Absolute (all 6F). The SDS were evaluated for profile, flexibility in the stent region, trackability and pushability through a tortuous vessel model and release force during deployment. The stents were evaluated for flexibility, radial force during expansion and compression, and shortening. Results: The 4F system had a profile of 1.45 mm, and the 6F stent systems had a profile of 1.96 - 2.10 mm. The Astron Pulsar was most flexible (195 Nmm2) compared to 334 - 972 Nmm2 for the 6F systems. The track force of the stiffest system (Flexstar, 0.314N) was higher than that of the Astron Pulsar (0.273N) but lower than that of the other systems (0.387 - 0.579N). The release force was 1.69N (Absolute), 2.05N (Astron Pulsar) up to 13.00N (Flexstar). The radial force for a 6 mm stent diameter during expansion ranged from 3.95N (Absolute) and 3.99N (Astron Pulsar) up to 7.22N (FlexStar) but was higher when compressed. Conclusion: The 4F system had the best flexibility and trackability. The release force was high in most systems with release handles. The radial force of all tested stents covers a broad range. These results could be helpful to find the best stent for different lesions. (orig.)
[en] The invention relates to a method of ion implantation on a surface, that permits to obtain a very homogeneous implantation in surface as well as in depth. The method can be used in the fabrication of integrated circuits, and especially circuits provided with MOS transistors. According to the invention, the target is submitted, during its scanning by an ion beam along two X and Y directions, to at least one rotary motion around an axis nearly parallel to the direction of the particle beam and perpendicular to the X,Y plane. According to a mode of the invention the target is made to have a double rotary motion around two axes nearly parallel to the direction of the particle beam, the various points of the target such describing epicycloids during the implantation process. In both cases, the variations in the concentration of the implanted particles do not go beyond 1%. A slight inclination (0 deg to 15 deg) of the target (substrate) with respect to the direction of the particle beam permits channeling effects inside the crystal to be minimized
[fr]L'invention concerne un procede d'implantation ionique sur une surface qui permet une implantation tres homogene tant en surface qu'en profondeur. Le procede peut etre utilise pour la fabrication de circuits integres et tout particulierement des circuits a transistors MOS. Selon l'invention, on soumet la cible, lors de son balayage par un faisceau d'ions selon deux directions X et Y, a un mouvement de rotation au moins, autour d'un axe sensiblement parallele a la direction du faisceau de particules et perpendiculaire au plan X,Y. Un mode de realisation comsiste a soumettre la cible a un double mouvement de rotation autour de deux axes sensiblement paralleles a la direction du faisceau de particules, ce qui fait que les points de la cible decrivent une epicycloide lors de l'implantation. Dans l'un et l'autre cas, les variations de concentration des particules implantees ne depassent pas 1%. En inclinant legerement (0 a 15 deg) la cible (substrat) par rapport a la direction du faisceau de particules on peut minimiser les effets de canalisation dans le cristal
[en] The present investigation is concerned with laser annealing of P+ implanted Si. The aim of the work was to study the crystallization behavior of damage structure occurring due to high dose rate implantation using transmission electron microscopy (TEM) as the method of examination
[en] In fundamental studies of low-energy ion irradiation effects on DNA, calculation of the low-energy ion range, an important basic physical parameter, is often necessary. However, up to now a unified model and approach for range calculation is still lacking, and reported data are quite divergent and thus unreliable. Here we describe an approach for calculation of the ion range, using a simplified mean-pseudoatom model of the DNA target. Based on ion stopping theory, for the case of low-energy (≤ a few keV) ion implantation into DNA, the stopping falls in the low reduced energy regime, which gives a cube-root energy dependence of the stopping (E1/3). Calculation formulas of the ion range in DNA are obtained and presented to unify the relevant calculations. The upper limits of the ion energy as a function of the atomic number of the bombarding ion species are proposed for the low-energy case to hold. Comparison of the results of this approach with the results of some widely used computer simulation codes and with results reported by other groups indicates that the approach described here provides convincing and dependable results.
[en] The proposed work is devoted to the influence of protons with 70 keV energy using the method of ion implantation 1·1015sm-2 dose on the optical and photoelectrical properties of the GaS monocrystal. The photoconductivity rise was observed in the 490nm-900nm wavelength interval as the passage of time.In the 505 nm wavelength photosensitivity was increased to 5,3 times.The location of the maximum peak which compatible to the GaS monocrystal in the 1·1015 sm-2 dose whit 70 keV energy protons the "improvment" of the photosensitivity crystal is due to order of the regulary increase which was happened in the structure.
[en] Ion implantation is conventionally associated with the controlled modification of the physical or chemical properties of the surface of a solid target. This note describes the extension of the process to the ion beam treatment of materials in powder form. It briefly outlines the special experimental techniques which have been found to be necessary and it identifies some quite general features which distinguish the ion doping of continuous solid surfaces and discrete particles. (author)