1,721,100 research outputs found
Proton emission from resonant laser absorption and self-focusing effects from hydrogenated structures
No full textEffects of resonant absorption and self-focusing are investigated by using fast and intense laser pulses. The ion emission and acceleration in the non-equilibrium laser-generated plasma are investigated at low and high intensities, from 1010 up to about 1016 W/cm2.
The properties of plasma are strongly dependent on the time and space, laser intensity and wavelength.
A special interest concerns the energetic and intense proton generation for the multiplicity use that proton beams have in different scientific fields (Nuclear Physics, Astrophysics, Bio-Medicine, Microelecronics, etc.).
Investigations have been performed at INFN-LNS of Catania and at PALS Laboratory of Prague, by using thick and thin targets and different technique of ion analysis.
The mechanisms of resonant absorption of the laser light, produced in special targets containing nanostructures with dimensions comparable with the laser wavelength, enhances the proton energy. The mechanisms of self-focusing, obtained by changing the laser focal distance from the target surface, increase the local intensity and consequently the high directional ion acceleration.
Real-time ion detections were performed through Thomson parabola spectrometer (TPS), ion collectors (IC), SiC detectors and ion energy analyzer (IEA) employed in time-of-flight configuration (TOF).
The energy and the amount of ions increase significantly when the two non-linear phenomena occurs, as will be described
Laser fusion system and method
No full textReazione di fusione nucleare indotta da laser su target di silici
Particle size determination of silver nanoparticles generated by plasma laser ablation by means deconvolution method
No full textSilver nanoparticles were synthesized in vacuum (10−7) by using a Nd:YAG high-power pulsed laser
without any catalytic gas and/or thermal annealing processes. The ablated material was collected on
several SiO2/Si substrates (with 50 nm thickness) deposited before the laser ablation with a plasmaenhanced
chemical vapor deposition system. The substrates were analyzed with the aid of a variable angle
spectra ellipsometer at different angles. The analysis revealed the presence of a surface plasmon resonance
at about 3 eV, which is in good agreement with results in the literature.Adeconvolution method utilizing the
Lorentz model was applied to fit the experimental optical absorption peaks in order to recognize different
groups of nanoclusters with different sizes varying from 2 to 10 nm in radius. Electronic elaborations
of scanning electron microscopy of the embedded particles in the SiO2 matrix were also carried out to
measure their densities as a function of the deposition time and dimension distributions. The experimental
measurements were performed at the INFN-LNS laboratory of Catania and at the MT laboratory of the
FBK-IRST foundation of Trento
Real-Time Diagnostics of Fast Light Ion Beams Accelerated by a sub-Nanosecond Laser
No full textMulti-MeV proton and light ion beams had been produced using the 300 ps, kJ-class iodine laser, operating at Prague Asterix Laser System (PALS) Centre in Prague. The target material had been chosen in such a way so as to increase the proton beam current density (approaching 0.1 A/cm2 at the distance of 1 m from the source). The real-time ion detection was performed by means of a standard flat and ring ion collectors (IC) in the time-of-flight (TOF) configuration. The ICs had been shielded with aluminum foils of various thickness, in order to cut the long photo-peak contribution that is usually overlapping with the ultrafast particle signal, and to analyze mainly the laser-accelerated proton beam. The processing of the obtained experimental IC data is described in some detail, including the deconvolution of TOF signals, evaluation of the UV/soft-X-ray photo-peak absorption, and ion transmission calculations for different metallic filters
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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