Search results for "electron beam"
showing 10 items of 129 documents
The role of impurities in the irradiation induced densification of amorphous SiO(2).
2011
In a recent work (Buscarino et al 2009 Phys. Rev. B 80 094202), by studying the properties of the (29)Si hyperfine structure of the E'(γ) point defect, we have proposed a model able to describe quantitatively the densification process taking place upon electron irradiation in amorphous SiO(2) (a-SiO(2)). In particular, we have shown that it proceeds heterogeneously, through the nucleation of confined densified regions statistically dispersed into the whole volume of the material. In the present experimental investigation, by using a similar approach on a wider set of materials, we explore how this process is influenced by impurities, such as OH and Cl, typically involved in relevant concent…
Induced attenuation in Ce3+ and Nd3+ doped fibers irradiated with electron beams under low dose regime
2005
Abstract In this paper, we study the feasibility of rare earth doped optical fibers as dosimeters based on the attenuation induced by electron beams under standard conditions in radiotherapy. Neodymium and cerium doped fibers have been irradiated with 10 MeV electrons, the radiation-induced loss and the dynamic response have been measured in the wavelength range 1200–1600 nm. The sensitivity of the fibers is of the order of 0.1 (dB/m)/Gy and has a linear dependence on the dose.
Ion irradiation of carbon nanotubes encapsulating cobalt crystals
2008
Abstract The response of multi-walled carbon nanotubes encapsulating Co nanorods to ion irradiation was studied. The irradiation experiments with medium ion energies (40–500 keV) were carried out at high temperatures and combined with transmission electron microscopy and Raman characterization of the irradiated samples. Contrary to electron irradiation and high-energy (100 MeV) ion irradiation, we did not see accumulation of pressure inside irradiated nanotubes. We found that nanotubes with Co nanorods inside were transformed to amorphous carbon rods encapsulating Co clusters with typical diameters of 3–6 nm. As Co is magnetic, such one-dimensional composite systems could be used for variou…
Structural, Optical, and Dielectric Investigations of the Relaxor PLZT 9,75/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam
2003
A comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb (1-x )La x )(Zr 0.65 Ti 0.35 ) 1-x/4 O 3 ceramics with x = 9,75 at.% has been performed for the first time. The electron beam had the following parameters: energy E = 250 keV, current density I = 1000 A/cm 2 , pulse duration τ = 300 ns, beam density -10 15 electrons/cm 2 per pulse. Infrared reflectivity spectra in the region of 100 ÷ 2000 cm -1 were obtained in virgin, irradiated by 1500 pulses and annealed up to 500°C ceramics. The reconstruction of perovskite ABO 3 structure in irradiated samples has been studied by combined use of X-ray diffraction…
<title>Structual changes of the PLZT ceramics irradiated by high-current pulsed electron beam</title>
2003
First time comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb(1-x)Lax)(Zr0.65Ti0.35)1-x/4O3 ceramics with x = 4 and 9.75 at.% have been provided. The electron beam had the following parameters: energy E = 250 keV, current density I = 1000 A/cm2, pulse duration τ = 300 ns, beam density - 1015 electrons/cm2 per pulse. Infrared reflectivity spectra in the region of 100 ÷ 2000 cm-1 were obtained in virgin, irradiated by 1500 pulses. The reconstruction of perovskite ABO3 structure in irradiated samples has been studied by complex use of X-ray and neutron scattering and IR spectroscopy techniques revealing th…
Time-resolved FDTD and experimental FTIR study of gold micropatch arrays for wavelength-selective mid-infrared optical coupling
2021
The work was partially supported by Sweden's innovation agency Vinnova (Large area CVD graphene-based sensors/IR-photodetectors 2020-00797) and EU CAMART2 project (European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No.739508). TY acknowledges European Regional Development Fund Project No. 1.1.1.2/VIAA/4/20/740.
2D photonic defect layers in 3D inverted opals on Si platforms
2006
Dielectric spheres synthesised for the fabrication of self-organized photonic crystals such as opals offer large opportunities for the design of novel nanophotonic devices. In this paper, we show a hexagonal superlattice monolayer of dielectric spheres inscribed on a 3D colloidal photonic crystal by e-beam lithography. The crystal is produced by a variation of the vertical drawing deposition method assisted by an acoustic field. The structures were chosen after simulations showed that a hexagonal super-lattice monolayer in air exhibits an even photonic band gap below the light cone if the refractive index of the spheres is higher than 1.93.
Nanomanufacturing/Nanotechnology
2017
This chapter provides comprehensive knowledge regarding the fabrication of nanoproducts and element of micro-electromechanical systems using various techniques and processes. Both well-established techniques, such as nanomachining (ultra-precision) and new trends in improving nanoprocesses taking into account AFM, laser beam machining, electron beam machining processes are overviewed. The background of nanomachining processes, including typical machining operations such as turning, milling and grinding and different construction materials (metallic and nonmetallic), is outlined. The physical mechanisms responsible for the transition from brittle to ductile regime machining are explained. Mo…
E-beam induced damage in SiO2–Ge crystalline α-quartz, comparison with silica glass
2005
Electron beam induced transformation in crystalline α-quartz doped with germanium was studied by mean of cathodoluminescence and of phase shift interferometric microscope. E-beams with low current (below 50 nA), defocused (diameter of spot about 40 μm) and with acceleration energy of 15 kV produce swelling of the irradiated volume about 100 nm above the non-irradiated surface. The luminescence of the self-trapped near germanium exciton (GeSTE) is observed mainly. No luminescence of the germanium related oxygen deficient center with bands at 290 and at 395 nm, usual for Ge-doped silica glass (GeODC), was observed. Defocused e-beam with higher current (about 200 nA), the same energy and simil…
Monte Carlo simulations of high-energy electron beams : model validation and dose calculations
2017
Komponenttisäteilytykseen valjastetusta Varian Clinac 2100 C/D -lineaarikiihdyttimestä luotiin Monte Carlo -menetelmiä hyödyntävä simulaatiomalli. Malli luotiin aineen ja säteilyn vuorovaikutuksien laskennalliseen mallintamiseen tarkoitettua Geant4 -ohjelmointityökalupakettia käyttäen. Mallin kyky ennustaa mittaustuloksia kiihdyttimen tuottamasta 20 MeV:in elektronisuihkusta todennettiin laskettuja ja mitattuja tuloksia vertailemalla, ja mallin jatkokehityksen kannalta tärkeimmät toimenpiteet määriteltiin. Lisäksi arvioitiin mallin ennustamaa absorpoitunutta annosta vesi- ja piifantomeissa, sekä laskettiin viitearvo absorpoituneen annoksen ja elektronivuon suhteelle. Lasketut annosprofiilit…