A5102719378- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Silicon Nanostructures and Photoluminescence
- Superconducting Materials and Applications
- Silicon and Solar Cell Technologies
- nanoparticles nucleation surface interactions
- Semiconductor Quantum Structures and Devices
- Magnetic confinement fusion research
- Gold and Silver Nanoparticles Synthesis and Applications
- Semiconductor materials and interfaces
- Chalcogenide Semiconductor Thin Films
- Gyrotron and Vacuum Electronics Research
- Thin-Film Transistor Technologies
- Laser-Plasma Interactions and Diagnostics
- Spectroscopy and Quantum Chemical Studies
- Quantum Dots Synthesis And Properties
- Semiconductor materials and devices
- Molecular Junctions and Nanostructures
- Particle physics theoretical and experimental studies
- Advanced X-ray Imaging Techniques
- Material Dynamics and Properties
- 2D Materials and Applications
- Solid-state spectroscopy and crystallography
- Integrated Circuits and Semiconductor Failure Analysis
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2009-2023
Istituto Nazionale di Fisica Nucleare
2002-2023
Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
2020
AREA Science Park
2018
Elettra-Sincrotrone Trieste S.C.p.A.
2018
University of California, Los Angeles
2018
Rome International Center for Materials Science
2018
Adekunle Ajasin University
2015
University of Ibadan
2015
University of Padua
1985-2013
The electron-positron collider DAPhiNE, the Italian Phi factory, has been recently upgraded in order to implement an innovative collision scheme based on large crossing angle, small beam sizes at point, and compensation of beam-beam interaction by means sextupole pairs creating a "crab-waist" configuration region. Experimental tests novel exhibited increase factor 3 peak luminosity with respect performances reached before upgrade. In this Letter we present new scheme, discuss its advantages,...
Nonthermal generation of coherent-acoustic phonons is observed in metallic nanoparticles tin and gallium, which are solid liquid, respectively, at room temperature, by applying femtosecond pump-and-probe spectroscopy. Oscillations the photo-induced differential reflection clearly detected picosecond time domain. The measured period increases approximately linearly with size over a wide range extracted sound velocities consistent those bulk. Transition to ballistic regime carrier excitation...
The electron thermalization process both in solid and liquid metallic gallium nanoparticles with radii the range 50--90 \AA{} is investigated by femtosecond pump-probe measurements. results show that temporal behavior of energy relaxation similar phases, a time constant varying from $\ensuremath{\sim}0.6$ to $\ensuremath{\sim}1.6\mathrm{ps}$ increasing nanoparticle size. We interpret experimental data terms size-dependent electron-surface interaction model importance exchange surface phonons...
Flow visualizations and phase-averaged particle image velocimetry (PIV) measurements of a jet in crossflow configuration at very low Reynolds numbers ( Re j ≃ 100) are performed water tunnel for jet-to-cross-stream velocity ratios R ranging from 1.5 to 4.5. The PIV vector fields flow visualizations, carried out by injecting methylene blue dye the laser induced fluorescence (LIF) technique, analysed characterize effect on formation evolution large-scale vortices. It is shown that two distinct...
Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible broader scientific community. By overcoming current limits conventional pushing particles larger energies, the availability strong tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent compact...
We report on femtosecond transient reflectivity measurements performed metallic tin nanoparticles, embedded in an ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ matrix, with average radii the range 20--60 \AA{}. It was observed that time behavior of decays depends upon particle size. The results can be interpreted terms a size-dependent electron-surface interaction thermalization process and substantially size-independent electron-electron thermalization. \textcopyright{} 1996 American Physical Society.
Low-melting-point metal nanoparticles show remarkable undercoolings: exceptional values ΔT∕Tm≅0.5 were previously reported for confined Ga droplets in the 100–1000nm range. This was considered a characteristic limiting temperature Ga. We here give evidence that 3–15nm range can be undercooled at least down to 90K (ΔT∕Tm⩾0.7) without crystallization. Since computations and experiments on clusters with <50 atoms contrary signatures of melting temperatures well above bulk value, result...
Abstract The pressure deri vative of the band gap, (∂ E /∂ P ) T , has been determined to be + 3 × 10 −6 e Vbar −1 for Mg 2 Sn by measurements derivative electrical conductivity. Similar on Si and Ge were inconclusive, but estimates this parameter made from shift optical obsorption edge with pressure. = (0 ± 0.5) both compounds. similarity coefficients suggests that symmetries edges compounds are similar, while either conduction edge, valence or in may have a different symmetry.
The machine described in this document is an advanced Source of up to 20 MeV Gamma Rays based on Compton back-scattering, i.e. collision intense high power laser beam and a brightness electron with maximum kinetic energy about 720 MeV. Fully equipped collimation characterization systems, order generate, form fully measure the physical characteristics produced Ray beam. quality, phase space density, two colliding beams will be such that emitted ray characterized by tunability, spectral...
The breakthrough provided by plasma-based accelerators enabled unprecedented accelerating fields boosting electron beams to gigaelectronvolt energies within a few centimeters [1-4]. This, in turn, allows the realization of ultracompact light sources based on free-electron lasers (FELs) [5], as demonstrated two pioneering experiments that reported observation self-amplified spontaneous emission (SASE) driven plasma-accelerated [6,7]. However, lack stability and reproducibility due intrinsic...
Quantum confinement effects in Ge nanocrystals the size range 26–130 Å have been investigated both on electronic joint density of states and Raman spectra. The high degree crystallinity particles as well minimized interaction with matrix allow detection shift broadening TO peak, which can be compared theoretical expectations based phonon confinement. evolution absorption spectra their dependence nanocrystal dimensions related.
In this paper we report absorption measurements in the range 0.6--6.0 eV, performed at 77 K on Ge nanocrystals grown by a self-organization process applied to semiconductor. Evidence of relevant blueshift ${\mathit{E}}_{2}$ and weakening ${\mathit{E}}_{1}$ with size reduction is obtained. This behavior interpreted terms quantum confinement connection different nature two structures. \textcopyright{} 1996 The American Physical Society.
A negative capacitance (NC) effect in a low-frequency range (4–8×105Hz), previously shown to take place mainly semiconductor structures, is evidenced nanometric system constituted by metallic (Ga) nanoparticles embedded an insulating (SiOxwithx~1) matrix. The dependence of the NC phenomenon on time-dependent transient current through evidenced. remarkable enhancement with size reduction manifested. physical mechanism responsible for inertia appears be related space charges located at...
The authors present a methodological examination of several formulations developed to solve different kinds inverse electromagnetic problems. Some general numerical the problems are presented that defined regardless nature specific problem. It is shown approaches can be drawn from these formulations, according and purpose investigations. most significant aspects problems, such as existence, uniqueness, stability solution discussed in detail together with applicable regularization...
We have studied experimentally and theoretically the thermoreflectance of $2H$-Ta${\mathrm{Se}}_{2}$ in neighborhood plasmon resonance near 1 eV, as a function temperature. An extensive red shift change width (a narrowing at first, then broadening) occur one heats up through 90-120-K range where charge-density waves (CDW) disappear. From close inspection dielectric response frequency temperature we find that optical transitions disappear 0.2-0.8-eV region correspondence with weakening CDW...
Brillouin scattering of light off surface acoustic phonons has been used to study the size-dependent melting transition tin nanocrystals embedded in a silica film on Si(100) substrate. A jump spectral shift phonon peaks was detected across temperature and nature assessed by vanishing Bragg peaks. simple effective medium treatment elastic constants containing solid/liquid inclusions together with numerical computation spectrum explains observed behavior. strong central peak also...
High spatial resolution Fourier transform absorption measurements were performed with polarized light on oxygen precipitates grown in silicon samples briefly annealed. We demonstrate that the wave-number position and intensity of 1230-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ band, directly related to precipitates, give information regarding stoichiometry oxide constituting such their density. In particular, our are made amorphous suboxides, mainly ${\mathrm{SiO}}_{1.8}$, 5 ppm local...