F. Flora

ENEA, Roma, Latium, Italy

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Publications (222)219.9 Total impact

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    Full-text · Technical Report · Nov 2015
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    Full-text · Dataset · Sep 2015
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    ABSTRACT: We present a novel electro-optical solar compass that is able to determine the true North direction with an accuracy better than 1/100 of degree, superior to that of any other magn etic or electronic compass that does not resort to differential GPS. The compass has an electr onic sensor to determine the line of sight of the Sun and a simple but effective algorithm to calculate the position of the Sun. The excellent results obtained during the experimental tests demonstrate the advantage s of this compa ss, wh ich is also compact and not expensive.
    Full-text · Article · Aug 2015 · Optics Letters
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    ABSTRACT: In this paper, the use of lithium fluoride (LiF) as imaging radiation detector to analyse living cells by single-shot soft X-ray contact microscopy is presented. High resolved X-ray images on LiF of cyanobacterium Leptolyngbya VRUC135, two unicellular microalgae of the genus Chlamydomonas and mouse macrophage cells (line RAW 264.7) have been obtained utilizing X-ray radiation in the water window energy range from a laser plasma source. The used method is based on loading of the samples, the cell suspension, in a special holder where they are in close contact with a LiF crystal solid-state X-ray imaging detector. After exposure and sample removal, the images stored in LiF by the soft X-ray contact microscopy technique are read by an optical microscope in fluorescence mode. The clear image of the mucilaginous sheath the structure of the filamentous Leptolyngbya and the visible nucleolus in the macrophage cells image, are noteworthiness results. The peculiarities of the used X-ray radiation and of the LiF imaging detector allow obtaining images in absorption contrast revealing the internal structures of the investigated samples at high spatial resolution. Moreover, the wide dynamic range of the LiF imaging detector contributes to obtain high-quality images. In particular, we demonstrate that this peculiar characteristic of LiF detector allows enhancing the contrast and reveal details even when they were obscured by a nonuniform stray light. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.
    Full-text · Article · Feb 2015 · Journal of Microscopy
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    ABSTRACT: A discharge-produced-plasma (DPP) source emitting in the extreme ultraviolet (EUV) spectral region is running at the ENEA Frascati Research Centre. The plasma is generated in low-pressure xenon gas and efficiently emits 100-ns duration radiation pulses in the 10–20-nm wavelength range, with an energy of $20~\text{mJ}/\text{shot}/\text{sr}$ at a 10-Hz repetition rate. The complex discharge evolution is constantly examined and controlled with electrical measurements, while a ns-gated CCD camera allowed observation of the discharge development in the visible, detection of time-resolved plasma-column pinching, and optimization of the pre-ionization timing. Accurately calibrated Zr-filtered PIN diodes are used to monitor the temporal behaviour and energy emission of the EUV pulses, while the calibration of a dosimetric film allows quantitative imaging of the emitted radiation. This comprehensive plasma diagnostics has demonstrated its effectiveness in suitably adjusting the source configuration for several applications, such as exposures of photonic materials and innovative photoresists.
    Full-text · Article · Jan 2015

  • No preview · Chapter · Jan 2015

  • No preview · Chapter · Jan 2015
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    ABSTRACT: We describe the technique and apparatus to write invisible patterns on thin tags of alkali halides by using an extreme ultraviolet radiation source. We have experimentally demonstrated that lithium fluoride thin-films tags written using this method are almost impossible to counterfeit, and offer a much better protection than the available anti-counterfeiting techniques. The results of preliminary tests of exposure to γ-, x-and β-radiation emitted by several radio-nuclides, like Co-60, Cs-137, Na-22, and Ba-133 are promising for the use of these tags to track radioactive materials, in order to fight phenomena impacting security, like the illicit disposal and traffic in radioactive waste. Il presente articolo descrive la tecnica e gli strumenti per scrivere disegni invisibili su sottili etichette di metalli alcalini terrosi utilizzando una fonte di radiazione nell'estremo ultravioletto. È stato dimostrato sperimentalmente che il nostro metodo di scrittura rende praticamente impossibile la contraffazione di etichette realizzate con una pellicola sottile di fl uoruro di litio e offre una protezione molto migliore rispetto alle tecniche anticontraffazione attualmente disponibili. I risultati di test preliminari di esposizione a raggi γ, x e β emessi da diversi radionuclidi, quali Co-60, Cs-137, Na-22, e Ba-133, si sono rivelati promettenti per poter usare queste etichette per tracciare materiali radioattivi, al fi ne di contrastare fenomeni che mettono a rischio la sicurezza, quali ad esempio lo smaltimento e il traffi co illecito di scorie radioattive. Scrittura e tracciamento di materiali radioattivi: una possibile soluzione hi-tech
    Full-text · Chapter · Dec 2014
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    ABSTRACT: Numerose applicazioni richiedono di conoscere l’orientamento di una determinata direzione o dell’orientamento di un oggetto rispetto alla direzione del Nord geografico con elevata accuratezza. La bussola brevettata è in grado di assicurare una precisione molto più elevata dei modelli sul mercato. Many applications need to know, with a high level of accuracy, the orientation of a given direction or object with respect to the geographical North. The patented compass can ensure a much higher precision than the models currently available on the market.
    Full-text · Article · Nov 2014
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    ABSTRACT: a b s t r a c t Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10–100 GV m À 1), enabling acceleration of electrons to GeV energy in few centimetres. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators; radiofrequency-based accelerators, in fact, are limited in the accelerating field (10–100 MV m À 1) requiring therefore kilometric distances to reach the GeV energies, but can provide very bright electron bunches. Combining high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC-LAB [1,2]. In particular, here we focus on the ionization process; we show a simplified model to study the evolution of plasma induced by discharge, very useful to design the discharge circuit able to fully ionize the gas and bring the plasma at the needed temperature and density. & 2013 Published by Elsevier B.V.
    Full-text · Dataset · Oct 2013
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    ABSTRACT: Schwarzschild objectives are widely used in the extreme ultraviolet (EUV)/soft X-ray spectral region both as reduction and magnification optics, e.g. for small-field projection lithography and microscopy, respectively. When using a Schwarzschild objective as a micro-exposure tool (MET) at high spatial resolution (half-pitch≤0.1 μm), in addition to the tight requirements on the design and surface figure for the single optics, also an accurate alignment between the two mirrors is needed to reach the planned spatial imaging detail. Ideally, at-wavelength alignment should be done in order to overcome limitations due to diffractive effects. While this can be easily performed on synchrotron beam lines, it becomes time expensive (and components consuming) on low-power laboratory plasma sources. In this work we propose and test a new technique to align a EUV Schwarzschild objective by means of ultraviolet light. The aligned objective allowed the attainment of lithographic patterning with edge response of 90 nm, as part of the laboratory-scale MET for EUV projection lithography realized at the ENEA Frascati Research Centre.
    Full-text · Article · Aug 2013 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
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    ABSTRACT: While developing a laboratory-scale micro-exposure tool for extreme ultraviolet (EUV) projection lithography which uses a laser-produced plasma emitting EUV pulsed radiation, we faced the problem of suppressing the various debris (ions, neutrals, particulate, clusters, droplets) emitted by the plasma target. The suppression of debris is a crucial task in the frame of EUV projection lithography, mainly because debris seriously limit both lifetime and performance of the expensive optics and filters put close to the plasma source. In this paper we present the experimental measurements of main debris characteristics (velocity, size, charge, momentum, spectral energy, spatial distribution). Then, we present the operating results of a patented debris mitigation systems (DMS) specifically designed to suppress debris with the measured characteristics. We achieved reduction factors ∼800 for atoms and nm-size clusters, and ∼1600 for particles larger than 500 nm. These results are at the forefront in this field. The excellent performance of our DMS was a breakthrough to achieve a 90-nm patterning on commercial resists by our micro-exposure tool EUV projection lithography.
    Full-text · Article · May 2013 · Applied Surface Science
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    ABSTRACT: An analytical method, based on an approximated solution of Keplero’s equations, is here proposed. This method allows, in a simple and fast way, to calculate the sun position at any time and everywhere in the world at an angular accuracy of 1 minute. The algorithm can easily be implemented in economic microprocessors so that any sun tracking device for concentrating solar installations could be guided toward the sun at high accuracy without the need of optical components. Two methods for a correct trackers installation are finally described.
    Full-text · Article · Dec 2012
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    Luca Mezi · Francesco Flora
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    ABSTRACT: Sommario In questo rapporto vengono descritti i lavori di installazione, miglioramento e caratterizzazione della sorgente di radiazione nell'estremo ultravioletto a scarica elettrica dell'ENEA (UTAPRAD–SOR). La sorgente, inizialmente progettata e realizzata in collaborazione tra l'ENEA ed il Dipartimento di Fisica dell'Universit a dell'Aquila, ` e stata trasferita all'ENEA (Frascati) nell'Aprile 2010, priva, per o, di molti componenti fondamentali. Per mettere in funzione la sorgente, non disponendo di fondi dedicati, ` e stato necessario riutilizzare, modificandoli oppor-tunamente, materiali e dispositivigì a presenti all'ENEA. Inoltre, per migliorare il funzionamento e le caratteristiche della sorgente, sì e provveduto a modificarne radicalmente varie parti, affrontando diverse problematiche fisiche nell'analisi dei principi di funzionamento della sorgente. Attualmente la sorgentè e operativa e le sue caratteristiche la rendono idonea per varie applicazioni. Con l'intento di fornire una prima base ad un eventuale futuro studente, in questo rapporto i principi fisici di funzionamento della sorgente e le problematiche affrontate sono stati trattati anche da un punto di vista didattico. Parole chiave: Estremo UltraVioletto (EUV); Plasma prodotto tramite sca-rica elettrica; Effetto pinch; Circuiti in alta tensione. Abstract In this report we describe the installation, upgrade and characterisation of the ENEA (UTAPRAD–SOR) extreme–ultraviolet electric discharge source. In April 2010 the source, initially developed in the framework of a collaboration between ENEA and the Physics Department of the University of L'Aquila, has been trans-ferred to ENEA (Frascati), but without many important components. To make the source working, having no dedicated funds, it was necessary to reutilise and properly modify materials and devices already present in ENEA. In order to im-prove some source features, several critical components of the source have been totally redesigned, analyzing the source working principles and solving various physical problems. Now the source is operating and, due to its characteristics, it is suitable for many applications. With the aim of giving a possible future student a starting point, in this report the source working principles and the scientific problems that we ran into, have been also didactically treated.
    Full-text · Technical Report · Jul 2012
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    Full-text · Chapter · Jan 2012
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    ABSTRACT: We present a recently patented apparatus which consists of an extreme ultraviolet radiation source writing invisible patterns on thin tags of alkali halides. The tags patterned using this method are almost impossible to counterfeit, and offer a much better protection against fakes than available anti-counterfeiting techniques. We will discuss if this novel technology is ready for industrial production of anti-counterfeiting tags.
    Full-text · Article · Jan 2012 · Proceedings of SPIE - The International Society for Optical Engineering
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    Full-text · Article · Jan 2011
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    ABSTRACT: Among insulating materials containing point defects, lithium fluoride (LiF) is a radiation-sensitive alkali halide well known in dosimetry and as active medium in light-emitting devices and lasers. Electronic point defects can be produced in LiF crystals and films by different kinds of radiation. Some of these electronic defects, known as colour centres, are optically active, with broad absorption and emission bands in the visible spectral range. Novel thin-film imaging detectors for extreme ultraviolet and soft X-rays, based on photoluminescence from aggregated colour centres in LiF, have been proposed and are currently under development, successfully extending their operation also in the hard X-ray region, up to 10 keV. Among the main peculiarities of LiF-based detectors, there are intrinsic high spatial resolution, in principle limited only by the point defect size, large field of view and wide dynamic range. These imaging detectors feature great versatility, as they can be grown in the form of thin films on different substrates by well-assessed physical deposition techniques. We present the promising results obtained using different X-ray laser–plasma sources in the field of nanotechnology, biology and in material science in view of future perspectives of research and development.
    No preview · Article · Nov 2010 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
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    ABSTRACT: We present the realization and characterization of photoluminescent nanometric periodic patterns of color centers (CCs) in lithium fluoride (LiF) produced by an interferometric method based on a coherent soft X-ray laser beam. Among broad-band light-emitting materials, LiF, in the form of crystals and thin films, is a radiation-sensitive material well known in dosimetry and as a laser-active medium in optically pumped photonic devices. Primary and aggregate electronic defects can be produced in LiF by low-penetrating electromagnetic radiation, like soft X-ray. The high brightness and spatial coherence of a capillary discharge laser, with the emission wavelength of 46.9 nm, allowed writing periodic lines of stable CCs at a nanometric scale emitting visible light under optical pumping. Interferometric encoding of luminescent nano-structures in LiF proved to be a powerful tool for producing low-dimensionality optical devices for photonic applications.
    No preview · Article · Aug 2010 · Journal of Non-Crystalline Solids
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    ABSTRACT: The Los Alamos suite of atomic codes is used to model several high-resolution spectral measurements from recent laser-produced plasma experiments involving barium fluoride targets. The spectral range of observation is from 7.8 to 9.5 Å and the observed lines correspond to 3–5, 3–6, 3–7 and 3–8 transitions of principal quantum number, for Ga-like through Co-like barium ions. The observed spectra are complicated because of many overlapping lines from the various ion stages in a small wavelength region. A MUTA model that includes many configurations is compared to a detailed level-to-level collisional-radiative model that includes fewer configurations. Spectra are calculated to show the sensitivity to plasma temperature, density and size. The contributions to the spectra for the individual ion stages are also presented. The model calculations are in reasonable agreement with experiment.
    No preview · Article · Aug 2010 · Journal of Physics B Atomic Molecular and Optical Physics

Publication Stats

2k Citations
219.90 Total Impact Points

Institutions

  • 1990-2013
    • ENEA
      • Applied Physics Division
      Roma, Latium, Italy
  • 2002
    • University of Rome Tor Vergata
      Roma, Latium, Italy
    • Brno University of Technology
      • Institute of Physical Engineering
      Brno, South Moravian Region, Czech Republic
  • 2001
    • Università degli Studi dell'Aquila
      • Department of Chemistry, Chemical Engineering and Materials
      Aquila, Abruzzo, Italy
  • 2000
    • Hebrew University of Jerusalem
      Yerushalayim, Jerusalem, Israel
    • University of Milan
      Milano, Lombardy, Italy
  • 1997
    • École Polytechnique
      Paliseau, Île-de-France, France