F. Flora

ENEA, Roma, Latium, Italy

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Publications (215)210.88 Total impact

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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.
    Journal of Microscopy 02/2015; DOI:10.1111/jmi.12226 · 2.15 Impact Factor
  • Short Wavelength Laboratory Sources, Principles and Practices, Edited by D. Bleiner, J. Costello, F. Dortan, G. O'Sullivan, L. Pina, A. Michette, 01/2015: pages 245-269; RCS Publishing.
  • Short Wavelength Laboratory Sources, Principles and Practices, Edited by D. Bleiner, J. Costello, F. Dortan, G. O'Sullivan, L. Pina, A. Michette, 01/2015: pages 270 - 282; RSC Publishing.
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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
    ENEA Technologies for Security, Edited by R. fantoni, P. Di Lazzaro, 12/2014: chapter Nuclear: pages 108-113; ENEA.
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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.
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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.
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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.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 08/2013; 720:168–172. DOI:10.1016/j.nima.2012.12.008 · 1.32 Impact Factor
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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.
    Applied Surface Science 05/2013; 272:13–18. DOI:10.1016/j.apsusc.2012.03.155 · 2.54 Impact Factor
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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.
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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.
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    Knowledge, Diagnostics and Preservation of Cultural Heritage, Edited by P. Clemente, P. Di Lazzaro, R. Giorgi, 01/2012: chapter Is this artwork original or is it a copy? The answer by a new anti-counterfeiting tag: pages 162-168; ENEA.
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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.
    Proceedings of SPIE - The International Society for Optical Engineering 01/2012; DOI:10.1117/12.2010400 · 0.20 Impact Factor
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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.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/2010; DOI:10.1016/j.nima.2010.02.089 · 1.32 Impact Factor
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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.
    Journal of Non-Crystalline Solids 08/2010; 356:1968-1971. DOI:10.1016/j.jnoncrysol.2010.05.037 · 1.72 Impact Factor
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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.
    Journal of Physics B Atomic Molecular and Optical Physics 08/2010; 43(17):175701. DOI:10.1088/0953-4075/43/17/175701 · 1.92 Impact Factor
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    ABSTRACT: The use of LiF thin films and single crystals was proposed and tested as X-ray imaging detector based on optically stimulated luminescence from visible-emitting color centers. The main peculiarities of this detector – i.e. high spatial resolution on a large field of view, wide dynamic range, versatility and simplicity of use – make it very promising as X-ray imaging plate for applications in photonic devices, biology and material science, as well as in the characterization of intense X-ray sources. In order to investigate the response and the sensitivity of this detector to soft X-rays, a suitable characterization of colored thin layers is performed by means of optical spectrophotometry and photoluminescence spectroscopy for samples colored under different irradiation conditions.
    Journal of Luminescence 12/2009; 129(12):1964-1967. DOI:10.1016/j.jlumin.2009.04.035 · 2.37 Impact Factor
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    ABSTRACT: This study is related to the application of the X-ray dual-energy microradiography technique together with the atomic absorption spectroscopy (AAS) for the detection of lead on Zea mays stem, ear, root, and leaf samples. To highlight the places with lead intake, the planar radiographs taken with monochromatic X-ray radiation in absorption regime with photon energy below and above the absorption edge of a given chemical element, respectively, are analyzed and processed. To recognize the biological structures involved in the intake, the dual-energy images with the lead signal have been compared with the optical images of the same Z. mays stem. The ear, stem, root, and leaf samples have also been analyzed with the AAS technique to measure the exact amount of the hyperaccumulated lead. The AAS measurement revealed that the highest intake occurred in the roots while the lowest in the maize ears and in the leaf. It seems there is a particular mechanism that protects the seeds and the leaves in the intake process.
    Microscopy Research and Technique 12/2009; 73(6):638-49. DOI:10.1002/jemt.20805 · 1.17 Impact Factor
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    ABSTRACT: Debris mitigation is still a critical issue for the development of extreme ultraviolet projection lithography (EUVL). Here, we describe the analysis of the efficiency of the debris-mitigation system (DMS) presently in use in the laser–plasma–source micro-exposure tool (MET) operating at the Frascati ENEA Research Center. Basic to such an analysis is a code specifically developed for processing the images of debris-flux-exposed glass slides. The code stands out as a tool for further plasma debris-related analyses.
    Applied Physics B 08/2009; 96(2):479-490. DOI:10.1007/s00340-009-3583-z · 1.63 Impact Factor
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    ABSTRACT: We present a low-cost microexposure tool for projection lithography at 14.4 nm we have designed and operated at the ENEA Research Centre, Frascati. It is a laboratory-scale system based on a Schwarzschild-type projection optics which uses a laser-plasma soft X-ray source, equipped with a patented debris mitigation system in order to preserve the collector optics. As a preliminary result, we achieved a 90-nm optical resolution patterning on commercial resist. A sharp improvement in resolution size is expected when operating this tool by a large-output energy excimer laser in order to obtain a single-shot patterning.
    IEEE Transactions on Plasma Science 05/2009; DOI:10.1109/TPS.2008.2011271 · 0.95 Impact Factor

Publication Stats

1k Citations
210.88 Total Impact Points


  • 1990–2013
    • ENEA
      • • Applied Physics Division
      • • Frascati Research Centre
      Roma, Latium, Italy
  • 2002
    • Brno University of Technology
      • Institute of Physical Engineering
      Brno, South Moravian Region, Czech Republic
  • 2001
    • University of Pécs
      Fuenfkirchen, Baranya, Hungary
  • 2000
    • Hebrew University of Jerusalem
      Yerushalayim, Jerusalem, Israel
  • 1997
    • École Polytechnique
      Paliseau, Île-de-France, France