RICARDO ELGUL SAMAD

Resumo

Has graduation at Bacharelado Em Física by Instituto de Física da Usp (1993) , specialization at V Escola Jorge André Swieca de Óptica Quântica by Centro Brasileiro de Pesquisas Físicas (1996) , specialization at 1a Escola de Óptica Aplicada by Instituto de Física da Usp (1998) , specialization at Training Course On Instrumentation For Ultrashort by International Centre For Science And High Technology (2002) , specialization at An Introduction to Femtosecond Laser Techniques by The International Society For Optical Engineering (2005) , specialization at IV Escola Jorge André Swieca de Óptica Quântica by Universidade Estadual de Campinas (1994) , specialization at Workshop On Thin Films by International Centre For Theoretical Physics (1999) , specialization at Winter College On Optics by International Centre For Theoretical Physics (1998) , specialization at Winter College On Ultrafast Non Linear Optics by International Centre For Theoretical Physics (2002) , master's at Física do Estado Sólido by Instituto de Física da Usp (1997) and Ph.D. at Física do Estado Sólido by Instituto de Física da Usp (2006) . Currently is of Instituto de Pesquisas Energéticas e Nucleares, Revisor de periódico of Applied Optics, Revisor de periódico of Optics Letters, of Universidade de São Paulo, Revisor de periódico of Journal of Applied Physics, of Comissão Nacional de Energia Nuclear, Revisor de periódico of OPTICS EXPRESS, Revisor de periódico of OPTICS AND LASERS IN ENGINEERING, Revisor de periódico of JOURNAL OF APPLIED PHYSICS, Revisor de projeto de fomento of Conselho Nacional de Desenvolvimento Científico e Tecnológico, Revisor de projeto de fomento of Fundação de Amparo à Pesquisa do Estado de São Paulo, Revisor de projeto de fomento of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Revisor de periódico of Papers in Physics, Revisor de periódico of Optics and Laser Technology, Membro de corpo editorial of SBFoton Newsletter, of University of Nebraska/Lincoln e of Centro Tecnológico da Marinha Em Sao Paulo. Has experience in the area of Physics , with emphasis on Física da Matéria Condensada. Focused, mainly, in the subjects: femtossegundos, Terawatt, Cr:LiSAF, Amplificacao de Pulsos Laser, Lasers. (Text obtained from the Currículo Lattes on November 25th 2021)


Ricardo Elgul Samad bacharelou-se em Física em 1993, obteve o seu mestrado em Física do Estado Sólido em 1997, e concluiu o doutorado também em Física do Estado Sólido em 2006, todos pelo Instituto de Física da USP. Atualmente é Pesquisador do Centro de Lasers e Aplicações Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP). Publicou 69 artigos em periódicos especializados que possuem mais de 550 citações, 3 capítulos de livros e mais de 90 trabalhos em anais de eventos, além de ter submetido 2 pedidos de patente. Desde a sua Iniciação Científica trabalha no desenvolvimento e em aplicações de lasers de estado sólido, e no seu doutorado iniciou atividades de pesquisa com lasers de pulsos ultracurtos. Atualmente trabalha com aplicações de pulsos ultracurtos e a interação destes com a matéria, como na ablação e usinagem de sólidos por laser, geração de plasma induzida por pulsos ultracurtos e modificação de materiais resultante de estados extremos de temperatura e pressão gerados pelos pulsos ultracurtos, e técnicas de geração de harmônicos para viabilizar novas fontes de luz na região do UV profundo e raios X moles. Recentemente tem trabalhado com aceleração de partículas por pulsos laser ultracurtos. (Texto extraído do Currículo Lattes em 25 nov. 2021)

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Resultados de Busca

Agora exibindo 1 - 10 de 221
  • Artigo IPEN-doc 30412
    Evaluation of adhesive strength in dentin iradiated with ultra short pulse laser (FS) at various energy densities using two adhesive strategies
    2024 - PENHA-JUNIOR, T.; RODRIGUES, M.A.P.; PECORARI, V.; VIEIRA JUNIOR, N.D.; ZEZELL, D.M.; SAMAD, R.E.; DUTRA-CORREA, M.
    Goal: The study evaluated the adhesive strength of the tooth-restoration interface, promoted by ultrashort pulse laser irradiation, and its influence on the microtensile adhesive strength (µTBS) with different adhesive strategies. Method: Fifty healthy teeth were evaluated, restored with the Single Bond Universal adhesive, using two adhesion strategies: ecth-and-rinse, total acid etching (E) and self-etch, self-etching (SE). To evaluate the adhesive interface, the samples were divided into groups SE (self-etch) and E (etch), and each group was irradiated with pulse fluences of 2 J/cm2, 4 J/cm2, 6 J/cm2 and 8 J/cm2. After irradiation, and restorations were carried out with Z350XT resin, the samples were sectioned with cuts perpendicular to each other, producing toothpicks, which were subjected to microtraction. The Bartlet and Shapiro-Wilks tests were performed and then Two-way ANOVA was applied with 2 additional treatments. When observing differences between factors or interactions, the Dunnett test was applied to compare groups with Controls and Tukey for multiple two-by-two comparisons between the transformed means (α<0.05). The percentages of failure types (µTBS) were calculated in the different groups and the Fisher's Exact test was applied (α<0.05). Result: The results demonstrate that laser irradiation (fs), regardless of the energy density used, did not interfere with the performance of the material at the adhesive interface without prior conditioning, as the values obtained were similar to each other (32-35 MPa). Conclusion: It was concluded that irradiation with different energy densities did not change the adhesive strength of the SE groups, as the groups had similar results between themselves and the Control. However, acid conditioning affected the irradiated groups, as the Control (with acid) presented higher values with a statistical difference in relation to the others.
  • Artigo IPEN-doc 30177
    Impact of He+N2 concentration on self-modulated laser wakefield acceleration driven by pulses of a few TW
    2023 - MOLDONADO, EDISON P.; SAMAD, RICARDO E.; ZUFFI, ARMANDO V.F.; SANTOS, JHONATHA R. dos; VIEIRA JUNIOR, NILSON D.
    Laser wakefield electron acceleration with ionization injection has rarely been studied in the low-power, selfmodulated case. We performed simulations of such regimes using a mixture of He and N2 gases and driven by laser pulses with peak powers around 1 TW. Analyses show the generation of electron bunches with an average energy of up to 70 MeV, an energy spread as low as 18%, and an emittance as good as a fraction of a mm mrad. The obtained electron beam parameters lead to several trade-offs as a function of N2 concentration, allowing for many different designs.
  • Artigo IPEN-doc 30194
    Ionization model to estimate the density and temperature of fs-laser-induced plasmas in air
    2023 - ZUFFI, ARMANDO V.F.; SANTOS, JHONATHA R. dos; SAMAD, RICARDO E.
    We present a simple ionization model to assess the density of plasmas created in air by ionization induced by the electric field of ultrashort laser pulses. It calculates the average ionization induced by the laser taking into account the known threshold intensities for each ionic state, the beam spatial profile and the atmospheric composition, estimating the plasma density. The model density predictions are compared to experimental results obtained by a time-resolved Mach-Zehnder-like interferometer, and are also used as entry parameters to evaluate the plasma temperature by the Saha equation.
  • Artigo IPEN-doc 30175
    Simulation of self-modulated laser wakefield acceleration using few TW in downramp injection and ionization injection regimes
    2023 - MALDONADO, EDISON P.; SAMAD, RICARDO E.; ZUFFI, ARMANDO V.F.; VIEIRA JUNIOR, NILSON D.
    Simulations of transitional self-modulated laser wakefield acceleration driven by laser pulses of a few terawatts are discussed, comparing a downramp-based injection regime with an ionization injection regime. We demonstrate that a configuration using an N2 gas target and a laser pulse of ∼75mJ with ∼2TW peak power is a good alternative as a high repetition rate system that produces electrons of many tens of MeV, pC charge, and emittance of the order of 1 mm mrad.
  • Artigo IPEN-doc 30187
    Development of an Imaging System for an Electron Spectrometer for laser-accelerated electrons
    2023 - BRANDAO, VITORIA M.C.; SAMAD, RICARDO E.
    We present the results of an electron spectrometer with an imaging system to determine the energy spectrum of laser accelerated electrons. The spectrometer is composed by a region with a constant magnetic field that deflects relativistic electrons according to their kinetic energy, and a luminescent screen into which the electrons impinge. The imaging system optimizes the collection of the screen luminescence, which is inside a vacuum chamber, and magnifies it, through a window, into a CCD in atmosphere that records the light pattern, from which the energy spectrum is recovered.
  • Artigo IPEN-doc 30174
    Femtosecond laser-plasma dynamics study by a time-resolved Mach–Zehnder-like interferometer
    2023 - ZUFFI, ARMANDO V.F.; SANTOS, JHONATHA R. dos; MALDONADO, EDISON P.; VIEIRA JUNIOR, NILSON D.; SAMAD, RICARDO E.
    Side-view density profiles of a laser-induced plasma were measured by a home-built, time-resolved, Mach–Zehnder-like interferometer. Due to the pump-probe femtosecond resolution of the measurements, the plasma dynamics was observed, along with the pump pulse propagation. The effects of impact ionization and recombination were evidenced during the plasma evolution up to hundreds of picoseconds. This measurement system will integrate our laboratory infrastructure as a key tool for diagnosing gas targets and laser-target interaction in laser wakefield acceleration experiments.
  • Resumo IPEN-doc 29573
    FTIR imaging on glass substrates evaluation of histological skin burn injuries specimens treated by femtosecond laser pulses
    2022 - ZEZELL, DENISE; CASTRO, PEDRO; DEL-VALLE, MATHEUS; CAMILLO-SILVA, CARLOS; SAMAD, RICARDO; DE ROSSI, WAGNER; SANTOS, MOISES
    Burn injuries continue to be one of the leading causes of unintentional death and injury in low- and middle-income countries [1]. Burns are considered an important public health problem, because in addition to physical problems that can lead the patient to death, they cause psychological and social damage. An estimated 180,000 deaths every year are caused by burns [2]. The use of infrared (IR) spectroscopy for studying biological specimens is nowadays a wide and active area of research. The IR microspectroscopy has proved to be an ideal tool for investigating the biochemical composition of biological samples at the microscopic scale, as well as its fast, sensitive, and label-free nature [3]. IR image spectral histopathology has shown great promise as an important diagnostic tool, with the potential to complement current pathological methods, reducing subjectivity in biopsy samples analysis. However, the use of IR transmissive substrates which are both fragile and prohibitively very expensive, hinder the clinical translation. The goal of this study is to evaluate the potential of discriminating healing process, in burned skin specimens treated with ultrashort pulses laser 3 days after the burn. This study is considering a previous paper [4], in which it analyzed only micro-ATR-FTIR spectra of a frozen sample point. The specimens were obtained from third degree burn wound. The wounds treatment were performed three days after the burn, and the animals were sacrificed 3 and 14 days post-treatment. Using coverslipped H&E stained tissue on glass from previous histopathological analysis and applying the analytical techniques PCA and K-means on N−H, O−H, and C−H stretching regions occurring at 2500−3800 cm−1 (high wavenumber region), were possible to discriminate burned epidermal and dermal regions from irradiated in same regions on sample. In the figures is shown the average spectrum at (a) day 3 and (b) day 14. , in both there were increase of burned+laser treated bands. The great potential of this study was to analyse coverslipped H&E stained tissue on glass, without compromising the histopathologist practices and contribute for clinical translation.
  • Artigo IPEN-doc 29358
    Time-resolved femtosecond laser-plasma measurements by a Mach-Zehnder-like interferometer
    2022 - ZUFFI, ARMANDO V.F.; MALDONADO, EDISON P.; VIEIRA JUNIOR, NILSON D.; SAMAD, RICARDO E.
    This work reports measurements of the density profile of laser-generated plasmas by a home-built time-resolved Mach-Zehnder-like interferometer. This device will integrate our laboratory infrastructure for laser wakefield acceleration experiments.
  • Artigo IPEN-doc 29352
    Simulation of a laser wakefield accelerator in downramp injection regime suitable for high repetition rates
    2022 - MALDONADO, EDISON P.; SAMAD, RICARDO E.; ZUFFI, ARMANDO V.F.; VIEIRA JUNIOR, NILSON D.
    We discuss the results of simulating a laser wakefield accelerator in the 50 MeV range suitable for repetition rates > 10 Hz using commercial lasers and compare with other approaches for this purpose.
  • Artigo IPEN-doc 29351
    Observation of third-harmonic saturation in helium due to ionization depletion
    2022 - ZUFFI, ARMANDO V.F.; VIEIRA JUNIOR, NILSON D.; SAMAD, RICARDO E.
    We report the saturation of the third harmonic generated in Helium by ultrashort laser pulses, and describe the observed plateau based on the depletion of the electrons generating the harmonics in a restricted interaction volume.