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Navegando Artigo de evento por Autor "Abrantes A."

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  • Artigo de evento
    SOLAR-T : Terahertz photometers to observe solar flare emission on stratospheric balloon flights
    Kaufmann P.; Abrantes A.; Bortolucci E.C.; Correia E.; Diniz J.A.; Fernandez G.; Fernandes L.O.T.; Gimenez De Castro C.G.; Godoy R.; Hurford G.; Kudaka A.S.; Lebedev M.; Lin R.P.; MacHado N.; Makhmutov V.S.; Marcon R.; Marun A.; Nicolaev V.A.; Pereyra P.; Raulin J.-P.; Da Silva C.M.; Shih A.; Stozkhov Y.I.; Swart J.W.; Timofeevsky A.V.; Valio A.; Villelad T.; Zakia M.B. (2012)
    A new solar flare spectral component has been found with intensities increasing for larger sub-THz frequencies, spectrally separated from the well known microwaves component, bringing challenging constraints for interpretation. Higher THz frequencies observations are needed to understand the nature of the mechanisms occurring in flares. A twofrequency THz photometer system was developed to observe outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. 76 mm diameter telescopes were designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions at 3 and 7 THz. Golay cell detectors are preceded by low-pass filters to suppress visible and near IR radiation, band-pass filters, and choppers. It can detect temperature variations smaller than 1 K with time resolution of a fraction of a second, corresponding to small burst intensities. The telescopes are being assembled in a thermal controlled box to which a data conditioning and acquisition unit is coupled. While all observations are stored on board, a telemetry system will forward solar activity compact data to the ground station. The experiment is planned to fly on board of long-duration stratospheric balloon flights some time in 2013-2015. One will be coupled to the GRIPS gamma-ray experiment in cooperation with University of California, Berkeley, USA. One engineering flight will be flown in the USA, and a 2 weeks flight is planned over Antarctica in southern hemisphere summer. Another long duration stratospheric balloon flight over Russia (one week) is planned in cooperation with the Lebedev Physics Institute, Moscow, in northern hemisphere summer. © 2012 SPIE.
  • Artigo de evento
    Space and ground-based new tools for THz solar flare observations
    Kaufmann P.; Abrantes A.; Bortolucci E.C.; Fernandes L.O.T.; Kropotov G.I.; Kudaka A.S.; Machado N.; Marcon R.; Nicolaev V.; Timofeevsky A. (2015)
    Recent sub-THz and 30 THz observations revealed an unexpected new spectral component, with fluxes increasing towards THz frequencies, simultaneously with the well known component peaking at microwaves, bringing challenging constraints for interpretation. The knowledge of the complete THz flare spectrum is the essential requirement for understanding the origin of this radiation. We present the concept, fabrication and performance of telescope photometric systems to observe solar flares at 3 and 7 THz from above the atmosphere, named SOLAR-T, and at 0.85 and 1.4 THz from the ground at a high altitude site, named HATS. The innovative optical setup allows observations of the full solar disk with high sensitivity to detect small burst transients (tens of solar flux units) with time resolution of less than one second. The SOLART space experiment uses two Golay cell detectors at the focus of 7.6 cm Cassegrain telescopes. The incoming radiation undergoes low-pass filters made of rough surface primary mirrors and membranes, 3 and 7 THz band-pass filters, and choppers. The system has been integrated to data acquisition and telemetry modules for this application. Tests comprised the whole system performance, on ambient and low pressure and temperature conditions. SOLAR-T is being integrated to U.C. Berkeley gamma-ray GRIPS experiment to be flown on a long duration stratospheric balloon mission over Antarctica. The HATS telescope utilizes the same principles, with a 46 cm rough mirror Newtonian telescope, a Golay cell sensor preceded by low pass filter, and a double window chopper, each one with band pass filters at 0.87 and 1.4 THz. HATS now undergoes operational tests in Brazil, and is planned for operations in 2015 at a site to be selected in the Andes Cordillera, above 5000 m altitude.
  • Artigo de evento
    The performance of THz photometers for solar flare observations from space
    Kaufmann P.; Fernandes L.O.T.; Kudaka A.S.; Marcon R.; Bortolucci E.C.; Machado N.; Abrantes A.; Da Silva C.M.; Nicolaev V.; Timofeevsky A.; Marun A. (2013)
    The performance of the double THz photometers system is presented. It is the first detection device conceived to observed solar flare THz emissions on board of stratospheric balloons. The system, named SOLAR-T, has been built, integrated to data acquisition and telemetry modules developed for this application, and tested. It utilizes two Golay cell detectors preceded by low-pass filters, 3 and 7 THz band-pass filters, and choppers. SOLAR-T photometers can detect relative temperature variations smaller than 1 K with sub second time resolution. It is intended to determine the still unrevealed spectral shape of the mysterious THz solar flares emissions. The experiment is planned to fly on board of two long-duration stratospheric balloon flights over Antarctica and Russia in 2014-2016. © 2013 IEEE.
  • Artigo de evento
    THz solar observations on board of a trans-Antarctic stratospheric balloon flight
    Kaufmann P.; Abrantes A.; Bortolucci E.C.; Caspi A.; Fernandes L.O.T.; Kropotov G.; Kudaka A.S.; Laurent G.; Machado N.; Marcon R.; Marun A.; Nicolaev V.; Ramirez R.F.H.; Raulin J.-P.; Saint-Hilaire P.; Shih A.; Silva C.M.; Timofeevsky A. (2016)
    © 2016 IEEE.A new system of two photometers was built to observe the Sun at 3 and 7 THz from space, named SOLAR-T. It has been flown coupled to U.C. Berkeley GRIPS experiment on a NASA stratospheric balloon flight over Antarctica, 19-30 January 2016. The mission was successfully accomplished. We describe the system performance, solar brightness determination and the first THz impulsive burst detected.