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  • 1. Emile, Olivier
    et al.
    Brousseau, Christian
    Emile, Janine
    Niemiec, Ronan
    Madhjoubi, Kouroch
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Electromagnetically Induced Torque on a Large Ring in the Microwave Range2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 5, p. 053902-Article in journal (Refereed)
    Abstract [en]

    We report on the exchange of orbital angular momentum between an electromagnetic wave and a 30 cm diameter ring. Using a turnstile antenna in the GHz range, we induce a torque on a suspended copper strip of the order of 10(-8) N m. Rotations of a few degrees and accelerations up to 4 x 10(-4) degrees/s(2) are observed. A linear dependence of the acceleration as a function of the applied power is found. There are many applications in the detection of angular momentum in electromagnetics, in acoustics, and also in the magnetization of nanostructures.

  • 2. Mari, E.
    et al.
    Tamburini, F.
    Swartzlander, G. A., Jr.
    Bianchini, A.
    Barbieri, C.
    Romanato, F.
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Sub-Rayleigh optical vortex coronagraphy2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 3, p. 2445-2451Article in journal (Refereed)
    Abstract [en]

    We introduce a new optical vortex coronagraph(OVC) method to determine the angular distance between two sources when the separation is sub-Rayleigh. We have found a direct relationship between the position of the minima and the source angular separation. A priori knowledge about the location of the two sources is not required. The superresolution capabilities of an OVC, equipped with an l = 2 N-step spiral phase plate in its optical path, were investigated numerically. The results of these investigations show that a fraction of the light, increasing with N, from the secondary source can be detected with a sub-Rayleigh resolution of at least 0.1 lambda/D.

  • 3.
    Morosan, D. E.
    et al.
    Trinity Coll Dublin, Sch Phys, Dublin 2, Ireland..
    Gallagher, P. T.
    Trinity Coll Dublin, Sch Phys, Dublin 2, Ireland..
    Fallows, R. A.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Reid, H.
    Univ Glasgow, SUPA, Sch Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland..
    Mann, G.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Bisi, M. M.
    Rutherford Appleton Lab, Sci & Technol Facil Council, RAL Space, Harwell Campus, Didcot OX11 OQX, Oxon, England..
    Magdalenic, J.
    Royal Observ Belgium, SIDC, Solar Terr Ctr Excellence, Ave Circulaire 3, B-1180 Brussels, Belgium..
    Rucker, H. O.
    Austrian Acad Sci, Commiss Astron, Schmiedlstr 6, A-8042 Graz, Austria..
    Thide, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vocks, C.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Anderson, J.
    DeutschesGeoForschungsZentrum GFZ, Helmholtz Zentrum Potsdam, Dept Geodesy & Remote Sensing 1, Telegrafenberg A17, D-14473 Potsdam, Germany..
    Asgekar, A.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;Shell Technol Ctr, Bangalore 562149, Karnataka, India..
    Avruch, I. M.
    SRON Netherlands Insitute Space Res, POB 800, NL-9700 Groningen, Netherlands.;Kapteyn Astron Inst, POB 800, NL-9700 Groningen, Netherlands..
    Bell, M. E.
    CSIRO Astron & Space Sci, 26 Dick Perry Ave, Kensington, WA 6151, Australia..
    Bentum, M. J.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;Univ Twente, 75222 Enshed, Enschede, Netherlands..
    Best, P.
    Univ Edinburgh, Royal Observ Edinburgh, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Blaauw, R.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Bonafede, A.
    Univ Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany..
    Breitling, F.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Broderick, J. W.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Brueggen, M.
    Univ Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany..
    Cerrigone, L.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Ciardi, B.
    Max Planck Inst Astrophys, Karl Schwarzschild Str 1, D-85741 Garching, Germany..
    de Geus, E.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;SmarterVision BV, Oostersingel 5, NL-9401 JX Assen, Netherlands..
    Duscha, S.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Eisloeffel, J.
    Thuringer Landessternwarte, Sternwarte 5, D-07778 Tautenburg, Germany..
    Falcke, H.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;Radboud Univ Nijmegen, Dept Astrophys IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands..
    Garrett, M. A.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;Univ Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys, Manchester M13 9PL, Lancs, England.;Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands..
    Griessmeier, J. M.
    Univ Orleans CNRS, LPC2E, F-45071 Orleans, France.;Univ Orleans, USR 704, Observatoire Paris CNRS INSU, Stn Radioastron Nancay, Route Souesmes, F-18330 Nancay, France..
    Gunst, A. W.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Hoeft, M.
    Thuringer Landessternwarte, Sternwarte 5, D-07778 Tautenburg, Germany..
    Iacobelli, M.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Juette, E.
    Ruhr Univ Bochum, Astron Inst, Univ Str 150, D-44780 Bochum, Germany..
    Kuper, G.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    McFadden, R.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    McKay-Bukowski, D.
    Univ Oulu, Sodankyla Geophys Observ, Tahtelantie 62, Sodankyla 99600, Finland.;STFC Rutherford Appleton Lab, Harwell Sci & Innovation Campus, Didcot OX11 0QX, Oxon, England..
    McKean, J. P.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;Kapteyn Astron Inst, POB 800, NL-9700 Groningen, Netherlands..
    Mulcahy, D. D.
    Univ Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys, Manchester M13 9PL, Lancs, England..
    Munk, H.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;Radboud Univ Nijmegen, Radio Lab, POB 9010, NL-6500 GL Nijmegen, Netherlands..
    Nelles, A.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Orru, E.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Paas, H.
    Univ Groningen, CIT, Groningen, Netherlands..
    Pandey-Pommier, M.
    Ctr Rech Astrophys Lyon, Observ Lyon, 9 Ave Charles Andre, F-69561 St Genis Laval, France..
    Pandey, V. N.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Pizzo, R.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Polatidis, A. G.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Reich, W.
    Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany..
    Schwarz, D. J.
    Univ Bielefeld, Fak Phys, Postfach 100131, D-33501 Bielefeld, Germany..
    Sluman, J.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Smirnov, O.
    Rhodes Univ, Dept Phys & Elelct, POB 94, ZA-6140 Grahamstown, South Africa.;SKA South Africa, 3rd Floor,The Pk,Pk Rd, ZA-7405 Pinelands, South Africa..
    Steinmetz, M.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Tagger, M.
    Univ Orleans CNRS, LPC2E, F-45071 Orleans, France..
    ter Veen, S.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    Thoudam, S.
    Radboud Univ Nijmegen, Dept Astrophys IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands..
    Toribio, M. C.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands.;Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands..
    Vermeulen, R.
    Netherlands Inst Radio Astron, ASTRON, Postbus 2, NL-7990 AA Dwingeloo, Netherlands..
    van Weeren, R. J.
    Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA..
    Wucknitz, O.
    Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany..
    Zarka, P.
    LESIA, Pl J Janssen, F-92195 Meudon, France.;PSL UPMC UPD SPC, CNRS, Observ Paris, USN, Pl J Janssen, F-92195 Meudon, France..
    The association of a J-burst with a solar jet2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 606, article id A81Article in journal (Refereed)
    Abstract [en]

    Context. The Sun is an active star that produces large-scale energetic events such as solar flares and coronal mass ejections, and numerous smaller scale events such as solar jets. These events are often associated with accelerated particles that can cause emission at radio wavelengths. The reconfiguration of the solar magnetic field in the corona is believed to be the cause of the majority of solar energetic events and accelerated particles. Aims. Here, we investigate a bright J-burst that was associated with a solar jet and the possible emission mechanism causing these two phenomena. Methods. We used data from the Solar Dynamics Observatory (SDO) to observe a solar jet and radio data from the Low Frequency Array (LOFAR) and the Nancay Radioheliograph (NRH) to observe a J-burst over a broad frequency range (33-173 MHz) on 9 July 2013 at similar to 11:06 UT. Results. The J-burst showed fundamental and harmonic components and was associated with a solar jet observed at extreme ultraviolet wavelengths with SDO. The solar jet occurred in the northern hemisphere at a time and location coincident with the radio burst and not inside a group of complex active regions in the southern hemisphere. The jet occurred in the negative polarity region of an area of bipolar plage. Newly emerged positive flux in this region appeared to be the trigger of the jet. Conclusions. Magnetic reconnection between the overlying coronal field lines and the newly emerged positive field lines is most likely the cause of the solar jet. Radio imaging provides a clear association between the jet and the J-burst, which shows the path of the accelerated electrons. These electrons travelled from a region in the vicinity of the solar jet along closed magnetic field lines up to the top of a closed magnetic loop at a height of similar to 360 Mm. Such small-scale complex eruptive events arising from magnetic reconnection could facilitate accelerated electrons to produce continuously the large numbers of Type III bursts observed at low frequencies, in a similar way to the J-burst analysed here.

  • 4. Morosan, D. E.
    et al.
    Gallagher, P. T.
    Zucca, P.
    Fallows, R.
    Carley, E. P.
    Mann, G.
    Bisi, M. M.
    Kerdraon, A.
    Konovalenko, A. A.
    MacKinnon, A. L.
    Rucker, H. O.
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Magdalenic, J.
    Vocks, C.
    Reid, H.
    Anderson, J.
    Asgekar, A.
    Avruch, O. M.
    Bentum, M. J.
    Bernardi, G.
    Best, P.
    Bonafede, A.
    Bregman, I.
    Breitling, F.
    Broderick, J.
    Brueggen, M.
    Butcher, H. R.
    Ciardi, B.
    Conway, J. E.
    de Gasperin, F.
    de Geus, E.
    Deller, A.
    Duscha, S.
    Eisloeffel, J.
    Engels, D.
    Falcke, H.
    Ferrari, C.
    Frieswijk, W.
    Garrett, M. A.
    Griessmeier, J.
    Gunst, A. W.
    Hassall, T. E.
    Hessels, J. W. T.
    Hoeft, M.
    Hoerandel, J.
    Horneffer, A.
    Iacobelli, M.
    Juette, E.
    Karastergiou, A.
    Kondratiev, V. I.
    Kramer, M.
    Kuniyoshi, M.
    Kuper, G.
    Maat, P.
    Markoff, S.
    McKean, J. P.
    Mulcahy, D. D.
    Munk, H.
    Nelles, A.
    Norden, M. J.
    Orru, E.
    Paas, H.
    Pandey-Pommier, M.
    Pandey, V. N.
    Pietka, G.
    Pizzo, R.
    Polatidis, A. G.
    Reich, W.
    Roettgering, H.
    Scaife, A. M. M.
    Schwarz, D.
    Serylak, M.
    Smirnov, O.
    Stappers, B. W.
    Stewart, A.
    Tagger, M.
    Tang, Y.
    Tasse, C.
    Thoudam, S.
    Toribio, C.
    Vermeulen, R.
    van Weeren, R. J.
    Wucknitz, O.
    Yatawatta, S.
    Zarka, P.
    LOFAR tied-array imaging of Type III solar radio bursts2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 568, p. A67-Article in journal (Refereed)
    Abstract [en]

    Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (< 100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio telescopes. Aims. Here, the combined high spatial, spectral, and temporal resolution of the LOw Frequency ARray (LOFAR) was used to study solar Type III radio bursts at 30-90 MHz and their association with CMEs. Methods. The Sun was imaged with 126 simultaneous tied-array beams within <= 5 R-circle dot of the solar centre. This method offers benefits over standard interferometric imaging since each beam produces high temporal (similar to 83 ms) and spectral resolution (12.5 kHz) dynamic spectra at an array of spatial locations centred on the Sun. LOFAR's standard interferometric output is currently limited to one image per second. Results. Over a period of 30 min, multiple Type III radio bursts were observed, a number of which were found to be located at high altitudes (similar to 4 R-circle dot from the solar center at 30 MHz) and to have non-radial trajectories. These bursts occurred at altitudes in excess of values predicted by 1D radial electron density models. The non-radial high altitude Type III bursts were found to be associated with the expanding flank of a CME. Conclusions. The CME may have compressed neighbouring streamer plasma producing larger electron densities at high altitudes, while the non-radial burst trajectories can be explained by the deflection of radial magnetic fields as the CME expanded in the low corona.

  • 5.
    Morosan, D. E.
    et al.
    Trinity Coll Dublin, Sch Phys, Dublin 2, Ireland..
    Gallagher, P. T.
    Trinity Coll Dublin, Sch Phys, Dublin 2, Ireland..
    Zucca, P.
    Trinity Coll Dublin, Sch Phys, Dublin 2, Ireland..
    O'Flannagain, A.
    Trinity Coll Dublin, Sch Phys, Dublin 2, Ireland..
    Fallows, R.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Reid, H.
    Univ Glasgow, SUPA, Sch Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland..
    Magdalenic, J.
    Royal Observ Belgium, SIDC, Solar Terr Ctr Excellence, B-1180 Brussels, Belgium..
    Mann, G.
    Leibniz Inst Astrophys Potsdam AIR, D-14482 Potsdam, Germany..
    Bisi, M. M.
    Harwell Oxford, RAE Space Sci & Technol Facil Council, Rutherford Appleton Lab, Oxford OX11 OQX, Oxon, England..
    Kerdraon, A.
    Observ Paris, LESIA, UMR 8109, CNRS, F-92195 Meudon, France..
    Konovalenko, A. A.
    Inst Radio Astron, UA-61002 Kharkov, Ukraine..
    MacKinnon, A. L.
    Univ Glasgow, SUPA, Sch Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland..
    Rucker, H. O.
    Austrian Acad Sci, Commiss Astron, A-8042 Graz, Austria..
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vocks, C.
    Leibniz Inst Astrophys Potsdam AIR, D-14482 Potsdam, Germany..
    Alexov, A.
    Space Telescope Sci Inst, Baltimore, MD 21218 USA..
    Anderson, J.
    Hehnholtz Zentrum Potsdam, DeutschesGeoForschunesZentrum GFZ, Dept Geodesy & Remote Sensing 1, D-14473 Potsdam, Germany..
    Asgekar, A.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Shell Technol Ctr, Bangalore 560099, Karnataka, India..
    Avruch, I. M.
    SRON Netherlands Inst Space Res, NL-9700 AV Groningen, Netherlands.;Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands..
    Bentum, M. J.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Univ Twente, NL-7522 NB Enxhede, Netherlands..
    Bernardi, G.
    Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA..
    Bonafede, A.
    Univ Hamburg, D-21029 Hamburg, Germany..
    Breitling, F.
    Leibniz Inst Astrophys Potsdam AIR, D-14482 Potsdam, Germany..
    Broderick, J. W.
    Univ Oxford, Astrophys, Oxford OX1 3RH, England.;Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England..
    Brouw, W. N.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands..
    Butcher, H. R.
    Australian Natl Univ, Res Sch Astron & Astrophys, Mt Stromlo Obs, Weston, ACT 2611, Australia..
    Ciardi, B.
    Max Planck Inst Astrophys, D-85741 Garching, Germany..
    de Geus, E.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;SmarterVision BV, NL-9401 JX Assen, Netherlands..
    Eisloeffel, J.
    Thnringer Landessternwarte, D-07778 Tautenburg, Germany..
    Falcke, H.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Radboud Univ Nijmegen, Dept Astrophys IMAPP, NL-6500 GL Nijmegen, Netherlands..
    Frieswijk, W.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Garrett, M. A.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Leiden Univ, Leiden Observ, NL-2300 RA Leiden, Netherlands..
    Griessmeier, J.
    Univ Orleans, CNRS, LPC2E, F-45071 Orleans 2, France.;Univ Orleans, Stn Radioastron Nancay, Observ Paris, CNRS,INSU,USR 704,OSUC, F-18330 Nancay, France..
    Gunst, A. W.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Hessels, J. W. T.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Univ Amsterdam, Anton Pannekoek Inst, NL-1090 GE Amsterdam, Netherlands..
    Hoeft, M.
    Thnringer Landessternwarte, D-07778 Tautenburg, Germany..
    Karastergiou, A.
    Univ Oxford, Astrophys, Oxford OX1 3RH, England..
    Kondratiev, V. I.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117997, Russia..
    Kuper, G.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    van Leeuwen, J.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Univ Amsterdam, Anton Pannekoek Inst, NL-1090 GE Amsterdam, Netherlands..
    McKay-Bukowski, D.
    Univ Oulu, Sodankyla Geophys Observ, Sodankyla 99600, Finland.;STFC Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England..
    McKean, J. P.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands.;Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands..
    Munk, H.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Orru, E.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Paas, H.
    Univ Groningen, CIT, NL-9700 CA Groningen, Netherlands..
    Pizzo, R.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Polatidis, A. G.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Scaife, A. M. M.
    Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England..
    Sluman, J.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Tasse, C.
    Observ Paris, LESIA, UMR 8109, CNRS, F-92195 Meudon, France..
    Toribio, M. C.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Vermeulen, R.
    Netherlands Inst Radio Astron, ASTRON, NL-7990 AA Dwingeloo, Netherlands..
    Zarka, P.
    Observ Paris, LESIA, UMR 8109, CNRS, F-92195 Meudon, France..
    LOFAR tied-array imaging and spectroscopy of solar S bursts2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 580, article id A65Article in journal (Refereed)
    Abstract [en]

    Context. The Sun is an active source of radio emission that is often associated with energetic phenomena ranging from nanoflares to coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), numerous millisecond duration radio bursts have been reported, such as radio spikes or solar S bursts (where S stands for short). To date, these have neither been studied extensively nor imaged because of the instrumental limitations of previous radio telescopes. Aims. Here, LOw Frequency ARray (LOFAR) observations were used to study the spectral and spatial characteristics of a multitude of S bursts, as well as their origin and possible emission mechanisms. Methods. We used 170 simultaneous tied-array beams for spectroscopy and imaging of S bursts. Since S bursts have short timescales and fine frequency structures, high cadence (similar to 50 ms) tied-array images were used instead of standard interferometric imaging, that is currently limited to one image per second. Results. On 9 July 2013, over 3000 S bursts were observed over a time period of similar to 8 h. S bursts were found to appear as groups of short-lived (<1 s) and narrow-bandwidth (similar to 2.5 MHz) features, the majority drifting at similar to 3.5 MHz s(-1) and a wide range of circular polarisation degrees (2-8 times more polarised than the accompanying Type III bursts). Extrapolation of the photospheric magnetic field using the potential field source surface (PFSS) model suggests that S bursts are associated with a trans-equatorial loop system that connects an active region in the southern hemisphere to a bipolar region of plage in the northern hemisphere. Conclusions. We have identified polarised, short-lived solar radio bursts that have never been imaged before. They are observed at a height and frequency range where plasma emission is the dominant emission mechanism, however, they possess some of the characteristics of electron-cyclotron maser emission.

  • 6.
    Oldoni, Matteo
    et al.
    SIAE Microelettron, R&D Dept, IT-20093 Cologno Monzese, MI, Italy..
    Spinello, Fabio
    Univ Padua, Dept Informat Engn, IT-35131 Padua, Italy.;TwistOff SRL, IT-35129 Padua, Italy..
    Mari, Elettra
    TwistOff SRL, IT-35129 Padua, Italy..
    Parisi, Giuseppe
    TwistOff SRL, IT-35129 Padua, Italy..
    Someda, Carlo Giacomo
    TwistOff SRL, IT-35129 Padua, Italy..
    Tamburini, Fabrizio
    TwistOff SRL, IT-35129 Padua, Italy..
    Romanato, Filippo
    Univ Padua, Dept Phys & Astron G Galilei, IT-35131 Padua, Italy..
    Ravanelli, Roberto Antonio
    SIAE Microelettron, R&D Dept, IT-20093 Cologno Monzese, MI, Italy..
    Coassini, Piero
    SIAE Microelettron, R&D Dept, IT-20093 Cologno Monzese, MI, Italy..
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Space-Division Demultiplexing in Orbital-Angular-Momentum-Based MIMO Radio Systems2015In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 63, no 10, p. 4582-4587Article in journal (Refereed)
    Abstract [en]

    Radio beams that carry nonzero orbital angular momentum (OAM) are analyzed from the viewpoint of a multiple-input-multiple-output (MIMO) communication system. Often, the natural OAM-beam orthogonality cannot be fully exploited because of spatial constraints on the receiving antenna size. Therefore, we investigate how far OAM-induced phase variations can be exploited in spatial demultiplexing based on conventional (linear momentum) receivers. Performances are investigated versus position and size of the transmitting and receiving devices. The use of OAM-mode coherent superpositions is also considered, in view of recent work by Edfors et al. Our final goal is to assess the merits of an OAM-based MIMO system, in comparison with a conventional one.

  • 7.
    Risch, Tore
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science. Datalogi.
    Ivanova, Milena
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science. Datalogi.
    Thide, Bo
    Department of Medical Pharmacology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science.
    High-performance GRID Database Manager for Scientific Data2002In: Workshop on Distributed Data & Structures - WDAS-2002, Paris, France, 2002Conference paper (Refereed)
  • 8.
    Risch, Tore
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science. Datalogi.
    Stefansson, H
    Thide, Bo
    Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science.
    PLOT, ett datorprogram för kurvritning1979Report (Other scientific)
  • 9.
    Stål, Oscar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Bergman, Jan E.S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Daldorff, Lars K.S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ingelman, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics.
    Prospects for Lunar Satellite Detection of Radio Pulses from Ultrahigh Energy Neutrinos Interacting with the Moon2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 7, p. 071103-Article in journal (Refereed)
    Abstract [en]

    The Moon provides a huge effective detector volume for ultrahigh energy cosmic neutrinos, which generate coherent radio pulses in the lunar surface layer due to the Askaryan effect. We report systematic Monte Carlo simulations which show that radio instruments on board a Moon-orbiting satellite can detect Askaryan pulses from neutrinos with energies above 10^{19} eV, i.e. near and above the interesting GZK limit, at the very low fluxes predicted in different scenarios.

  • 10. Stål, Oscar
    et al.
    Bergman, Jan
    Thide, Bo
    Ahlen, L
    Ingelman, Gunnar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Nuclear and Particle Physics. Högenergifysik.
    Lunar Satellite Detection of Ultra-High Energy Neutrinos with the Use of Radio Methods2005In: DGLR Interational Symposium: To Moon and Beyond, Bremen, Germany, 15-16 Sep 2005., 2005Conference paper (Refereed)
    Abstract [en]

    Neutrinos interact with matter only through weak processes with low cross-section. To detect cosmic neutrinos most efforts have relied on the detection of visible Vavilov-Cerenkov light in detectors embedded in the target volumes. To access the decreasing flux of ultra-high energy neutrinos, far above 1 PeV, ideas on how to increase the detection volume by observing coherent radio frequency emission caused by the Askaryan effect have been put forward. Here we describe how a satellite in lunar orbit equipped with an electromagnetic vector sensor could detect Askaryan pulses induced by neutrinos interacting with the moon. The threshold neutrino energy is found to be 50 EeV for this setup, and the sensitivity is determined from simulations. A model dependent event rate of 2.2 events per year is calculated.

  • 11.
    Tamburini, F.
    et al.
    Twistoff SRL, Padua, Italy.;Univ Padua, Dept Phys & Astron, Padua, Italy..
    Mari, E.
    Twistoff SRL, Padua, Italy.;Univ Padua, Dept Phys & Astron, Padua, Italy..
    Parisi, G.
    Twistoff SRL, Padua, Italy..
    Spinello, F.
    Twistoff SRL, Padua, Italy.;Univ Padua, Dept Informat Engn, Padua, Italy..
    Oldoni, M.
    SIAE Microelettron, Cologno Monzese, Italy..
    Ravanelli, R. A.
    SIAE Microelettron, Cologno Monzese, Italy..
    Coassini, P.
    SIAE Microelettron, Cologno Monzese, Italy..
    Someda, C. G.
    Twistoff SRL, Padua, Italy..
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Romanato, F.
    Twistoff SRL, Padua, Italy.;Univ Padua, Dept Phys & Astron, Padua, Italy..
    Tripling the capacity of a point-to-point radio link by using electromagnetic vortices2015In: Radio Science, ISSN 0048-6604, E-ISSN 1944-799X, Vol. 50, no 6, p. 501-508Article in journal (Refereed)
    Abstract [en]

    In this paper we report the results from outdoor experiments showing that it is possible to increase the data transmission capacity using at least three coherent, orthogonal beams on the same frequency, 17.128GHz, each in a unique orbital angular momentum state. Each beam was encoded with the digital modulations used in present-day telecommunications. We achieved an error-free throughput of 3x11Mbit/s with four-Quadrature Amplitude Modulation over a 7MHz bandwidth over 100m and 150m long links.

  • 12. Tamburini, F.
    et al.
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Storming Majorana's Tower with OAM states of light in a plasma2011In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 96, no 6, p. 64005-Article in journal (Refereed)
    Abstract [en]

    We extend the relationship between mass and spin angular momentum, described by the bosonic spectrum of positive definite mass particles of the Majorana solution to the Dirac equation, to photons that acquire an effective Proca mass through the Anderson-Higgs mechanism (Anderson P. W., Phys. Rev., 130 (1963) 439) when they propagate in a plasma. In an earlier paper (TAMBURINI F. et al., EPL, 90 (2010) 45001) we showed that if the plasma is structured, it can impart orbital angular momentum (OAM) to the photons that reduces the total Proca photon mass. Here we show, through a generalisation of Majorana's solution, that photons with OAM in a plasma cannot assume negative squared mass states. This means that there exist interesting analogies with Quantum Gravity or General Relativity models involving a modified action of the Lorentz group.

  • 13. Tamburini, F.
    et al.
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Mari, E.
    Sponselli, A.
    Bianchini, A.
    Romanato, F.
    Reply to Comment on 'Encoding many channels on the same frequency through radio vorticity: first experimental test'2012In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 14, p. 118002-Article in journal (Other academic)
    Abstract [en]

    Our recent paper (Tamburini et al 2012 New J. Phys. 14 033001), which presented results from outdoor experiments that demonstrate that it is physically feasible to simultaneously transmit different states of the newly recognized electromagnetic (EM) quantity orbital angular momentum (OAM) at radio frequencies into the far zone and to identify these states there, has led to a comment (Tamagnone et al 2012 New J. Phys. 14 118001). These authors discuss whether our investigations can be regarded as a particular implementation of the multiple-input-multiple-output (MIMO) technique. Clearly, our experimental confirmation of a theoretical prediction, first made almost a century ago (Abraham 1914 Phys. Z. XV 914-8), that the total EM angular momentum (a pseudovector of dimension length x mass x velocity) can propagate over huge distances, is essentially different from-and conceptually incompatible with-the fact that there exist engineering techniques that can enhance the spectral capacity of EM linear momentum (an ordinary vector of dimension mass x velocity). Our OAM experiments (Tamburini et al 2012 New J. Phys. 14 033001; Tamburini et al 2011 Appl. Phys. Lett. 99 204102-3) confirm the availability of a new physical layer for real-world radio communications based on EM rotational degrees of freedom. The next step is to develop new protocols and techniques for high spectral density on this new physical layer. This includes MIMO-like and other, more efficient, techniques.

  • 14.
    Tamburini, Fabrizio
    et al.
    ZKM, Lorentzstr 19, D-76135 Karlsruhe, Germany.;MSC BW, Nobelstr 19, D-70550 Stuttgart, Germany..
    De laurentis, Mariafelicia
    Goethe Univ, Inst Theoret Phys, Max von Laue Str 1, D-60438 Frankfurt, Germany.;Tomsk State Pedag Univ, Ul Kievskaya 60, Tomsk 634061, Russia.;Tomsk State Univ Control Syst & Radioelectron TUS, Lab Theoret Cosmol, Tomsk 634050, Russia.;INFN, Sez Napoli, Compl Univ Monte S Angelo,Edificio G,Via Cinthia, I-80126 Naples, Italy..
    Licata, Ignazio
    Inst Sci Methodol ISEM, I-90146 Palermo, Italy.;Sch Adv Int Studies Theoret & Nonlinear Methodol, I-70124 Bari, Italy.;BM Birla Sci Ctr, IIAMIS, Hyderabad 500463, Andhra Pradesh, India..
    Thide, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Twisted Soft Photon Hair Implants on Black Holes2017In: Entropy, ISSN 1099-4300, E-ISSN 1099-4300, Vol. 19, no 9, article id 458Article in journal (Refereed)
    Abstract [en]

    Background: The Hawking-Perry-Strominger (HPS) work states a new controversial idea about the black hole (BH) information paradox, where BHs maximally entropize and encode information in their event horizon area, with no "hair" thought to reveal information outside but angular momentum, mass, and electric charge only in a unique quantum gravity (QG) vacuum state. New conservation laws of gravitation and electromagnetism, appear to generate different QG vacua, preserving more information in soft photon/graviton hair implants. We find that BH photon hair implants can encode orbital angular momentum (OAM) and vorticity of the electromagnetic (EM) field. Methods: Numerical simulations are used to plot an EM field with OAM emitted by a set of dipolar currents together with the soft photon field they induce. The analytical results confirm that the soft photon hair implant carries OAM and vorticity. Results: a set of charges and currents generating real EM fields with precise values of OAM induce a "curly", twisted, soft-hair implant on the BH with vorticity and OAM increased by one unit with respect to the initial real field. Conclusions: Soft photon implants can be spatially shaped ad hoc, encoding structured and densely organized information on the event horizon.

  • 15. Tamburini, Fabrizio
    et al.
    Mari, Elettra
    Sponselli, Anna
    Thide, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Bianchini, Antonio
    Romanato, Filippo
    Encoding many channels on the same frequency through radio vorticity: first experimental test2012In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 14, p. 033001-Article in journal (Refereed)
    Abstract [en]

    We have shown experimentally, in a real-world setting, that it is possible to use two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, to simultaneously transmit two independent radio channels. This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques. This paves the way for innovative techniques in radio science and entirely new paradigms in radio communication protocols that might offer a solution to the problem of radio-band congestion.

  • 16. Tamburini, Fabrizio
    et al.
    Mari, Elettra
    Thide, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Barbieri, Cesare
    Romanato, Filippo
    Experimental verification of photon angular momentum and vorticity with radio techniques2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, no 20, p. 204102-Article in journal (Refereed)
    Abstract [en]

    The experimental evidence that radio techniques can be used for synthesizing and analyzing non-integer electromagnetic (EM) orbital angular momentum (OAM) of radiation is presented. The technique used amounts to sample, in space and time, the EM field vectors and digitally processing the data to calculate the vortex structure, the spatial phase distribution, and the OAM spectrum of the radiation. The experimental verification that OAM-carrying beams can be readily generated and exploited by using radio techniques paves the way to an entirely new paradigm of radar and radio communication protocols.

  • 17.
    Thide, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Tamburini, F.
    Then, H.
    Someda, C. G.
    Mari, E.
    Parisi, G.
    Spinello, F.
    Romanato, F.
    Angular Momentum Radio2014In: Complex Light and Optical Forces VIII / [ed] David L. Andrews, Enrique J. Galvez and Jesper Glückstad, 2014, Vol. 8999, p. 89990B-Conference paper (Refereed)
    Abstract [en]

    Wireless communication amounts to encoding information onto physical observables carried by electromagnetic (EM) fields, radiating them into surrounding space, and detecting them remotely by an appropriate sensor connected to an information-decoding receiver. Each observable is second order in the fields and fulfills a conservation law. In present-day radio only the EM linear momentum observable is fully exploited. A fundamental physical limitation of this observable, which represents the translational degrees of freedom of the charges (typically an oscillating current along a linear antenna) and the fields, is that it is single-mode. This means that a linear-momentum radio communication link comprising one transmitting and one receiving antenna, known as a single-input-single-output (SISO) link, can provide only one transmission channel per frequency (and polarization). In contrast, angular momentum, which represents the rotational degrees of freedom, is multi-mode, allowing an angular-momentum SISO link to accommodate an arbitrary number of independent transmission channels on one and the same frequency (and polarization). We describe the physical properties of EM angular momentum and how they can be exploited, discuss real-world experiments, and outline how the capacity of angular momentum links may be further enhanced by employing multi-port techniques, i.e., the angular momentum counterpart of linear-momentum multiple-input-multiple-output (MIMO).

  • 18.
    Thidé, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Tamburini, Fabrizio
    Twist Off SRL, Padua, Italy..
    Angular Momentum Radio Techniques2015In: 2015 1st URSI Atlantic Radio Science Conference (URSI AT-RASC), 2015Conference paper (Refereed)
  • 19.
    Thidé, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Tamburini, Fabrizio
    Twist SRL, Padua, Italy..
    The Physics of Angular Momentum Radio2015In: 2015 1st URSI Atlantic Radio Science Conference (URSI AT-RASC), 2015Conference paper (Refereed)
1 - 19 of 19
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