Measurement of cosmic rays with LOFAR

14th International Conference on Topics in Astroparticle and Underground Physics

物理学;天文学

Rossetto, L.^1 ; Buitink, S.^2 ; Corstanje, A.^1 ; Enriquez, J.E.^1 ; Falcke, H.^1,3,4 ; Hörandel, J.R.^1,3 ; Nelles, A.^5 ; Rachen, J.P.^1 ; Schellart, P.^1 ; Scholten, O.^6,7 ; Ter Veen, S.^1,4 ; Thoudam, S.^8 ; Trinh, T.N.G.^6

Department of Astrophysics, IMAPP, Radboud University Nijmegen, P.O. Box 9010, Nijmegen

6500 GL, Netherlands^1

Astrophysical Institute, Vrije Universiteit Brussel, Pleinlaan 2, Brussels

1050, Belgium^2

NIKHEF, Science Park Amsterdam, Amsterdam

1098 XG, Netherlands^3

Netherlands Institute of Radio Astronomy (ASTRON), Postbus 2, Dwingeloo

7990 AA, Netherlands^4

Department of Physics and Astronomy, University of California Irvine, Irvine

CA

92697-4575, United States^5

KVI-CART, University Groningen, P.O. Box 72, Groningen

9700 AB, Netherlands^6

Interuniversity Institute for High-Energy, Vrije Universiteit Brussel, Pleinlaan 2, Brussels

1050, Belgium^7

Department of Physics and Electrical Engineering, Linnéuniversitetet, Växjö

35195, Sweden^8

关键词: Curved wavefronts;    Earth magnetic fields;    Extensive air showers;    Frequency ranges;    Gaussian functions;    Mass composition;    Reconstruction techniques;    Two-dimensional patterns;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/718/5/052035/pdf
DOI  :  10.1088/1742-6596/718/5/052035

学科分类：天文学(综合)

来源: IOP

【 摘 要 】

The LOw Frequency ARay (LOFAR) is a multipurpose radio-antenna array aimed to detect radio signals in the 10 - 240 MHz frequency range, covering a large surface in Northern Europe with a higher density in the Northern Netherlands. Radio emission in the atmosphere is produced by cosmic-ray induced air showers through the interaction of charged particles with the Earth magnetic field. The detection of radio signals allows to reconstruct several properties of the observed cascade. We review here all important results achieved in the last years. We proved that the radio-signal distribution at ground level is described by a two-dimensional pattern, which is well fitted by a double Gaussian function. The radio-signal arrival time and polarization have been measured, thus providing additional information on the extensive air shower geometry, and on the radio emission processes. We also showed that the radio signal reaches ground in a thin, curved wavefront which is best parametrized by a hyperboloid shape centred around the shower axis. Radio emission has also been studied under thunderstorm conditions and compared to fair weather conditions. Moreover, by using a hybrid reconstruction technique, we performed mass composition measurements in the energy range 1017- 1018eV.