cosmic ray air shower and its radio detection - 国家天文台.ppt

The Cosmic Ray Air Shower and its Radio Detection 陈学雷 国家天文台 Cosmic Ray Energy Spectrum Origin of Cosmic Ray Puzzle of Ultra High Energy Cosmic Ray: the GZK cutoff Possible solutions GZK or not? Detection of air showers Radio Signal Coherent Emission: Radio Pulse Signal Strength Spectrum distribution and polarization Energy Dependence Background Noise LOPES LOPES 10 Results CODALEMA experiment Results Radio Detection in China Road Map prototype proposal Preliminary Design Simulated detection rate Site Selection Plan * EAS Exp. The maximum energy observed so far is about 3.2x1020eV eq. 50 J Many discoveries in particle physics: positron, muon, pion, Kaon, ... Now: astrophysical side Fermi acceleration Propagation of Cosmic Ray charged particle moving in random magnetic field E 1015 eV, confined around galaxy (some diffuse out) Greisen 1966, Zatsepin Kuzmin 1966 Incorrect measurement? Heavy nuclei? produced nearby: superheavvy dark matter? topological defects? produced nearyby: strong IGM magnetic field? produced far away: neutrino? produced far away: break down of relativity (violation of Lorentz invariance)? Ground Array: small area emulsion, scintillator, water Cherenkov Optical: low duty cycle atmosphere Cherenkov Fluorescence radio: large area, high duty cycle Geosynchrotron (Kahn Lerche 1966) charge seperation by geomagnetic field Negative charge excess in EAS and radio signal (Askayran 1962): production of delta-ray (knocked out electrons) annihilation of positron in flight First detection (Jelley et al 1965) Review (Allan 1971), loss of interest Revival (Falcke Gorham 2002) CASA-MIA, LOPES/LOFAR, CODALEMA EM wave ~ apparant acceleration of electric charge Radio pulse for a 1017 eV shower, at 0, 100,250 m from axis (Huege Falcke astro-ph/0309622) Allan’s formula: Monte Carlo Simulation by Huege Falcke, astro-ph/0501580, at 20m, 140m, 260m, 380m, 500m total EW pol