Calibration of the LOFAR low-band antennas using the Galaxy and a model of the signal chain

Abstract

The LOw-Frequency ARray (LOFAR) is used to make precise measurements of radio emission from extensive air showers, yielding information about the primary cosmic ray. Interpreting the measured data requires an absolute and frequency-dependent calibration of the LOFAR system response. This is particularly important for spectral analyses, because the shape of the detected signal holds information about the shower development. We revisit the calibration of the LOFAR antennas in the range of 30 - 80 MHz. Using the Galactic emission and a detailed model of the LOFAR signal chain, we find an improved calibration that provides an absolute energy scale and allows for the study of frequency-dependent features in measured signals. With the new calibration, systematic uncertainties of 13% are reached, and comparisons of the spectral shape of calibrated data with simulations show promising agreement.

arXiv comment23 pages, 10 figures

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Cited by in corpus (9)

• Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers
• Depth of shower maximum and mass composition of cosmic rays from 50 PeV to 2 EeV measured with the LOFAR radio telescope
• Radio emission from negative lightning leader steps reveals inner meter-scale structure
• Reconstructing air shower parameters with LOFAR using event specific GDAS atmospheres
• The initial stage of cloud lightning imaged in high-resolution
• Time resolved 3Dinterferometric imaging of a section of a negative leader with LOFAR
• On the cosmic-ray energy scale of the LOFAR radio telescope
• Uncertainties of the 30-408 MHz Galactic emission as a calibration source for radio detectors in astroparticle physics
• A Bayesian Method for Air-Shower Reconstruction using Information Field Theory