Radio Pulse Production in Extensive Air Showers

Allan, H. R.; Clay, R. W.; Jones, James; Abrosimov, A.T.; Neat, K. P.

doi:10.1038/222635a0

Cited by 22 publications

(11 citation statements)

References 18 publications

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“…A dependence of the polarisation of the emitted radiation on the earth's magnetic field direction was also confirmed by a number of experiments (e.g., Allan et al 1969), supporting the case for the geomagnetic emission mechanism. The actual strength of the emission, however, is still largely unknown at present state.…”

Section: Comparison With Experimental Datamentioning

confidence: 50%

“…While the former is dominant in case of dense media (Buniy & Ralston 2002;Zas et al 1992;Alvarez-Muñiz et al 2000), polarisation measurements in a number of experiments subsequently supported the dominance of the geomagnetic emission mechanism for radio emission from EAS in air (e.g., Allan et al 1969). It also seems unavoidable in principle for highly relativistic charged particles moving in the earth's magnetic field.…”

Section: The Geosynchrotron Approachmentioning

confidence: 94%

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Radio emission from cosmic ray air showers

Huege¹,

Falcke

2003

A&A

144

154

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Abstract. Cosmic ray air showers have been known for over 30 years to emit pulsed radio emission in the frequency range from a few to a few hundred MHz, an effect that offers great opportunities for the study of extensive air showers with upcoming fully digital "software radio telescopes" such as LOFAR and the enhancement of particle detector arrays such as KASCADE Grande or the Pierre Auger Observatory. However, there are still a lot of open questions regarding the strength of the emission as well as the underlying emission mechanism. Accompanying the development of a LOFAR prototype station dedicated to the observation of radio emission from extensive air showers, LOPES, we therefore take a new approach to modeling the emission process, interpreting it as "coherent geosynchrotron emission" from electron-positron pairs gyrating in the earth's magnetic field. We develop our model in a step-by-step procedure incorporating increasingly realistic shower geometries in order to disentangle the coherence effects arising from the different scales present in the air shower structure and assess their influence on the spectrum and radial dependence of the emitted radiation. We infer that the air shower "pancake" thickness directly limits the frequency range of the emitted radiation, while the radial dependence of the emission is mainly governed by the intrinsic beaming cone of the synchrotron radiation and the superposition of the emission over the air shower evolution as a whole. Our model succeeds in reproducing the qualitative trends in the emission spectrum and radial dependence that were observed in the past, and is consistent with the absolute level of the emission within the relatively large systematic errors in the experimental data.

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Section: Comparison With Experimental Datamentioning

confidence: 50%

Section: The Geosynchrotron Approachmentioning

confidence: 94%

Radio emission from cosmic ray air showers

Huege¹,

Falcke

2003

A&A

144

154

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“…First, the geomagnetic mechanism generates beamed synchrotron emission through relativistic electronpositron pairs in the Earth's magnetic field, which is believed to be the dominant mechanism (Allan et al 1967;Allan et al 1969). This ansatz led to the description of coherent geosynchrotron emission at meter wavelengths (Falcke & Gorham 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Those early studies found strongly pulsed radio emission from air showers detected with radio antennae triggered by particle detectors. A dependence of the radio emission's polarization on the geomagnetic field favored a geomagnetic emission mechanism (see, e.g., Allan et al 1967Allan et al , 1969Sun 1975). The first quantitative radio frequency spectra were obtained from a few simultaneous narrowband observations below 100 MHz by, e.g., Spencer (1969), Allan et al (1970), andPrah (1971).…”

Section: Introductionmentioning

confidence: 99%

Frequency spectra of cosmic ray air shower radio emission measured with LOPES

Nigl

Apel²,

Arteaga

et al. 2008

A&A

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Aims. We wish to study the spectral dependence of the radio emission from cosmic-ray air showers around 100 PeV (10 17 eV). Methods. We observe short radio pulses in a broad frequency band with the dipole-interferometer LOPES (LOFAR Prototype Station), which is triggered by a particle detector array named Karlsruhe Shower Core and Array Detector (KASCADE). LOFAR is the Low Frequency Array. For this analysis, 23 strong air shower events are selected using parameters from KASCADE. The radio data are digitally beam-formed before the spectra are determined by sub-band filtering and fast Fourier transformation. Results. The resulting electric field spectra fall off to higher frequencies. An average electric field spectrum is fitted with an exponential E ν = K · exp (ν/MHz/β) and β = −0.017 ± 0.004, or alternatively, with a power law ν = K · ν α and a spectral index of α = −1 ± 0.2. The spectral slope obtained is not consistent within uncertainties and it is slightly steeper than the slope obtained from Monte Carlo simulations based on air showers simulated with CORSIKA (Cosmic Ray Simulations for KASCADE). For the analyzed sample of LOPES events, we do not find any significant dependence of the spectral slope on the electric field amplitude, the azimuth angle, the zenith angle, the curvature radius, nor on the average distance of the antennae from the shower core position. But one of the strongest events was measured during thunderstorm activity in the vicinity of LOPES and shows the longest pulse length measured of 110 ns and a spectral slope of α = −3.6. Conclusions. We show with two different methods that frequency spectra from air shower radio emission can be reconstructed on event-by-event basis, with only two dozen dipole antennae simultaneously over a broad range of frequencies. According to the obtained spectral slopes, the maximum power is emitted below 40 MHz. Furthermore, the decrease in power to higher frequencies indicates a loss in coherence determined by the shower disc thickness. We conclude that a broader bandwidth, larger collecting area, and longer baselines, as will be provided by LOFAR, are necessary to further investigate the relation of the coherence, pulse length, and spectral slope of cosmic ray air showers.

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“…After first being discovered in the late 1960s [1], radio emission of air showers has again received increasing interest in the past years. This is mainly due to the achievements in information technology, which open the possibility to use phased arrays of radio antennas in combination with digital beamforming.…”

Section: Motivationmentioning

confidence: 99%

A Radio Air-Shower Test Array (RASTA) for IceCube

Böser

2012

Nuclear Instruments and Methods in Physics Research Section A:

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In this paper we explore the possibility to complement the cosmic ray physics program of the IceCube observatory with an extended surface array of radio antennas. The combination of air-shower sampling on the surface and muon calorimetry underground offers significant scientific potential: the neutrino sensitivity above the horizon can be enhanced by vetoing air-showers on the ground, photon-induced air-showers can be identified by their small muon component and the coincident measurement of the particle density on the surface and the muon component gives useful information on the composition of the primary flux.All of these analyses are pursued with the existing IceTop array. However, the IceTop footprint is small compared to the acceptance of the InIce sensor array, which severely limits the solid angle for coincident measurements, calling for an extended surface air-shower detector. As demonstrated by the LOPES experiment, measuring air-showers through their geosynchrotron emission has become a viable and cost-efficient method. The science case for the RASTA project -a dedicated radio array seeking to exploit this method at the South Pole -is presented.

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Radio Pulse Production in Extensive Air Showers

Cited by 22 publications

References 18 publications

Radio emission from cosmic ray air showers

Radio emission from cosmic ray air showers

Frequency spectra of cosmic ray air shower radio emission measured with LOPES

A Radio Air-Shower Test Array (RASTA) for IceCube

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