The lateral distribution function (LDF) for coherent electromagnetic radiation from air showers initiated by ultra-high-energy cosmic rays is calculated using a macroscopic description. A new ...expression is derived to calculate the coherent radio pulse at small distances from the observer. It is shown that for small distances to the shower axis the shape of the electric pulse is determined by the ‘pancake’ function, describing the longitudinal distribution of charged particles within the shower front, while for large distances the pulse is determined by the shower profile. This reflects in a different scaling of the LDF at small and at large distances. As a first application we calculate the LDF for proton- and iron-induced showers and we show that this offers a very sensitive measure to discriminate between these two. We show that due to interference between the geo-magnetic and the charge-excess contributions the intensity pattern of the radiation is not circular symmetric.
The Giant Radio Array for Neutrino Detection Martineau-Huynh, Olivier; Kotera, Kumiko; Bustamente, Mauricio ...
EPJ Web of Conferences,
01/2016, Letnik:
116
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
High-energy neutrino astronomy will probe the working of the most violent phenomena in the Universe. The Giant Radio Array for Neutrino Detection (GRAND) project consists of an array of ∼ 105 radio ...antennas deployed over ∼ 200 000 km2 in a mountainous site. It aims at detecting high-energy neutrinos via the measurement of air showers induced by the decay in the atmosphere of τ leptons produced by the interaction of cosmic neutrinos under the Earth surface. Our objective with GRAND is to reach a neutrino sensitivity of 5 × 10−11E−2 GeV−1 cm−2 s−1 sr−1 above 3 × 1016 eV. This sensitivity ensures the detection of cosmogenic neutrinos in the most pessimistic source models, and up to 100 events per year are expected for the standard models. GRAND would also probe the neutrino signals produced at the potential sources of UHECRs.
The Giant Radio Array for Neutrino Detection Martineau-Huynh, Olivier; Bustamante, Mauricio; Carvalho, Washington ...
EPJ Web of Conferences,
01/2017, Letnik:
135
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The Giant Radio Array for Neutrino Detection (GRAND) is a planned array of ~ 2·105 radio antennas deployed over ~ 200 000 km2 in a mountainous site. It aims primarly at detecting high-energy ...neutrinos via the observation of extensive air showers induced by the decay in the atmosphere of taus produced by the interaction of cosmic neutrinos under the Earth surface. GRAND aims at reaching a neutrino sensitivity of 5 · 10−11 E−2 GeV−1 cm−2 s−1 sr−1 above 3 · 1016 eV. This ensures the detection of cosmogenic neutrinos in the most pessimistic source models, and ~50 events per year are expected for the standard models. The instrument will also detect UHECRs and possibly FRBs. Here we show how our preliminary design should enable us to reach our sensitivity goals, and discuss the steps to be taken to achieve GRAND, while the compelling science case for GRAND is discussed in more details in 1.
MGMR3D is a code that calculates the complete radio footprint, i.e. intensity, polarization and pulse shapes, for a parametrized shower current density using a semianalytic approach. The ...non-Monte-Carlo code is fast (typically 10 seconds for a complete footprint) and thus can be used in a chi-square optimization calculation of atmospheric electric fields or to optimize antenna geometry.
We have developed a code that semi-analytically calculates the radio footprint (intensity and polarization) of an extensive air shower subject to atmospheric electric fields. This can be used to ...reconstruct the height dependence of atmospheric electric field from the measured radio footprint. The various parameterizations of the spatial extent of the induced currents are based on the results of Monte-Carlo shower simulations. The calculated radio footprints agree well with microscopic CoREAS simulations.
We discuss the radar detection method as a probe for high-energy neutrino induced particle cascades in ice. In a previous work we showed that the radar detection techniqe is a promising method to ...probe the high-energy cosmic neutrino flux above PeV energies. This was done by considering a simplified cascade geometry and scattering model. In this article we discuss the scattering in more detail. We provide a model for the radar cross-section based on the induced plasma properties, and discuss the angular dependence of the scatter.
We discuss the radio emission from a cosmic-ray air shower propagating in air before it hits an air-ice boundary after which it completes its propagation inside the ice. The in-air emission, the ...in-ice emission, as well as the transition radiation from the shower crossing the boundary is considered. We discuss the interpretation of the radio signal observed by an in-ice observer.
The physics of radio emission from cosmic-ray induced air showers Is shortly summarized. It will be shown that the radio signal at different distances from the shower axis provides complementary ...Information on the longitudinal shower evolution, In particular the early part, and on the distribution of the electrons In the shower core. This complements the information obtained from surface, fluorescence, and muon detectors and Is very useful In getting a comprehensive picture of an air shower.
Autonomous radio-detection, i.e., detection of air-showers with standalone radio arrays, is one of the major technical challenges to overcome for the next generation astroparticle detectors. In this ...context, we study polarisation signatures of simulated radio signals to perform an identification of the associated air-showers initiated by cosmic-rays and neutrinos. We compare the two sources of radio emission (the charge excess and geomagnetic) and show that the former is almost negligible for inclined (zenith angle >65°) cosmic-ray air-showers. This provides an efficient background rejection criterion at the DAQ level, based on the projection of the total electric field along the direction of the local magnetic field. This relevant quantity can be computed, — even in an online treatment — for antennas measuring three orthogonal polarisations. Independently of the experimental antenna layout, we estimate that assuming a random polarisation of noise events, a rejection from ≈72% (for a non favourable detector location) to ≈93% (for a favourable one) of the noise induced events and a trigger efficiency of 86% (93%) with a 3σ (5σ) trigger threshold level should be achievable. We also show that neutrino-induced showers present a charge excess to geomagnetic signal ratio up to ∼10 times higher than for cosmic ray showers. Although this characteristic makes the identification of neutrino-induced showers challenging via the method developed here, it provides an efficient criterion to perform an offline discrimination between cosmic-ray and neutrino primaries. The stronger charge excess emission will also help the reconstruction of air-shower parameters, such as the core position.
An ultra-high-energy cosmic ray (UHECR) colliding with the Earth's atmosphere gives rise to an Extensive Air Shower (EAS). Due to different charge separation mechanisms within the thin shower front ...coherent electromagnetic radiation will be emitted within the radio frequency range. A small deviation of the index of refraction from unity will give rise to Cherenkov radiation up to distances of 100
m from the shower core and therefore has to be included in a complete description of the radio emission from an EAS. Interference between the different radiation mechanisms, in combination with different polarization behavior will reflect in a lateral distribution function (LDF) depending on the orientation of the observer and a non-trivial fall-off of the radio signal as function of distance to the shower core.
PDF
