161 research outputs found
Modelling uncertainty of the radiation energy emitted by extensive air showers
Recently, the energy determination of extensive air showers using radio
emission has been shown to be both precise and accurate. In particular, radio
detection offers the opportunity for an independent measurement of the absolute
energy of cosmic rays, since the radiation energy (the energy radiated in the
form of radio signals) can be predicted using first-principle calculations
involving no free parameters, and the measurement of radio waves is not subject
to any significant absorption or scattering in the atmosphere. Here, we verify
the implementation of radiation-energy calculations from microscopic simulation
codes by comparing Monte Carlo simulations made with the two codes CoREAS and
ZHAireS. To isolate potential differences in the radio-emission calculation
from differences in the air-shower simulation, the simulations are performed
with equivalent settings, especially the same model for the hadronic
interactions and the description of the atmosphere. Comparing a large set of
simulations with different primary energies and shower directions we observe
differences amounting to a total of only 3.3 %. This corresponds to an
uncertainty of only 1.6 % in the determination of the absolute energy scale and
thus opens the potential of using the radiation energy as an accurate
calibration method for cosmic ray experiments.Comment: 8 pages, 2 figures, ICRC2017 contributio
Determination of the absolute energy scale of extensive air showers via radio emission: systematic uncertainty of underlying first-principle calculations
Recently, the energy determination of extensive air showers using radio
emission has been shown to be both precise and accurate. In particular, radio
detection offers the opportunity for an independent measurement of the absolute
energy scale of cosmic rays, since the radiation energy (the energy radiated in
the form of radio signals) can be predicted using first-principle calculations
involving no free parameters, and the measurement of radio waves is not subject
to any significant absorption or scattering in the atmosphere. To quantify the
uncertainty associated with such an approach, we collate the various
contributions to the uncertainty, and we verify the consistency of
radiation-energy calculations from microscopic simulation codes by comparing
Monte Carlo simulations made with the two codes CoREAS and ZHAireS. We compare
a large set of simulations with different primary energies and shower
directions and observe differences in the radiation energy prediction for the
30 - 80 MHz band of 5.2 %. This corresponds to an uncertainty of 2.6 % for the
determination of the absolute cosmic-ray energy scale. Our result has general
validity and can be built upon directly by experimental efforts for the
calibration of the cosmic-ray energy scale on the basis of radio emission
measurements.Comment: 22 pages, 3 figures, accepted for publication in Astroparticle
Physic
CoREAS simulations of inclined air showers predict refractive displacement of the radio-emission footprint
Refractive displacement of the radio-emission footprint of inclined air showers simulated with CoREAS
The footprint of radio emission from extensive air showers is known to exhibit asymmetries due to the superposition of geomagnetic and charge-excess radiation. For inclined air showers a geometric early-late effect disturbs the signal distribution further. Correcting CoREAS simulations for these asymmetries reveals an additional disturbance in the signal distribution of highly inclined showers in atmospheres with a realistic refractive index profile. This additional apparent asymmetry in fact arises from a systematic displacement of the radio-emission footprint with respect to the Monte-Carlo shower impact point on the ground. We find a displacement of âŒ1500 m in the ground plane for showers with a zenith angle of 85°, illustrating that the effect is relevant in practical applications. A model describing this displacement by refraction in the atmosphere based on Snellâs law yields good agreement with our observations from CoREAS simulations. We thus conclude that the displacement is caused by refraction in the atmosphere
High energy astroparticle physics for high school students
The questions about the origin and type of cosmic particles are not only
fascinating for scientists in astrophysics, but also for young enthusiastic
high school students. To familiarize them with research in astroparticle
physics, the Pierre Auger Collaboration agreed to make 1% of its data publicly
available. The Pierre Auger Observatory investigates cosmic rays at the highest
energies and consists of more than 1600 water Cherenkov detectors, located near
Malarg\"{u}e, Argentina. With publicly available data from the experiment,
students can perform their own hands-on analysis. In the framework of a
so-called Astroparticle Masterclass organized alongside the context of the
German outreach network Netzwerk Teilchenwelt, students get a valuable insight
into cosmic ray physics and scientific research concepts. We present the
project and experiences with students.Comment: 8 pages, 5 figures, Proceedings of the 34th International Cosmic Ray
Conference (ICRC2015), The Hague, The Netherlands, PoS(ICRC2015)30
Systematic uncertainty of first-principle calculations of the radiation energy emitted by extensive air showers
The energy of extensive air showers can be determined from the energy radiated in the form of radio signals. The so-called radiation energy can be predicted with modern simulation codes using first-principle calculations without the need of free parameters. Here, we verify the consistency of radiation energy calculations by comparing a large set of Monte Carlo simulations made with the two codes CoREAS and ZHAireS. For the frequency band of 30 â 80 MHz, typically used by many current radio detectors, we observe a difference in the radiation energy prediction of 5.2%. This corresponds to a radio emission modelling uncertainty of 2.6% for thedetermination of the absolute cosmic-ray energy scale. Hence, radio detection offers the opportunity for a precise, accurate and independent measurement of the absolute energy of cosmic rays
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
- âŠ