% IMPORTANT: The following is UTF-8 encoded. This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.
@PHDTHESIS{Glaser:686745,
author = {Glaser, Jens Christian},
othercontributors = {Erdmann, Martin and Wiebusch, Christopher},
title = {{A}bsolute energy calibration of the {P}ierre {A}uger
observatory using radio emission of extensive air showers},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
reportid = {RWTH-2017-02960},
pages = {1 Online-Ressource (v, 189 Seiten) : Illustrationen,
Diagramme},
year = {2017},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2017},
abstract = {Ultra-high-energy cosmic rays can be measured by short
radio pulses in the MHz regime emitted by extensive air
showers. This radio technique is complementary to existing
techniques such as surface detector arrays or fluorescence
telescopes. It has a duty cycle of almost $100\%$ and is
sensitive to all main air-shower observables such as the
cosmic-ray energy, mass, and arrival direction. In this
thesis, we developed a new method to determine the
cosmic-ray energy. We showed that the radio technique is
especially useful to determine the cosmic-ray energy with
high accuracy and is superior to existing techniques in term
of achievable accuracy. This is because the radio emission
from air showers can be calculated from first principles,
and radio waves are less influenced by environmental
conditions compared to, e.g., fluorescence light. As an
accurate energy scale is crucial for the interpretation of
cosmic-ray measurements, the radio technique will thus be
able to significantly advance this field of research. We
first studied the energy released in air showers in the form
of MHz radiation in detail, using CoREAS air-shower
simulations. Depending on the distance between the observer
and the region in the atmosphere where the radiation is
released, the shape of the signal distribution on the ground
changes significantly. For small distances to the emission
region, the signal distribution is narrow around the shower
axis with large energies per unit area, whereas for large
distances to the emission region the radiation energy is
distributed over a larger area resulting in a broad signal
distribution with a small amount of energy per unit area. As
soon as the air shower has emitted all its radiation energy,
the total radiation energy, i.e., the integral over the
signal distribution on the ground, remains constant. In
particular, it does not depend on the spacial signal
distribution on the ground or on the observation altitude
and is thus directly comparable between different
experiments.The simulated radiation energy – corrected for
the dependence on the geomagnetic field – correlates best
with the energy contained in the electromagnetic part of the
air shower and exhibits quadratic scaling with the
electromagnetic shower energy, as is expected for coherent
emission. The electromagnetic shower energy can be converted
to the primary cosmic-ray energy using predictions from
hadronic interaction models or a direct measurement of the
invisible energy fraction alternatively.The simulated
radiation energy has a second-order dependency on the air
density of the emission region. After correcting this
effect, the corrected radiation energy and the
electromagnetic shower energy have a scatter of less than
$3\%.$ In addition, we presented a more practical
parametrization of the dependence between radiation energy
and electromagnetic shower energy using only the geometry of
the air shower, i.e., without using Xmax information, and
obtained a resolution of $4\%.$ This scatter of $4\%$ is
well below current experimental uncertainties, so that the
radiation energy is well suited to estimate the cosmic-ray
energy.If the radiation energy is detected at a particular
observation height, the air shower may not have released all
its radiation energy. The strength of this clipping effect
depends on the atmospheric depth between observation height
and shower maximum. We presented a parametrization of this
effect that can be used in experiments to correctly
determine the full radiation energy and thereby estimate the
cosmic-ray energy. The radiation energy is influenced less
by clipping than the electromagnetic part of the air shower
as the radiation energy is released earlier in the shower
development.Then, we used data from the Auger Engineering
Radio Array (AERA) which is the radio detector of the Pierre
Auger Observatory. AERA is located within the low-energy
extension of the Observatory where additional surface
detector stations with a smaller spacing are present, which
enables access to cosmic-ray energies down to 0.1 EeV. To
most accurately determine the cosmic-ray energy, we only use
the thoroughly calibrated 24 LPDA radio stations of the
first stage of AERA deployment, with data collected between
April 2011 and March 2013. At several observer positions,
the energy deposit per area of the radio pulse of an
extensive air shower is measured. Using recent progress in
understanding the lateral signal distribution of the radio
signals, this distribution is described by an empirical
function. The spatial integral of the lateral distribution
function gives the amount of energy that is transferred from
the primary cosmic ray into radio emission in the 30 to 80
MHz frequency band of AERA during the air-shower
development. We measured on average 15.8 MeV of radiation
energy for a 1 EeV air shower arriving perpendicularly to a
geomagnetic field of 0.24 G. The systematic uncertainty is
$28\%$ on the radiation energy and $16\%$ on the cosmic-ray
energy.Using the results from the simulation study, the
radiation energy is corrected for different emission
strengths at different angles between shower axis and
geomagnetic field, for changing emission strengths due to
different air densities in the emission region as well as
for missing radiation energy of air showers that are not
fully developed before reaching the ground. This corrected
radiation energy is compared with the calorimetric
air-shower energy obtained from the the surface-detector
reconstruction. Investigating the scatter around the
calibration curve and subtracting the resolution of the
surface detector we found that the energy resolution of the
radio detector is $20\%$ for the full data set, and $14\%$
for the events with more than four stations with signal,
where the core position could be determined in the radio LDF
fit. Given the small shower-to-shower fluctuations of the
electromagnetic component, we expect that with a deeper
understanding of the detector and environmental effects, an
even improved precision of the energy measurement can be
achieved.The first-principles calculations are compared to
the measurement of the radiation energy with respect to the
energy scale of the fluorescence detector (FD). We found
that the first-principles calculations predict $19\%$ larger
cosmic-ray energies than given by the FD energy scale at
energies around 1 EeV. The systematic uncertainty of the
radio energy scale is $15\%$ and is dominated by the
detector calibration that contributes with $14\%.$ Hence,
the radio technique is well competitive to the fluorescence
technique with its systematic uncertainty of $14\%$ at
energies above 1 EeV and $16\%$ at energies of around 0.3
EeV. In particular, the difference in the energy scales is
well compatible within the systematic uncertainties. In the
future, a significant improvement in the systematic
uncertainty of the radio energy scale is expected. Using the
results of a recently performed calibration campaign of the
antenna response, the total systematic uncertainty can be
reduced to $10\%.$ With further improvements in the antenna
calibration and more detailed first-principles calculations,
a reduction of the uncertainty to $7\%$ or below seems
realistic. Hence, the radio technique together with the
methods developed in this thesis can deliver unprecedented
accuracy of the cosmic-ray energy scale. This will allow for
a significant improvement in the interpretation of the
results of the Pierre Auger Observatory.},
cin = {133320 / 130000},
ddc = {530},
cid = {$I:(DE-82)133320_20140620$ / $I:(DE-82)130000_20140620$},
pnm = {GRK 1675 - GRK 1675: Teilchen- und Astroteilchenphysik im
Lichte von LHC (164315326)},
pid = {G:(GEPRIS)164315326},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2017-02960},
url = {https://publications.rwth-aachen.de/record/686745},
}
guest ::