Energy dependence of air fluorescence yield measured by AIRFLY Ave, M.; Bohacova, M.; Buonomo, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2008, Letnik:
597, Številka:
1
Journal Article
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Odprti dostop
In the fluorescence detection of ultra high energy (
≳
10
18
eV
) cosmic rays, the number of emitted fluorescence photons is assumed to be proportional to the energy deposited in air by shower ...particles. We have performed measurements of the fluorescence yield in atmospheric gases excited by electrons over energies ranging from keV to hundreds of MeV in several accelerators. We found that within the measured energy ranges the proportionality holds at the level of few %.
A novel method for the absolute fluorescence yield measurement by AIRFLY Ave, M.; Bohacova, M.; Buonomo, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2008, Letnik:
597, Številka:
1
Journal Article
Recenzirano
Odprti dostop
One of the goals of the AIRFLY (AIR FLuorescence Yield) experiment is to measure the absolute fluorescence yield induced by electrons in air to better than 10% precision. We introduce a new technique ...for measurement of the absolute fluorescence yield of the 337
nm line that has the advantage of reducing the systematic uncertainty due to the detector calibration. The principle is to compare the measured fluorescence yield to a well known process—the Cherenkov emission. Preliminary measurements taken in the BFT (Beam Test Facility) in Frascati, Italy with 350
MeV electrons are presented. Beam tests in the Argonne Wakefield Accelerator at the Argonne National Laboratory, USA with 14
MeV electrons have also shown that this technique can be applied at lower energies.
ABSTRACT
A thorough search for large-scale anisotropies in the distribution of arrival
directions of cosmic rays detected above 10
18
eV at the Pierre Auger
Observatory is presented. This search is ...performed as a function of both
declination and right ascension in several energy ranges above 10
18
eV, and reported in terms of dipolar and quadrupolar coefficients. Within the
systematic uncertainties, no significant deviation from isotropy is revealed.
Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole
moments in this energy range, upper limits on their amplitudes are derived.
These upper limits allow us to test the origin of cosmic rays above
10
18
eV from stationary Galactic sources densely distributed in
the Galactic disk and predominantly emitting light particles in all
directions.
The Pierre Auger Observatory, in Argentina, is the present flagship experiment studying ultrahigh-energy cosmic rays (UHECRs). Facing the challenge due to low cosmic-ray flux at the highest energies, ...the Observatory has been taking data for more than a decade, reaching an exposure of over 50 000 km2 sr yr. The combination of a large surface detector array and fluorescence telescopes provides a substantial improvement in energy calibration and extensive air shower measurements, resulting in data of unprecedented quality. Moreover, the installation of a denser subarray has allowed extending the sensitivity to lower energies. Altogether, this contributes to provide important information on key questions in the UHECR field in the energy range from 0.1 EeV up to 100 EeV. A review of main results from the Pierre Auger Observatory is presented with a particular focus on the energy spectrum measurements, the mass composition studies, the arrival directions analyses, the search for neutral cosmic messengers, and the investigation of high-energy hadronic interactions. Despite this large amount of valuable results, the understanding of the nature of UHECRs and of their origin remains an open science case that the Auger collaboration is planning to address with the AugerPrime project to upgrade the Observatory.
It is planned to operate the Pierre Auger Observatory until at least the end of 2024. An upgrade of the experiment has been proposed in order to provide additional measurements to allow one to ...elucidate the mass composition and the origin of the flux suppression at the highest energies, to search for a flux contribution of protons up to the highest energies and to reach a sensitivity to a contribution as small as 10% in the flux suppression region, to study extensive air showers and hadronic multi-particle production. With operation planned until 2024, event statistics will more than double compared with the existing Auger data set, with the critical added advantage that every event will now have mass information. Obtaining additional composition-sensitive information will not only help to better reconstruct the properties of the primary particles at the highest energies, but also improve the measurements in the energy range just above the ankle. Furthermore, measurements with the new detectors will help to reduce systematic uncertainties related to the modelling hadronic showers and to limitations in the reconstruction algorithms. A description of the principal proposed Auger upgrade will be presented. The Auger upgrade promises high-quality future data, and real scope for new physics.
We present the lastest results and status of the Auger Engineering Radio Array (AERA), located within the Pierre Auger Observatory. AERA, with more than 150 radio stations spread over 17 km2, is the ...largest radio detector in the world for extensive air showers above 1017 eV. The electric field emitted by secondary electrons and positrons allows us to estimate all characteristics of the primary cosmic ray: arrival direction, energy and mass composition. The performance of AERA together with the analysis methods are described. The final aim of AERA is mainly to improve the composition estimation of ultra-high energy cosmic rays as a standalone detector or in association with other instruments such as a ground particle detector or a fluorescence telescope.
We present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed ...for energies above 5 EeV, i.e. the region of the all-particle spectrum above the so-called “ankle”’ feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated with a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies and hard spectral indices. The impact of various systematic uncertainties on the above result is discussed.
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10^18 eV at the Pierre Auger Observatory is reported. For the first time, these ...large-scale anisotropy searches are performed as a function of both the right ascension and the declination and expressed in terms of dipole and quadrupole moments. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Upper limits on dipole and quadrupole amplitudes are derived under the hypothesis that any cosmic ray anisotropy is dominated by such moments in this energy range. These upper limits provide constraints on the production of cosmic rays above 1018 eV, since they allow us to challenge an origin from stationary galactic sources densely distributed in the galactic disk and emitting predominantly light particles in all directions.
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory is reported. For the first time, these ...large-scale anisotropy searches are performed as a function of both the right ascension and the declination and expressed in terms of dipole and quadrupole moments. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Upper limits on dipole and quadrupole amplitudes are derived under the hypothesis that any cosmic ray anisotropy is dominated by such moments in this energy range. Finally, these upper limits provide constraints on the production of cosmic rays above 1018 eV, since they allow us to challenge an origin from stationary galactic sources densely distributed in the galactic disk and emitting predominantly light particles in all directions.
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