Arrival Direction Probabilities of Ultra High Energy Cosmic Rays with the Pierre Auger Observatory and Progress Toward an In-situ Cross-calibration of Auger and Telescope Array Surface Detector Stations PDF Download
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Author: Sean P. Quinn Publisher: ISBN: Category : Astrophysics Languages : en Pages : 435
Book Description
The origin and nature of ultra-high energy cosmic rays is an open question in astrophysics since their discovery in the 1960s. Observed energies of these primary particles can approach greater than 10x the center of mass energies achieved at modern collider facilities, and there is presently no consensus for an astrophysical mechanism capable of reaching these energies. The Pierre Auger Observatory is the world's largest cosmic ray observatory, spanning ~3,000 km2, dedicated to this problem. After initial acceleration, the primary trajectory from source to solar system is not rectilinear due to magnetic deflection. This dissertation investigates how uncertainties of a modern galactic magnetic field model translate into arrival direction uncertainties for E>50 EeV events using a sensitivity analysis approach. In most cases it's found that uncertainties from B-field model dominate compared to observation systematic errors. Furthermore, the angular extent of 1s arrival direction contours is found to enclose many potential astrophysical objects, making it difficult to isolate individual sources. Implications for anisotropy studies are also briefly discussed.To enable full-sky coverage, Auger data can be combined with the Telescope Array Project, a similar array operating in the northern hemisphere. In both experiments most data are generated from the surface-detector (SD) array. The TA and Auger experiments use different SD station designs, giving them different sensitivities to extensive air-shower components. We seek to understand and cross-validate these complementary detectors on a hardware level using an in-situ approach to observe the same air showers. We describe the technical details associated with installing the detectors, data acquisition, and analysis of signals for this first stage of the Auger@TA project. Integrated signals are compared to a collection of models, and in general are found to agree with expectations. For a subsample of events air-shower parameters are available, and a sophisticated simulation is run to predict the expected response of the two detectors, which is compared to observed data. These simulations appear to show some discrepancy. Characterizing and understanding the discrepancies will be important for taking full advantage of future planned upgrades to both experiments, especially in the context of atomic composition measurements.
Author: Sean P. Quinn Publisher: ISBN: Category : Astrophysics Languages : en Pages : 435
Book Description
The origin and nature of ultra-high energy cosmic rays is an open question in astrophysics since their discovery in the 1960s. Observed energies of these primary particles can approach greater than 10x the center of mass energies achieved at modern collider facilities, and there is presently no consensus for an astrophysical mechanism capable of reaching these energies. The Pierre Auger Observatory is the world's largest cosmic ray observatory, spanning ~3,000 km2, dedicated to this problem. After initial acceleration, the primary trajectory from source to solar system is not rectilinear due to magnetic deflection. This dissertation investigates how uncertainties of a modern galactic magnetic field model translate into arrival direction uncertainties for E>50 EeV events using a sensitivity analysis approach. In most cases it's found that uncertainties from B-field model dominate compared to observation systematic errors. Furthermore, the angular extent of 1s arrival direction contours is found to enclose many potential astrophysical objects, making it difficult to isolate individual sources. Implications for anisotropy studies are also briefly discussed.To enable full-sky coverage, Auger data can be combined with the Telescope Array Project, a similar array operating in the northern hemisphere. In both experiments most data are generated from the surface-detector (SD) array. The TA and Auger experiments use different SD station designs, giving them different sensitivities to extensive air-shower components. We seek to understand and cross-validate these complementary detectors on a hardware level using an in-situ approach to observe the same air showers. We describe the technical details associated with installing the detectors, data acquisition, and analysis of signals for this first stage of the Auger@TA project. Integrated signals are compared to a collection of models, and in general are found to agree with expectations. For a subsample of events air-shower parameters are available, and a sophisticated simulation is run to predict the expected response of the two detectors, which is compared to observed data. These simulations appear to show some discrepancy. Characterizing and understanding the discrepancies will be important for taking full advantage of future planned upgrades to both experiments, especially in the context of atomic composition measurements.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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 80MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy density 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. We found that 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 15.8MeV 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. Finally 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.
Author: Philip Wahrlich Publisher: ISBN: Category : Cosmic rays Languages : en Pages : 480
Book Description
"The Pierre Auger Observatory (PAO) was constructed to study the highest energy cosmic rays (UHECR). A hybrid of ground array and fluorescence detector, it is the largest ultra-high energy cosmic ray detector to date. As such, the PAO detects UHECR in unprecedented amounts, offering unique insights into the nature and origin of these most extraordinarily energetic particles in the universe. In this thesis we improve the accuracy of arrival direction uncertainty estimates for reconstructed events. We validate these improved uncertainty estimators through a number of statistical techniques, involving both recorded and simulated data. Furthermore, we identify and correct a number of systematic errors which arise in algorithmic corner cases. We propose novel techniques for measuring the time synchronisation of each detector in the using recorded air shower data. We use these techniques to measure the synchronisation of each detector across the PAO surface detector and fluorescence detector. Finally, we perform a cursory search for a point source of UHECR at the Galactic centre. A slight over-density of events is measured from the direction of the Galactic centre, however this over-density is not substantial enough to indicate a departure from isotropy." -- page 12.
Author: Andrea Biscoveanu Publisher: ISBN: Category : Languages : en Pages :
Book Description
The mass composition of cosmic rays is an important parameter for determining their origin. Using both fluorescence and surface detectors, The Pierre Auger Observatory measures the depth of shower maximum, Xmax, from which the mass of the primary particle can be inferred. The surface detector measurement, which is based on the principle of shower universality, increases the number of available statistics for Xmax by at least a factor of 10 since it is no longer limited by the low duty cycle of the fluorescence detector. We compare the energy and arrival directions determined using this new reconstruction to both the official surface and fluorescence detector reconstructions and present an event by event comparison of the \Xmax values calculated using both types of detectors for events with energies above 10^{18.8} eV. We use this new reconstruction method based on universality to conduct preliminary anisotropy studies discriminating by the mass of the primary particle.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The data collected by the Pierre Auger Observatory are analyzed to search for coincidences between the arrival directions of high-energy cosmic rays and the positions in the sky of astrophysical transients. Special attention is directed towards gamma ray observations recorded by NASA's Swift mission, which have an angular resolution similar to that of the Auger surface detectors. In particular, we check our data for evidence of a signal associated with the giant flare that came from the soft gamma repeater 1806-20 on December 27, 2004.
Author: Laura Collica Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The Pierre Auger Observatory studies Ultra High Energy Cosmic Rays (UHECRs) physics. The flux of UHECRs is very low (less than 1 particle/km2-year) and their properties must be inferred from the measurements of the secondary particles that the cosmic ray primary produces in the atmosphere. These particles cascades are called Extensive Air Showers (EAS) and can be studied at ground by deploying detectors covering large areas. The EAS physics is complex, and the properties of secondary particles depend strongly on the first interaction, which takes place at an energy beyond the ones reached at accelerators. As a consequence, the analysis of UHECRs is subject to large uncertainties and hence many of their properties, in particular their composition, are still unclear. Two complementary techniques are used at Auger to detect EAS initiated by UHECRs: a 3000 km2 surface detector (SD) array of water Cherenkov tanks which samples particles at ground level and fluorescence detectors (FD) which collect the ultraviolet light emitted by the de-excitation of nitrogen nuclei in the atmosphere, and can operate only in clear, moonless nights. The main goal of this thesis is the measurement of UHECR mass composition using data from the SD of the Pierre Auger Observatory. Measuring the cosmic ray composition at the highe-st energies is of fundamental importance for particle physics and astrophysics. Indeed, it allows to explore the hadronic interactions at ultra-high energies, and to discriminate between different scenarios of origin and propagation of cosmic rays.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Correlation of the highest energy cosmic rays with nearby extragalactic objects in Pierre Auger Observatory data; (2) Discriminating potential astrophysical sources of the highest energy cosmic rays with the Pierre Auger Observatory; (3) Intrinsic anisotropy of the UHECR from the Pierre Auger Observatory; (4) Ultra-high energy photon studies with the Pierre Auger Observatory; (5) Limits on the flux of diffuse ultra high energy neutrinos set using the Pierre Auger Observatory; (6) Search for sidereal modulation of the arrival directions of events recorded at the Pierre Auger Observatory; (7) Cosmic Ray Solar Modulation Studies in the Pierre Auger Observatory; (8) Investigation of the Displacement Angle of the Highest Energy Cosmic Rays Caused by the Galactic Magnetic Field; (9) Search for coincidences with astrophysical transients in Pierre Auger Observatory data; and (10) An alternative method for determining the energy of hybrid events at the Pierre Auger Observatory.
Author: J. Matthews Publisher: ISBN: Category : Languages : en Pages : 4
Book Description
A discussion is given of the highest energy events so far recorded by the Pierre Auger Observatory. We present these to illustrate the quality of the information that they contain. The surface detectors are used to measure a rich set of parameters that will eventually help characterize the mass of the incoming primary particle.
Author: Publisher: ISBN: Category : Languages : en Pages : 15
Book Description
Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with $E \ge 6 \times 10^$ eV by analyzing cosmic rays with energies above $E \ge 5 \times 10^$ eV arriving within an angular separation of approximately 15$^{\circ }$ . We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.
Author: Sean P. Quinn
Author: Sean P. Quinn
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Author: Philip Wahrlich
Author: Andrea Biscoveanu
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Author: Marius Grigat
Author: Laura Collica
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Author: J. Matthews
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