Download or read book An Upper Limit to the Photon Fraction in Cosmic Rays Above 10 19 eV from the Pierre Auger Observatory written by and published by . This book was released on 2006 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: An upper limit of 16% (at 95% c.l.) is derived for the photon fraction in cosmic rays with energies above 1019 eV, based on observations of the depth of shower maximum performed with the hybrid detector of the Pierre Auger Observatory. This is the first such limit on photons obtained by observing the fluorescence light profile of air showers. This upper limit confirms and improves on previous results from the Haverah Park and AGASA surface arrays. Additional data recorded with the Auger surface detectors for a subset of the event sample, support the conclusion that a photon origin of the observed events is not favored.
Download or read book Upper limit on the primary photon fraction from Pierre Auger Observatory written by Markus Risse and published by . This book was released on 2005 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on observations of the depth of shower maximum performed with the hybrid detector of the Auger Observatory, an upper limit on the cosmic-ray photon fraction of 26% (at 95% confidence level) is derived for primary energies above 10{sup 19} eV. Additional observables recorded with the surface detector array, available for a sub-set of the data sample, support the conclusion that a photon origin of the observed events is not favoured.
Download or read book Development of a Sub glacial Radio Telescope for the Detection of GZK Neutrinos written by Thomas Meures and published by Springer. This book was released on 2015-05-29 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of the project presented in this book is to detect neutrinos created by resonant interactions of ultrahigh energy cosmic rays on the CMB photon field filling the Universe. In this pioneering first analysis, the author puts forward much of the analysis framework, including calibrations of the electronic hardware and antenna geometry, as well as the development of algorithms for event reconstruction and data reduction. While only two of the 37 stations planned for the Askaryan Radio Array were used in this assessment of 10 months of data, the analysis was able to exclude neutrino fluxes above 10 PeV with a limit not far from the best current limit set by the IceCube detector, a result which establishes the radio detection technique as the path forward to achieving the massive volumes needed to detect these ultrahigh energy neutrinos.
Download or read book Measurement of the Energy Spectrum of Cosmic Rays Above 3 X 1017 EV Using the Infill Array of the Pierre Auger Observatory written by Rivera Bretel Hugo Marcelo and published by . This book was released on 2013 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pierre Auger Observatory, in Argentina, combines a 3000 $\mathrm{km^2}$ surface array of water Cherenkov detectors with fluorescence telescopes to measure extensive air showers initiated by ultra-high energy cosmic rays. This "hybrid" observatory (in operation since 2004, and completed in 2008) is fully efficient for cosmic rays energies above $10^{18}$ eV, that is, from just below the "ankle" of the energy spectrum up to the highest energies.After the completion of the main observatory, the Auger collaboration has started to deploy new instruments to extend the energy range down to about 0.1 EeV. The planned extensions include two infill surface arrays with 750 and 433 m spacing, with muon detection capabilities, and three additional fluorescence telescopes with a more elevated field of view. The 750 m infill array (covering about 24 $\mathrm{km^2}$) and the new telescopes are now operational. Their aim is the measurement of cosmic rays from below the second knee of the spectrum up to the ankle, where data from the extensions overlap those from the main observatory. The study of the evolutior of the spectrum through the second knee and the ankle, together with the primary mass composition, are crucial to the understanding of the transition from a galactic cosmic ray origin to an extragalactic one.This thesis makes use of data from the 750 m infill array: the objective is the measurement of the cosmic ray energy spectrum in the energy region above $3 \times 10^{17}$ eV, where the array is fully efficient. To get to the energy spectrum, several steps are needed, from the reconstruction of events, through the precise determination of the exposure of the array, up to the determination of the primary energy. The thesis deals with these aspects, before reaching the final result.The first chapter gives a general introduction to cosmic ray physics and detectors. It also summarizes experimental results above the first knee of the spectrum with particular emphasis on those obtained above $10^{17}$ eV. The next two chapters describe the Pierre Auger Observatory and the infill array, respectively. In chapter 2, the main Auger results are summarized too, after a schematic description of th different components of the observatory. Chapter 3 sets the stage for the following chapters. It presents a more detailed description of the characteristics of the infill array, in particular the trigger definitions, event selection and reconstruction. In chapter 4 the performance of the reconstruction of the lateral distribution of observed showers is studied in detail. This is particularly important for the energy spectrum, since the signal at a fixed distance from the shower axis is used as the energy estimator of the event. This signal is estimated by means c the measured lateral distribution of the shower. Chapter 5 presents a comparison between the event reconstruction of the infill and main arrays. Using the set of showers detected by both instruments, the derived geometry and energy estimation are compared, showing a good agreement. In chapter 6, the energy threshold of the array, and hence the set of events to be used, is defined. The methods to obtain the exposure of the array are discussed, as well as related systematic uncertainties. Finally, in chapter 7, the technique to derive the primary energy for each detected shower is presented. The derived energy spectrum is discussed, and the flux is shown to be consistent with that measured by other instruments in the overlapping energy regions.
Download or read book Features of the Energy Spectrum of Cosmic Rays Above 2 5 times 10 18 EV Using the Pierre Auger Observatory written by Alexander Aab and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultra high Energy Particle Astrophysics written by Shigeru Yoshida and published by Nova Publishers. This book was released on 2003 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many kinds of radiation exist in the universe, including photons and particles with a wide range of energies. Some of the radiation is produced in stars and galaxies, and some is cosmological background radiation, a relic from the history of cosmic evolution. Among all this radiation, the most energetic are cosmic ray particles: nucleons, nuclei, and even extremely energetic gamma rays. There are some observational facts about cosmic rays to give suggestions on their origin. The most important one among them is that the energy spectrum of high energy cosmic rays above 10 GeV (where the magnetic field of the sun is no longer a concern) is well represented by a power law form. This indicates cosmic ray particles are products of non-thermal processes. Their energy extends over more than 13 decades from 107 eV up to 1020 eV. In terms of its structure, the spectrum can be divided into three regions: two 'knees' and one 'ankle'. The first 'knee' appears around 3×1015 eV where the spectral power law index changes from -2.7 to -3.0. The second 'knee' is somewhere between 1017 eV and 1018 eV where the spectral slope changes from -3.0 to around -3.3. The 'ankle' is seen at or after 3×1018 eV. Above that energy the spectral slope is around -2.7, but with a large uncertainty because of poor statistics and resolution. This book deals with the final and most energetic population, the Ultra High Energy Cosmic Rays (UHECRs).
Download or read book Large Scale Distribution of Arrival Directions of Cosmic Rays Detected Above 10 EV at the Pierre Auger Observatory written by and published by . This book was released on 2012 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Cosmic Ray Spectrum Above 4 1018 EV Using Inclined Events Detected with the Pierre Auger Observatory written by and published by . This book was released on 2015 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the cosmic-ray spectrum for energies exceeding 4×1018 eV is presented, which is based on the analysis of showers with zenith angles greater than 60° 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 5.3×1018 eV, the ``ankle'', the flux can be described by a power law E-[gamma] with index [gamma]=2.70 ± 0.02 (stat) ± 0.1 (sys) followed by a smooth suppression region. For the energy (Es) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25 (stat)+1.0-1.2 (sys))×1019 eV.
Download or read book Update on the Correlation of the Highest Energy Cosmic Rays with Nearby Extragalactic Matter written by and published by . This book was released on 2010 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuzmin energy threshold, 6 x 1019 eV. The anisotropy was measured by the fraction of arrival directions that are less than 3.1{sup o} from the position of an active galactic nucleus within 75 Mpc (using the Veron-Cetty and Veron 12th catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is (386{sup +7})%, compared with 21% expected for isotropic cosmic rays. This is down from the early estimate of (6913{sup +11})%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.
Download or read book The Cosmic Ray Spectrum at the Highest Energy written by Alessio Gorgi and published by . This book was released on 2009 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pierre Auger Observatory aims to study the ultra high energy cosmic rays with energies above 1 EeV. To get an accurate measurement of the characteristic of the extensive air showers that the cosmic rays generate in the atmosphere, the Observatory uses a hybrid technique. In this work we have studied the detector performance, including trigger and hardware efficiencies. We have optimized the event selection and estimated the efficiency of the detector acceptance. Uncertainties for event reconstruction were evaluated and propagated to the measured energy spectrum. We have shown that some stations that are not courrently considered part of the event can be included in the event selection procedure. We have studied the effect of loosing the signal of one of the three photomultipliers due to some failure, or the effect of the saturation of the ADC channels or of the photomultiplier to the reconstruction accuracy. The reconstruction uncertainty was also studied in case of ``normal'' events using a method based on fluctuations, to cross-check the results obtained using the fit accuracies. An evaluation of the trigger efficiency was also performed in case one of the three photomultipliers is missing. We have shown that the problems related to the instrumental apparatus only reduce the efficiency where it is not already 100\% and in most of the cases the reconstruction uncertainties are only slightly affected. Furthermore this work gives the first indication that the reconstruction uncertainties of the surface detector data do not change the index of the power law of the measured cosmic rays spectrum.
Download or read book Upper Limits on the Ultra high Energy Cosmic Ray Flux from Unresolved Sources written by Ross E. Burton and published by . This book was released on 2012 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pierre Auger Observatory is the world's largest ultra-high energy cosmic ray detector. Its goals include answering basic questions about the origins and composition of cosmic rays at the highest energies. We outline the scientific motivation for constructing such an observatory and we highlight some of the significant results produced so far by this world-class instrument. We present the results of our own contributions toward calibrating the timing characteristics of the instrument followed by two alternative techniques for analyzing cosmic ray arrival direction data. The first technique is based on a Bayesian statistical framework and is presented as a solution to some of the difficulties in applying a standard analysis to identify anisotropy in the cosmic ray flux. The second analysis we present is based on a Markov Chain Monte Carlo method for identifying sources of cosmic rays in our arrival direction data. We are able to use our method to set an upper limit of 0.15 per square km per year on the flux from any potential sources producing ultra-high energy cosmic rays with energy E{u2265}3 EeV. We conclude with a proposal for enhancing the already successful observatory with an array of non-imaging Cherenkov detectors. According to our simulation work, such an array could serve as both an independent measure of the cosmic ray energy and, if the array is dense enough, it could also provide insight into the composition of ultra-high energy cosmic rays on an event by event basis.
Download or read book Studies of the Highest Energy Cosmic Ray Air Showers with the Pierre Auger Observatory Hybrid Dectector written by Bei Cai and published by . This book was released on 2006 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Cosmic Ray Spectrum Above 4 u00D7 1018 EV Using Inclined Events Detected with the Pierre Auger Observatory written by and published by . This book was released on 2015 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the cosmic-ray spectrum for energies exceeding 4×1018 eV is presented, which is based on the analysis of showers with zenith angles greater than 60° 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 5.3×1018 eV, the à̀nkle'', the flux can be described by a power law E–? with index ?=2.70 ± 0.02 (stat) ± 0.1 (sys) followed by a smooth suppression region. For the energy (Es) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25 (stat)+1.0–1.2 (sys))×1019 eV.
Download or read book The ubiquitous mechanism accelerating cosmic rays at all the energies written by Antonio Codino and published by Società Editrice Esculapio. This book was released on 2021-02-04 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanism accelerating Cosmic rays in the milky way galaxy and galaxy clusters is identified and described. The acceleration of Cosmic rays is a purely electrostatic process which operate up to the maximum energies of 1023 ev in galaxy clusters. Galactic Cosmic rays are accelerated in a pervasive electrostatic field active in the whole galaxy except in restricted regions shielded by Interstellar and stellar plasma as, for instance, the region occupied by the Solar system. It is proved that the Energy spectrum of the Cosmic radiation in the milky way galaxy, in the region where the Solar system resides, has a constant Spectral index comprised between 2.64-2.68 and the maximum energies of galactic protons are 3.0 × 1019 ev. The agreement of these results with the experimental data is discussed in detail and highlighted. The various physical processes that maintain the stability of the electrostatic structure in the milky way galaxy are the same that generate the galactic magnetic field. Accordingly, the intensity, orientation and direction of the galactic magnetic field are evaluated. The results of the calculation are compared with the observation data, optical and mostly radio astronomi data. The accord of the intensity, orientation and direction of the observed magnetic field with calculation is excellent.
Download or read book Cosmic Rays Above 10 19 EV 1992 written by Murat Boratav and published by . This book was released on 1992 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Anisotropy and Chemical Composition of Ultra high Energy Cosmic Rays Using Arrival Directions Measured by the Pierre Auger Observatory written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E> E{sub th} = 5.5 x 1019 eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at E> E{sub th} are heavy nuclei with charge Z, the proton component of the sources should lead to excesses in the same regions at energies E/Z. We here report the lack of anisotropies in these directions at energies above E{sub th}/Z (for illustrative values of Z = 6,13,26). If the anisotropies above E{sub th} are due to nuclei with charge Z, and under reasonable assumptions about the acceleration process, these observations imply stringent constraints on the allowed proton fraction at the lower energies.
Download or read book Introduction To Ultrahigh Energy Cosmic Ray Physics written by Pierre Sokolsky and published by CRC Press. This book was released on 2018-03-08 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmic ray physics has recently attracted a great deal of attention from the high energy physics community because of the discovery of new sources and the advent of new techniques. The result of a series of lectures prepared for graduate students and postdoctoral researchers, this book is a general introduction to experimental techniques and results in the field of ultrahigh energy cosmic rays. It succinctly summarizes the rapidly developing field, and provides modern results that include data from newer detectors. Combining experiment and theory, the text explores the results of a single, easy-to-understand experiment to tie together various issues involved in the physics of ultrahigh energy cosmic rays.
