scholarly journals ULTRA–HIGH-ENERGY COSMIC RAYS

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1950-1961 ◽  
Author(s):  
STEFAN WESTERHOFF
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
Energy Loss ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
New Era ◽  
High Energy Cosmic Rays ◽  
Open Questions ◽  
The Many

One of the most striking astrophysical phenomena today is the existence of cosmic ray particles with energies in excess of 1020 eV. While their presence has been confirmed by a number of experiments, it is not clear where and how these particles are accelerated to these energies and how they travel astronomical distances without substantial energy loss. We are entering an exciting new era in cosmic ray physics, with instruments now producing data of unprecedented quality and quantity to tackle the many open questions. This paper reviews the current experimental status of cosmic ray physics and summarizes recent results on the energy spectrum and arrival directions of ultra-high-energy cosmic rays.

scholarly journals CHASING THE GZK WITH HiRes

2003 ◽  
Vol 18 (18) ◽  
pp. 1235-1245 ◽  
Author(s):  
DOUGLAS R. BERGMAN
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
Energy Loss ◽  
High Energy ◽  
Cosmological Evolution ◽  
Similar Distribution ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
Luminous Matter ◽  
The Universe

The HiRes collaboration has recently announced preliminary measurements of the energy spectrum of ultra-high energy cosmic rays (UHECR), as seen in monocular analyses from each of the two HiRes sites. This spectrum is consistent with the existence of the GZK cutoff, as well other aspects of the energy loss processes that cause the GZK cutoff. Based on the analytic energy loss formalism of Berezinsky et al., the HiRes spectra favor a distribution of extragalactic sources that has a similar distribution to that of luminous matter in the universe, both in its local over-density and in its cosmological evolution.

Significance of the second dip in the ultra-high energy cosmic ray spectrum

Open Physics ◽  
2007 ◽  
Vol 5 (4) ◽  
Author(s):  
Tadeusz Wibig
Keyword(s):  
Cosmic Rays ◽  
Energy Loss ◽  
Cosmic Ray ◽  
High Energy ◽  
Energy Calibration ◽  
Ultra High Energy ◽  
Calibration Point ◽  
High Energy Cosmic Rays ◽  
Continuous Energy ◽  
New Feature

AbstractA new feature in the spectrum of ultra high energy cosmic rays (UHECR) has been announced in the paper by Berezinsky, Gazizov and Kachelrieβ. The ratio of the solution of the exact transport equation to its solution in the continuous energy loss limit shows intriguing features which, according to the Authors, are related to the very nature of the energy loss processes of UHECR: the very sharp second dip predicted at 6.3 × 1019 eV can be used as an energy calibration point and also as the UHECR mass indicator for big future cosmic ray experiments. In the present paper we would like to advocate that this statement is an overinterpretation. The second dip is a result of an inappropriate approximation used, and thus it cannot help to understand the nature of UHECR in any way.

scholarly journals High energy cosmic ray interactions and UHECR composition problem

2019 ◽  
Vol 210 ◽  
pp. 02001
Author(s):  
Sergey Ostapchenko
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Hadronic Interactions ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Interactions ◽  
Composition Problem

The differences between contemporary Monte Carlo generators of high energy hadronic interactions are discussed and their impact on the interpretation of experimental data on ultra-high energy cosmic rays (UHECRs) is studied. Key directions for further model improvements are outlined. The prospect for a coherent interpretation of the data in terms of the UHECR composition is investigated.

ULTRA HIGH ENERGY COSMIC RAYS WITH THE PIERRE AUGER OBSERVATORY

2012 ◽  
Vol 18 ◽  
pp. 221-229
Author(s):  
◽  
J. R. T. DE MELLO NETO
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
Cross Section ◽  
High Energy ◽  
Pierre Auger Observatory ◽  
Mass Composition ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
The Status ◽  
Shower Maximum

We present the status and the recent measurements from the Pierre Auger Observatory. The energy spectrum is described and its features discussed. We report searches for anisotropy of cosmic rays arrival directions in large scales and through correlation with catalogues of celestial objects. The measurement of the cross section proton-air is discussed. Finally, the mass composition is addressed with the measurements of the variation of the depth of shower maximum with energy and with the muon density at ground.

scholarly journals The Pierre Auger Observatory: Review of Latest Results and Perspectives

Universe ◽  
2018 ◽  
Vol 4 (11) ◽  
pp. 128 ◽  
Author(s):  
Dariusz Góra ◽  
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
Detection System ◽  
Cosmic Ray ◽  
High Energy ◽  
Pierre Auger Observatory ◽  
Mass Composition ◽  
Ultra High Energy ◽  
Energy Limitation ◽  
Arrival Directions

The Pierre Auger Observatory is the world’s largest operating detection system for the observation of ultra high energy cosmic rays (UHECRs), with energies above 10 17 eV. The detector allows detailed measurements of the energy spectrum, mass composition and arrival directions of primary cosmic rays in the energy range above 10 17 eV. The data collected at the Auger Observatory over the last decade show the suppression of the cosmic ray flux at energies above 4 × 10 19 eV. However, it is still unclear if this suppression is caused by the energy limitation of their sources or by the Greisen–Zatsepin–Kuzmin (GZK) cut-off. In such a case, UHECRs would interact with the microwave background (CMB), so that particles traveling long intergalactic distances could not have energies greater than 5 × 10 19 eV. The other puzzle is the origin of UHECRs. Some clues can be drawn from studying the distribution of their arrival directions. The recently observed dipole anisotropy has an orientation that indicates an extragalactic origin of UHECRs. The Auger surface detector array is also sensitive to showers due to ultra high energy neutrinos of all flavors and photons, and recent neutrino and photon limits provided by the Auger Observatory can constrain models of the cosmogenic neutrino production and exotic scenarios of the UHECRs origin, such as the decays of super heavy, non-standard-model particles. In this paper, the recent results on measurements of the energy spectrum, mass composition and arrival directions of cosmic rays, as well as future prospects are presented.

scholarly journals COLOR GLASS CONDENSATE IN BRANE MODELS OR DON'T ULTRA HIGH ENERGY COSMIC RAYS PROBE 1015eV SCALE?

2005 ◽  
Vol 20 (06) ◽  
pp. 419-440 ◽  
Author(s):  
HOURI ZIAEEPOUR
Keyword(s):  
Cosmic Rays ◽  
Extra Dimension ◽  
Cosmic Ray ◽  
High Energy ◽  
Effective Density ◽  
Color Glass ◽  
Color Glass Condensate ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
Brane Models

In a previous work1 we have studied the propagation of relativistic particles in the bulk for some of the most popular brane models. Constraints have been put on the parameter space of these models by calculating the time delay due to propagation in the bulk of particles created during the interaction of Ultra High Energy Cosmic Rays (UHECRs) with protons in the terrestrial atmosphere. The question was, however, raised that probability of hard processes in which bulk modes can be produced is small and consequently, the tiny flux of UHECRs cannot constrain brane models. Here we use Color Glass Condensate (CGC) model to show that effects of extra dimensions are visible not only in hard processes when the incoming photon/parton hits a massive Kaluza–Klein mode but also through the modification of soft/semi-hard parton distribution. At classical level, for an observer in the CM frame of UHECR and atmospheric hadrons, color charge sources are contracted to a thin sheet with a width inversely proportional to the energy of the ultra energetic cosmic ray hadron and consequently they can see an extra dimension with comparable size. Due to QCD interaction, a short life swarm of partons is produced in front of the sheet and its partons can penetrate to the extra-dimension bulk. This reduces the effective density of partons on the brane or in a classical view creates a delay in the arrival of the most energetic particles if they are reflected back due to the warping of the bulk. In CGC approximation the density of swarm at different distances from the classical sheet can be related and therefore it is possible (at least formally) to determine the relative fraction of partons in the bulk and on the brane at different scales. Results of this work are also relevant to the test of brane models in hadron colliders like LHC.

scholarly journals CODALEMA: A COSMIC RAY AIR SHOWER RADIO DETECTION EXPERIMENT

2006 ◽  
Vol 21 (supp01) ◽  
pp. 192-196 ◽  
Author(s):  
D. ARDOUIN ◽  
A. BELLETOILE ◽  
D. CHARRIER ◽  
R. DALLIER ◽  
L. DENIS ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Air Showers ◽  
Detection Experiment ◽  
Transient Signals ◽  
High Energy Cosmic Rays ◽  
Air Shower ◽  
Radio Detection

The CODALEMA experimental device currently detects and characterizes the radio contribution of cosmic ray air showers : arrival directions and electric field topologies of radio transient signals associated to cosmic rays are extracted from the antenna signals. The measured rate, about 1 event per day, corresponds to an energy threshold around 5.1016eV. These results allow to determine the perspectives offered by the present experimental design for radiodetection of Ultra High Energy Cosmic Rays at a larger scale.

scholarly journals Energy spectrum of ultra-high energy cosmic rays observed with the Telescope Array using a hybrid technique

2015 ◽  
Vol 61 ◽  
pp. 93-101 ◽  
Author(s):  
T. Abu-Zayyad ◽  
R. Aida ◽  
M. Allen ◽  
R. Anderson ◽  
R. Azuma ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
High Energy ◽  
Hybrid Technique ◽  
Ultra High Energy ◽  
Telescope Array ◽  
High Energy Cosmic Rays
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