ORCID Profile
0000-0002-9040-9648
Current Organisations
Mount Sinai West and Morningside
,
University of Adelaide
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Astronomical and Space Sciences | Cosmic Ray Physics | High Energy Astrophysics; Cosmic Rays | Astronomy And Astrophysics | Atmospheric Sciences Not Elsewhere Classified
Expanding Knowledge in the Physical Sciences | Physical sciences | International relations not elsewhere classified | Higher education |
Publisher: IOP Publishing
Date: 21-09-2020
Publisher: Elsevier BV
Date: 11-2004
Publisher: Springer Science and Business Media LLC
Date: 05-1969
DOI: 10.1038/222635A0
Publisher: American Geophysical Union (AGU)
Date: 11-02-2005
DOI: 10.1029/2004JD005390
Publisher: Elsevier BV
Date: 10-1994
Publisher: arXiv
Date: 2017
Publisher: American Physical Society (APS)
Date: 27-10-1980
Publisher: Elsevier BV
Date: 10-2016
Publisher: American Geophysical Union (AGU)
Date: 04-2020
DOI: 10.1029/2019EA000582
Abstract: Elves are a class of transient luminous events, with a radial extent typically greater than 250 km, that occur in the lower ionosphere above strong electrical storms. We report the observation of 1,598 elves, from 2014 to 2016, recorded with unprecedented time resolution (100 ns) using the fluorescence detector (FD) of the Pierre Auger Cosmic‐Ray Observatory. The Auger Observatory is located in the Mendoza province of Argentina with a viewing footprint for elve observations of km , reaching areas above the Pacific and Atlantic Oceans, as well as the Córdoba region, which is known for severe convective thunderstorms. Primarily designed for ultrahigh energy cosmic‐ray observations, the Auger FD turns out to be very sensitive to the ultraviolet emission in elves. The detector features modified Schmidt optics with large apertures resulting in a field of view that spans the horizon, and year‐round operation on dark nights with low moonlight background, when the local weather is favorable. The measured light profiles of 18% of the elve events have more than one peak, compatible with intracloud activity. Within the 3‐year s le, 72% of the elves correlate with the far‐field radiation measurements of the World Wide Lightning Location Network. The Auger Observatory plans to continue operations until at least 2025, including elve observations and analysis. To the best of our knowledge, this observatory is the only facility on Earth that measures elves with year‐round operation and full horizon coverage.
Publisher: IOP Publishing
Date: 07-2021
DOI: 10.1088/1748-0221/16/07/P07019
Abstract: The atmospheric depth of the air shower maximum X max is an observable commonly used for the determination of the nuclear mass composition of ultra-high energy cosmic rays. Direct measurements of X max are performed using observations of the longitudinal shower development with fluorescence telescopes. At the same time, several methods have been proposed for an indirect estimation of X max from the characteristics of the shower particles registered with surface detector arrays. In this paper, we present a deep neural network (DNN) for the estimation of X max . The reconstruction relies on the signals induced by shower particles in the ground based water-Cherenkov detectors of the Pierre Auger Observatory. The network architecture features recurrent long short-term memory layers to process the temporal structure of signals and hexagonal convolutions to exploit the symmetry of the surface detector array. We evaluate the performance of the network using air showers simulated with three different hadronic interaction models. Thereafter, we account for long-term detector effects and calibrate the reconstructed X max using fluorescence measurements. Finally, we show that the event-by-event resolution in the reconstruction of the shower maximum improves with increasing shower energy and reaches less than 25 g/cm 2 at energies above 2 × 10 19 eV.
Publisher: Informa UK Limited
Date: 2007
Publisher: IOP Publishing
Date: 25-01-2021
Publisher: IOP Publishing
Date: 07-2021
DOI: 10.1088/1748-0221/16/07/P07016
Abstract: The Pierre Auger Observatory, at present the largest cosmic-ray observatory ever built, is instrumented with a ground array of 1600 water-Cherenkov detectors, known as the Surface Detector (SD). The SD s les the secondary particle content (mostly photons, electrons, positrons and muons) of extensive air showers initiated by cosmic rays with energies ranging from 10 17 eV up to more than 10 20 eV. Measuring the independent contribution of the muon component to the total registered signal is crucial to enhance the capability of the Observatory to estimate the mass of the cosmic rays on an event-by-event basis. However, with the current design of the SD, it is difficult to straightforwardly separate the contributions of muons to the SD time traces from those of photons, electrons and positrons. In this paper, we present a method aimed at extracting the muon component of the time traces registered with each in idual detector of the SD using Recurrent Neural Networks. We derive the performances of the method by training the neural network on simulations, in which the muon and the electromagnetic components of the traces are known. We conclude this work showing the performance of this method on experimental data of the Pierre Auger Observatory. We find that our predictions agree with the parameterizations obtained by the AGASA collaboration to describe the lateral distributions of the electromagnetic and muonic components of extensive air showers.
Publisher: National Library of Serbia
Date: 2010
DOI: 10.2298/SAJ1081039A
Abstract: Cosmic rays travel at speeds essentially indistinguishable from the speed of light. However, whilst travelling through magnetic fields, both regular and turbulent, they are delayed behind the light since they are usually charged particles and their paths are not straight lines. Those delays can be so long that they are an impediment to correctly identifying sources, which may be variable in time. The magnitude of such delays will be discussed and compared to the characteristic time variation of possible cosmic ray sources.
Publisher: Elsevier BV
Date: 06-1999
Publisher: Elsevier BV
Date: 10-2001
Publisher: SPIE-Intl Soc Optical Eng
Date: 28-04-2015
Publisher: Elsevier BV
Date: 09-2016
Publisher: American Geophysical Union (AGU)
Date: 19-05-2016
DOI: 10.1002/2016JD025139
Publisher: Elsevier BV
Date: 07-2005
Publisher: Pleiades Publishing Ltd
Date: 11-2019
Publisher: Elsevier BV
Date: 06-1996
Publisher: Cambridge University Press (CUP)
Date: 2010
DOI: 10.1071/AS09077
Abstract: We review the importance of Centaurus A in high-energy astrophysics as a nearby object with many of the properties expected of a major source of very high-energy cosmic rays and gamma rays. We examine observational techniques and the results so far obtained in the energy range from 200 GeV to above 100 EeV and attempt to fit those data to expectations of Centaurus Aas an astrophysical source from very high to ultra-high energies.
Publisher: Jagiellonian University
Date: 2022
Publisher: IOP Publishing
Date: 27-09-2019
Publisher: EDP Sciences
Date: 22-11-2002
Publisher: Wiley
Date: 09-02-2013
DOI: 10.1002/JOC.3660
Publisher: American Astronomical Society
Date: 08-2022
Abstract: A promising energy range to look for angular correlations between cosmic rays of extragalactic origin and their sources is at the highest energies, above a few tens of EeV (1 EeV ≡ 10 18 eV). Despite the flux of these particles being extremely low, the area of ∼3000 km 2 covered at the Pierre Auger Observatory, and the 17 yr data-taking period of the Phase 1 of its operations, have enabled us to measure the arrival directions of more than 2600 ultra-high-energy cosmic rays above 32 EeV. We publish this data set, the largest available at such energies from an integrated exposure of 122,000 km 2 sr yr, and search it for anisotropies over the 3.4 π steradians covered with the Observatory. Evidence for a deviation in excess of isotropy at intermediate angular scales, with ∼15° Gaussian spread or ∼25° top-hat radius, is obtained at the 4 σ significance level for cosmic-ray energies above ∼40 EeV.
Publisher: American Astronomical Society
Date: 20-08-2001
DOI: 10.1086/322240
Publisher: Elsevier BV
Date: 06-2004
Publisher: IOP Publishing
Date: 07-1978
Publisher: American Astronomical Society
Date: 02-02-2018
Publisher: American Astronomical Society
Date: 04-2005
DOI: 10.1086/427931
Publisher: IOP Publishing
Date: 1981
Publisher: Cambridge University Press (CUP)
Date: 2000
DOI: 10.1071/AS00038
Abstract: Construction of the Pierre Auger Observatory for the study of the highest-energy cosmic rays is about to begin. Prior to the availability of data from that experiment, decisions should be made on techniques for the analysis of the directional properties of those data. We examine here one possible analysis tool, the two-point angular autocorrelation function. As a concrete ex le, data from the SUGAR array are examined in this way. Possible clustering of the data is observed, and the identification of such clustering with candidate astronomical objects in a purpose-developed catalogue is investigated.
Publisher: American Physical Society (APS)
Date: 19-11-1979
Publisher: CSIRO Publishing
Date: 1984
DOI: 10.1071/PH840097
Abstract: The knee of the cosmic:ray energy spectrum occurs at an energy slightly below 101 6 eV. At a similar energy significant changes are found in cosmic ray shower development and anisotropy. It is suggested that these changes can be understood if there is a general proton dominated cosmic ray flux along our spiral arm from outer galactic regions, which is exceeded by an iron dominated flux from the opposite spiral arm direction at energies between ~ 1014 and ~ 101 7 eV.
Publisher: Informa UK Limited
Date: 2006
Publisher: Springer Science and Business Media LLC
Date: 06-1984
DOI: 10.1038/309687A0
Publisher: Oxford University Press (OUP)
Date: 2003
DOI: 10.1143/PTPS.151.74
Publisher: CSIRO Publishing
Date: 1984
DOI: 10.1071/PH840091
Abstract: An analysis of recent data from the Adelaide cosmic ray shower array suggests that an excess of events may have been observed to come from the general direction of Centaurus A. These data are presented and discussed together with directional data from other previous experiments.
Publisher: Elsevier BV
Date: 05-2004
Publisher: American Astronomical Society
Date: 06-2004
DOI: 10.1086/383604
Publisher: Informa UK Limited
Date: 2009
Publisher: Elsevier BV
Date: 08-2011
Publisher: Scientific Scholar
Date: 2017
Publisher: EDP Sciences
Date: 09-2002
Publisher: IOP Publishing
Date: 07-1983
Publisher: American Astronomical Society
Date: 25-06-2004
DOI: 10.1086/423303
Publisher: Elsevier BV
Date: 11-2009
Publisher: IOP Publishing
Date: 06-2021
DOI: 10.1088/1748-0221/16/06/P06027
Abstract: FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Auger Observatory in Argentina for the purposes of atmospheric monitoring using stellar photometry. As a passive system which does not produce any light that could interfere with the observations of the fluorescence telescopes of the observatory, it complements the active monitoring systems that use lasers. We discuss the applications of stellar photometry for atmospheric monitoring at optical observatories in general and the particular modes of operation employed by the Auger FRAM. We describe in detail the technical aspects of FRAM, the hardware and software requirements for a successful operation of a robotic telescope for such a purpose and their implementation within the FRAM system.
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 08-1997
Publisher: EDP Sciences
Date: 14-04-2003
Publisher: Elsevier BV
Date: 03-2005
Publisher: Elsevier BV
Date: 07-1978
Publisher: IOP Publishing
Date: 23-09-2020
Publisher: Springer Science and Business Media LLC
Date: 1970
DOI: 10.1038/225253A0
Publisher: Cambridge University Press (CUP)
Date: 2000
DOI: 10.1071/AS00040
Abstract: There is now evidence that there may be a strong source of cosmic ray particles in the general direction of the Galactic Centre. The likelihood is that the observed particles are neutrons with energies of about 10 18 eV. Associated with the production of those neutrons, we would expect that large numbers of charged cosmic rays would also be produced, and we investigate here the directional properties of those charged particles as they may be observed at the distance of the Earth from the Galactic Centre. We follow the propagation of such particles through a simple Galactic magnetic field model with both a turbulent and a regular field to determine what field properties most affect the observed beam. It appears that the turbulent field component is crucial to any resulting charged particle observations.
Publisher: IOP Publishing
Date: 19-03-2002
Publisher: IOP Publishing
Date: 08-1979
Publisher: CSIRO Publishing
Date: 1984
DOI: 10.1071/PH840309
Abstract: A study has been made of a recently suggested scheme for the economical detection and analysis of ultra-high energy cosmic ray showers. It is demonstrated that the scheme should be feasible, particularly if detectors are used to s le the y-ray component of the showers.
Publisher: CSIRO Publishing
Date: 1982
DOI: 10.1071/PH820441
Abstract: The declination isotropy of cosmic ray showers of energies of about 10'6 eV is studied using data from the Buckland Park extensive air shower (EAS) array and compared with measurements available through an analysis of data in the literature. It appears that an upper limit can be set to the anisotropy in declination at this energy of ~ 3, 5 %, limited by timing uncertainties in array directional measurements
Publisher: Elsevier BV
Date: 04-2004
Publisher: SAGE Publications
Date: 21-04-2023
DOI: 10.1177/21677026231164393
Abstract: Although emotion dysregulation has been robustly associated with posttraumatic stress disorder (PTSD), there is relatively little understanding of this process in refugees. Specifically, longitudinal methodology has not been used to examine the relationship between emotion dysregulation and PTSD among refugees. In this study, we investigated the temporal relationship between emotion dysregulation, postmigration stressors, and PTSD clusters (reexperiencing, avoidance, negative alterations in mood and cognition [NAMC], and hyperarousal) from the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders among a community s le of refugees ( N = 1,081) over a 2-year period. Random intercept cross-lagged panel analysis found that emotion dysregulation was antecedent to within-persons increases in reexperiencing and NAMC symptoms over time and bidirectionally associated with hyperarousal and postmigration stressors. In addition, postmigration stressors were antecedent to within-persons increases in reexperiencing, avoidance, and NAMC and bidirectionally associated with hyperarousal symptoms. Findings provide novel evidence in support of postmigration stressors and emotion dysregulation as mechanisms maintaining PTSD and highlight the potential utility of tailoring interventions to address these factors.
Publisher: Springer Science and Business Media LLC
Date: 03-1974
DOI: 10.1038/248028A0
Publisher: Cambridge University Press (CUP)
Date: 1998
DOI: 10.1071/AS98208
Abstract: Measurements of cosmic ray directional properties at about 10 15 eV in both northern and southern hemispheres confirm that those particles have a unidirectional anisotropy and are flowing along the direction of our spiral arm from the inner Galactic regions. On the basis of diffusive cosmic ray flow along the Galactic arms, the power required for the Galaxy to maintain this flow is below 10 30 W.
Publisher: arXiv
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 11-1986
DOI: 10.1007/BF02507429
Publisher: Wiley
Date: 11-12-2009
DOI: 10.1002/MET.168
Publisher: Cambridge University Press (CUP)
Date: 1998
DOI: 10.1071/AS98332
Abstract: A cloud monitor has been developed for use with cosmic ray air shower fluorescence detectors, the High Resolution Fly's Eye and the Pierre Auger Observatory. This is based on an infrared thermopile device which, unlike previous such monitors, requires no moving chopper and is suitable for unattended operation over long periods of time.
Publisher: American Astronomical Society
Date: 10-04-2005
DOI: 10.1086/428570
Publisher: American Astronomical Society
Date: 10-02-2006
DOI: 10.1086/498858
Publisher: Cambridge University Press (CUP)
Date: 2004
DOI: 10.1071/AS03047
Abstract: Cosmic rays with energies above 10 18 eV are currently of considerable interest in astrophysics and are to be further studied in a number of projects which are either currently under construction or the subject of well-developed proposals. This paper aims to discuss some of the physics of such particles in terms of current knowledge and information from particle astrophysics at other energies.
Publisher: Cambridge University Press (CUP)
Date: 2000
DOI: 10.1071/AS00171
Abstract: Practical astronomy is usually taught using optical telescopes or, more rarely, radio telescopes. For a similar cost, complementary studies may be made of astrophysical particles through the use of a modestly sized muon detector. Such a detector records the arrival of cosmic ray particles that have traversed the heliosphere and the rate of muon detections reflects the flux of those particles. That flux is controlled by the day to day properties of the heliosphere which is in a state of constant change as the outflowing solar wind is affected by solar activity. As a consequence, a laboratory muon detector, whose count rate depends on the state of the heliosphere, can be an interesting and useful teaching tool that is complementary to optical or radio studies of the Sun.
Publisher: IOP Publishing
Date: 06-1989
Publisher: Elsevier BV
Date: 04-2001
Publisher: Elsevier BV
Date: 10-2017
Publisher: Springer Science and Business Media LLC
Date: 09-1970
DOI: 10.1038/2271116A0
Publisher: Springer Science and Business Media LLC
Date: 09-1995
DOI: 10.1007/BF00658641
Publisher: American Astronomical Society
Date: 02-06-2003
DOI: 10.1086/376978
Publisher: Springer Science and Business Media LLC
Date: 07-1991
DOI: 10.1038/352132A0
Publisher: Elsevier BV
Date: 09-2009
Publisher: Informa UK Limited
Date: 10-2010
Publisher: Elsevier BV
Date: 03-2003
Publisher: Cambridge University Press (CUP)
Date: 1997
DOI: 10.1071/AS97258
Abstract: The propagation of the highest energy cosmic rays through the 2·7 K microwave background is considered. Photo-pion production interactions cause energy losses for primary cosmic ray protons which result in significant energy degradation over intergalactic distances. The process of energy loss is discussed and an estimate is made of the average distances travelled for observed cosmic rays with a range of energies, assuming a power law source spectrum. At energies over 10 20 eV, the average distances travelled are a few tens of megaparsecs, limiting possible sources to the volume dominated by the supergalactic plane.
Publisher: American Astronomical Society
Date: 07-2022
Abstract: Ultra-high-energy photons with energies exceeding 10 17 eV offer a wealth of connections to different aspects of cosmic-ray astrophysics as well as to gamma-ray and neutrino astronomy. The recent observations of photons with energies in the 10 15 eV range further motivate searches for even higher-energy photons. In this paper, we present a search for photons with energies exceeding 2 × 10 17 eV using about 5.5 yr of hybrid data from the low-energy extensions of the Pierre Auger Observatory. The upper limits on the integral photon flux derived here are the most stringent ones to date in the energy region between 10 17 and 10 18 eV.
Publisher: Elsevier BV
Date: 06-1972
Publisher: Cambridge University Press (CUP)
Date: 2001
DOI: 10.1071/AS01032
Abstract: Cosmic ray arrival directions at energies a little over 10 18 eV have been reported to show an excess from directions close to that of the Galactic centre. That result was originally presented by the AGASA group and was later strengthened by an analysis of SUGAR cosmic ray data. We discuss here a second feature of the AGASA data, a deficit in roughly the Galactic anticentre direction.We interpret this as a result of cosmic ray diffusion past us. We find that the most straightforward interpretation of the data then requires that a strong magnetic field exists out of the plane of our Galaxy to distances of at least several kiloparsecs.
Publisher: Springer Science and Business Media LLC
Date: 05-1985
DOI: 10.1038/315205A0
Publisher: American Astronomical Society
Date: 08-2022
Abstract: For several decades, the origin of ultra-high-energy cosmic rays (UHECRs) has been an unsolved question of high-energy astrophysics. One approach for solving this puzzle is to correlate UHECRs with high-energy neutrinos, since neutrinos are a direct probe of hadronic interactions of cosmic rays and are not deflected by magnetic fields. In this paper, we present three different approaches for correlating the arrival directions of neutrinos with the arrival directions of UHECRs. The neutrino data are provided by the IceCube Neutrino Observatory and ANTARES, while the UHECR data with energies above ∼50 EeV are provided by the Pierre Auger Observatory and the Telescope Array. All experiments provide increased statistics and improved reconstructions with respect to our previous results reported in 2015. The first analysis uses a high-statistics neutrino s le optimized for point-source searches to search for excesses of neutrino clustering in the vicinity of UHECR directions. The second analysis searches for an excess of UHECRs in the direction of the highest-energy neutrinos. The third analysis searches for an excess of pairs of UHECRs and highest-energy neutrinos on different angular scales. None of the analyses have found a significant excess, and previously reported overfluctuations are reduced in significance. Based on these results, we further constrain the neutrino flux spatially correlated with UHECRs.
Publisher: American Physical Society (APS)
Date: 16-07-2018
Publisher: Springer Science and Business Media LLC
Date: 11-1981
DOI: 10.1007/BF02507991
Publisher: Elsevier BV
Date: 03-2020
Publisher: Springer Science and Business Media LLC
Date: 04-1982
DOI: 10.1007/BF00648560
Publisher: Zenodo
Date: 2018
Publisher: No publisher found
Date: 1981
Publisher: IOP Publishing
Date: 09-1984
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: Elsevier BV
Date: 02-1981
Publisher: Springer Science and Business Media LLC
Date: 09-1973
DOI: 10.1038/245086A0
Publisher: IOP Publishing
Date: 08-1981
Publisher: arXiv
Date: 2022
Publisher: IOP Publishing
Date: 06-1988
Publisher: American Astronomical Society
Date: 05-01-2005
DOI: 10.1086/427980
Publisher: American Physical Society (APS)
Date: 15-04-2004
Publisher: Elsevier BV
Date: 12-2002
Publisher: Elsevier BV
Date: 10-1998
Publisher: IOP Publishing
Date: 10-1983
Publisher: Elsevier BV
Date: 2000
Publisher: IOP Publishing
Date: 1977
Publisher: IOP Publishing
Date: 07-2021
DOI: 10.1088/1748-0221/16/07/T07008
Abstract: The Auger Muon Infill Ground Array (AMIGA) is part of the AugerPrime upgrade of the Pierre Auger Observatory. It consists of particle counters buried 2.3 m underground next to the water-Cherenkov stations that form the 23.5 km 2 large infilled array. The reduced distance between detectors in this denser area allows the lowering of the energy threshold for primary cosmic ray reconstruction down to about 10 17 eV. At the depth of 2.3 m the electromagnetic component of cosmic ray showers is almost entirely absorbed so that the buried scintillators provide an independent and direct measurement of the air showers muon content. This work describes the design and implementation of the AMIGA embedded system, which provides centralized control, data acquisition and environment monitoring to its detectors. The presented system was firstly tested in the engineering array phase ended in 2017, and lately selected as the final design to be installed in all new detectors of the production phase. The system was proven to be robust and reliable and has worked in a stable manner since its first deployment.
Publisher: Elsevier BV
Date: 11-1999
Publisher: EDP Sciences
Date: 11-10-2006
Publisher: Elsevier BV
Date: 08-2000
Publisher: American Physical Society (APS)
Date: 08-05-2000
Publisher: IOP Publishing
Date: 09-1978
Publisher: IOP Publishing
Date: 03-09-2020
Publisher: Elsevier BV
Date: 05-2004
Publisher: American Physical Society (APS)
Date: 16-09-2020
Publisher: IOP Publishing
Date: 1993
Publisher: IOP Publishing
Date: 04-2021
DOI: 10.1088/1748-0221/16/04/P04003
Abstract: To obtain direct measurements of the muon content of extensive air showers with energy above 10 16.5 eV, the Pierre Auger Observatory is currently being equipped with an underground muon detector (UMD), consisting of 219 10 m 2 -modules, each segmented into 64 scintillators coupled to silicon photomultipliers (SiPMs). Direct access to the shower muon content allows for the study of both of the composition of primary cosmic rays and of high-energy hadronic interactions in the forward direction. As the muon density can vary between tens of muons per m 2 close to the intersection of the shower axis with the ground to much less than one per m 2 when far away, the necessary broad dynamic range is achieved by the simultaneous implementation of two acquisition modes in the read-out electronics: the binary mode, tuned to count single muons, and the ADC mode, suited to measure a high number of them. In this work, we present the end-to-end calibration of the muon detector modules: first, the SiPMs are calibrated by means of the binary channel, and then, the ADC channel is calibrated using atmospheric muons, detected in parallel to the shower data acquisition. The laboratory and field measurements performed to develop the implementation of the full calibration chain of both binary and ADC channels are presented and discussed. The calibration procedure is reliable to work with the high amount of channels in the UMD, which will be operated continuously, in changing environmental conditions, for several years.
Publisher: American Astronomical Society
Date: 02-2023
Abstract: A catalog containing details of the highest-energy cosmic rays recorded through the detection of extensive air showers at the Pierre Auger Observatory is presented with the aim of opening the data to detailed examination. Descriptions of the 100 showers created by the highest-energy particles recorded between 2004 January 1 and 2020 December 31 are given for cosmic rays that have energies in the range 78–166 EeV. Details are also given on a further nine very energetic events that have been used in the calibration procedure adopted to determine the energy of each primary. A sky plot of the arrival directions of the most energetic particles is shown. No interpretations of the data are offered.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 22-09-2017
Abstract: Cosmic rays are high-energy particles arriving from space some have energies far beyond those that human-made particle accelerators can achieve. The sources of higher-energy cosmic rays remain under debate, although we know that lower-energy cosmic rays come from the solar wind. The Pierre Auger Collaboration reports the observation of thousands of cosmic rays with ultrahigh energies of several exa–electron volts (about a Joule per particle), arriving in a slightly dipolar distribution (see the Perspective by Gallagher and Halzen). The direction of the rays indicates that the particles originated in other galaxies and not from nearby sources within our own Milky Way Galaxy. Science , this issue p. 1266 see also p. 1240
Publisher: American Astronomical Society
Date: 09-04-2004
DOI: 10.1086/421292
Publisher: American Astronomical Society
Date: 13-03-2020
Publisher: IOP Publishing
Date: 16-10-2017
Publisher: Elsevier BV
Date: 2020
Publisher: CSIRO Publishing
Date: 1997
DOI: 10.1071/P96066
Abstract: A small cosmic ray extensive air shower (EAS) array for anisotropy studies has been built and operated in the southern hemisphere for a full year. The operation of such an array is discussed as a possible prototype for a multiarray system which would be simple and reliable to operate. Data from the array are presented to add to the sparse southern hemisphere data set below energies of about 1 PeV.
Publisher: IOP Publishing
Date: 07-1980
Publisher: Springer Science and Business Media LLC
Date: 08-2020
DOI: 10.1140/EPJC/S10052-020-8055-Y
Abstract: The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between $$2\\times 10^{17}$$ 2 × 10 17 and $$2\\times 10^{18}$$ 2 × 10 18 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at $$10^{{17.5}}\\, {\\mathrm{eV}} $$ 10 17.5 eV and $$10^{{18}}\\, {\\mathrm{eV}} $$ 10 18 eV . We find that, for the models to explain the data, an increase in the muon density of $$38\\%$$ 38 % $$\\pm 4\\% (12\\%)$$ ± 4 % ( 12 % ) $$\\pm {}^{21\\%}_{18\\%}$$ ± 18 % 21 % for EPOS-LHC , and of $$50\\% (53\\%)$$ 50 % ( 53 % ) $$\\pm 4\\% (13\\%)$$ ± 4 % ( 13 % ) $$\\pm {}^{23\\%}_{20\\%}$$ ± 20 % 23 % for QGSJetII-04 , is respectively needed.
Publisher: SAGE Publications
Date: 02-1999
Publisher: MDPI AG
Date: 03-2022
DOI: 10.3390/SYM14030501
Abstract: The Cosmic Ray Extremely Distributed Observatory (CREDO) pursues a global research strategy dedicated to the search for correlated cosmic rays, so-called Cosmic Ray Ensembles (CRE). Its general approach to CRE detection does not involve any a priori considerations, and its search strategy encompasses both spatial and temporal correlations, on different scales. Here we search for time clustering of the cosmic ray events collected with a small sea-level extensive air shower array at the University of Adelaide. The array consists of seven one-square-metre scintillators enclosing an area of 10 m × 19 m. It has a threshold energy ~0.1 PeV, and records cosmic ray showers at a rate of ~6 mHz. We have examined event arrival times over a period of over 2.5 years in two equipment configurations (without and with GPS timing), recording ~300 k events and ~100 k events. We determined the event time spacing distributions between in idual events and the distributions of time periods which contained specific numbers of multiple events. We find that the overall time distributions are as expected for random events. The distribution which was chosen a priori for particular study was for time periods covering five events (four spacings). Overall, these distributions fit closely with expectation, but there are two outliers of short burst periods in data for each configuration. One of these outliers contains eight events within 48 s. The physical characteristics of the array will be discussed together with the analysis procedure, including a comparison between the observed time distributions and expectation based on randomly arriving events.
Publisher: American Physical Society (APS)
Date: 16-04-2021
Publisher: IOP Publishing
Date: 07-03-2019
Publisher: American Physical Society (APS)
Date: 05-1981
Publisher: IOP Publishing
Date: 12-1995
Publisher: American Physical Society (APS)
Date: 16-09-2020
Publisher: American Astronomical Society
Date: 10-2020
Abstract: Results of a search for ultra-high-energy neutrinos with the Pierre Auger Observatory from the direction of the blazar TXS 0506+056 are presented. They were obtained as part of the follow-up that stemmed from the detection of high-energy neutrinos and gamma rays with IceCube, Fermi-LAT, MAGIC, and other detectors of electromagnetic radiation in several bands. The Pierre Auger Observatory is sensitive to neutrinos in the energy range from 100 PeV to 100 EeV and in the zenith-angle range from θ = 60° to θ = 95°, where the zenith angle is measured from the vertical direction. No neutrinos from the direction of TXS 0506+056 have been found. The results were analyzed in three periods: one of 6 months around the detection of IceCube-170922 A, coinciding with a flare period of TXS 0506+056, a second one of 110 days during which the IceCube collaboration found an excess of 13 neutrinos from a direction compatible with TXS 0506+056, and a third one from 2004 January 1 up to 2018 August 31, over which the Pierre Auger Observatory has been taking data. The sensitivity of the Observatory is addressed for different spectral indices by considering the fluxes that would induce a single expected event during the observation period. For indices compatible with those measured by the IceCube collaboration the expected number of neutrinos at the Observatory is well below one. Spectral indices as hard as 1.5 would have to apply in this energy range to expect a single event to have been detected.
Publisher: Elsevier BV
Date: 11-1992
Publisher: Springer Science and Business Media LLC
Date: 1981
DOI: 10.1007/BF02507744
Publisher: Cambridge University Press (CUP)
Date: 2002
DOI: 10.1071/AS01064
Abstract: An examination is made of the relationship between the observed energy spectrum of cosmic rays and the averaged spectrum of the cosmic rays at their sources. These spectra differ greatly, due to propagation effects. A form of the source spectrum is deduced which is a rather featureless power law over the full range of observations from 10 10 eV to 10 20 eV. We suggest that this lack of features is indicative of a common source for all cosmic rays over the full energy range, as opposed to lower energy Galactic and higher energy intergalactic components such as is often suggested.
Publisher: IOP Publishing
Date: 21-10-2020
Publisher: arXiv
Date: 2022
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 07-2003
End Date: 12-2006
Amount: $300,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2001
End Date: 12-2002
Amount: $220,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2003
End Date: 12-2006
Amount: $328,035.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2008
End Date: 12-2012
Amount: $520,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2020
End Date: 12-2024
Amount: $570,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2015
End Date: 06-2020
Amount: $694,300.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 12-2018
Amount: $159,450.00
Funder: Australian Research Council
View Funded Activity