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Evidence for a Mixed Mass Composition at the 'ankle' in the Cosmic-ray Spectrum

Evidence for a Mixed Mass Composition at the 'ankle' in the Cosmic-ray Spectrum PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

Book Description
Here, we report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at $\lg(E/{\rm eV})=18.5-19.0$ differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass $A> 4$. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.

Evidence for a Mixed Mass Composition at the 'ankle' in the Cosmic-ray Spectrum

Evidence for a Mixed Mass Composition at the 'ankle' in the Cosmic-ray Spectrum PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

Book Description
Here, we report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at $\lg(E/{\rm eV})=18.5-19.0$ differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass $A> 4$. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.

Origin of Cosmic Rays

Origin of Cosmic Rays PDF Author: Vitaliĭ Lazarevich Ginzburg
Publisher:
ISBN:
Category :
Languages : en
Pages : 62

Book Description


Dark Matter

Dark Matter PDF Author: Michael Smith
Publisher: BoD – Books on Demand
ISBN: 183962440X
Category : Science
Languages : en
Pages : 136

Book Description
This book presents several new, important explanations for dark matter, all dissimilar to the discredited subatomic particle-like but invisible matter. One chapter presents evidence that abundant cold hydrogen, baryonic matter, is the source of the missing gravity. Another chapter suggests that dark matter is better explained by stars in spiral galaxies that follow non-Keplerian orbits. A third chapter proposes that gravity attributed to dark matter is due to the sprinkling of black holes throughout galaxies, which is supported by LIGO/Virgo observations. Another chapter questions the assumptions of the Friedmann (FLRW) model, proposing a better method for handling astrophysical data. Additional chapters discuss cosmic ray propagation, axion decay, the cosmological scale factor, and the philosophical outlook of cosmologists when dealing with the questions of dark matter and dark energy.

Cosmic Rays at the Ankle

Cosmic Rays at the Ankle PDF Author: Patrick William Younk
Publisher:
ISBN:
Category :
Languages : en
Pages : 149

Book Description


Cosmic Rays at Earth

Cosmic Rays at Earth PDF Author: P.K.F. Grieder
Publisher: Elsevier
ISBN: 0080530052
Category : Science
Languages : en
Pages : 1117

Book Description
In 1912 Victor Franz Hess made the revolutionary discovery that ionizing radiation is incident upon the Earth from outer space. He showed with ground-based and balloon-borne detectors that the intensity of the radiation did not change significantly between day and night. Consequently, the sun could not be regarded as the sources of this radiation and the question of its origin remained unanswered. Today, almost one hundred years later the question of the origin of the cosmic radiation still remains a mystery.Hess' discovery has given an enormous impetus to large areas of science, in particular to physics, and has played a major role in the formation of our current understanding of universal evolution. For example, the development of new fields of research such as elementary particle physics, modern astrophysics and cosmology are direct consequences of this discovery. Over the years the field of cosmic ray research has evolved in various directions: Firstly, the field of particle physics that was initiated by the discovery of many so-called elementary particles in the cosmic radiation. There is a strong trend from the accelerator physics community to reenter the field of cosmic ray physics, now under the name of astroparticle physics. Secondly, an important branch of cosmic ray physics that has rapidly evolved in conjunction with space exploration concerns the low energy portion of the cosmic ray spectrum. Thirdly, the branch of research that is concerned with the origin, acceleration and propagation of the cosmic radiation represents a great challenge for astrophysics, astronomy and cosmology. Presently very popular fields of research have rapidly evolved, such as high-energy gamma ray and neutrino astronomy. In addition, high-energy neutrino astronomy may soon initiate as a likely spin-off neutrino tomography of the Earth and thus open a unique new branch of geophysical research of the interior of the Earth. Finally, of considerable interest are the biological and medical aspects of the cosmic radiation because of it ionizing character and the inevitable irradiation to which we are exposed. This book is a reference manual for researchers and students of cosmic ray physics and associated fields and phenomena. It is not intended to be a tutorial. However, the book contains an adequate amount of background materials that its content should be useful to a broad community of scientists and professionals. The present book contains chiefly a data collection in compact form that covers the cosmic radiation in the vicinity of the Earth, in the Earth's atmosphere, at sea level and underground. Included are predominantly experimental but also theoretical data. In addition the book contains related data, definitions and important relations. The aim of this book is to offer the reader in a single volume a readily available comprehensive set of data that will save him the need of frequent time consuming literature searches.

Handbook of Particle Detection and Imaging

Handbook of Particle Detection and Imaging PDF Author: Claus Grupen
Publisher: Springer Science & Business Media
ISBN: 3642132715
Category : Science
Languages : en
Pages : 1251

Book Description
The handbook centers on detection techniques in the field of particle physics, medical imaging and related subjects. It is structured into three parts. The first one is dealing with basic ideas of particle detectors, followed by applications of these devices in high energy physics and other fields. In the last part the large field of medical imaging using similar detection techniques is described. The different chapters of the book are written by world experts in their field. Clear instructions on the detection techniques and principles in terms of relevant operation parameters for scientists and graduate students are given.Detailed tables and diagrams will make this a very useful handbook for the application of these techniques in many different fields like physics, medicine, biology and other areas of natural science.

High Energy Cosmic Rays

High Energy Cosmic Rays PDF Author: Todor Stanev
Publisher: Springer Science & Business Media
ISBN: 3540851488
Category : Science
Languages : en
Pages : 334

Book Description
Offers an accessible text and reference (a cosmic-ray manual) for graduate students entering the field and high-energy astrophysicists will find this an accessible cosmic-ray manual Easy to read for the general astronomer, the first part describes the standard model of cosmic rays based on our understanding of modern particle physics. Presents the acceleration scenario in some detail in supernovae explosions as well as in the passage of cosmic rays through the Galaxy. Compares experimental data in the atmosphere as well as underground are compared with theoretical models

A Study of the Ultrahigh-energy Cosmic Ray Mass Composition with the MACRO and EAS-TOP Experiments [microform]

A Study of the Ultrahigh-energy Cosmic Ray Mass Composition with the MACRO and EAS-TOP Experiments [microform] PDF Author: Coutu, Stéphane
Publisher: Ann Arbor, Mich. : University Microfilms International
ISBN:
Category :
Languages : en
Pages : 374

Book Description


Towards a New Cosmic Ray Composition Measurement in the Knee

Towards a New Cosmic Ray Composition Measurement in the Knee PDF Author: Scott Patrick Wakely
Publisher:
ISBN:
Category :
Languages : en
Pages : 296

Book Description


Exporation of a Novel Technique to Measure the Mass Composition of Cosmic Rays with Energies Above 10[sup]19 EV

Exporation of a Novel Technique to Measure the Mass Composition of Cosmic Rays with Energies Above 10[sup]19 EV PDF Author: Maria Marchesini
Publisher:
ISBN:
Category :
Languages : en
Pages : 207

Book Description