Related papers: Cosmic-ray energy spectrum and composition up to t…
The all-particle spectrum of cosmic rays measured at Earth has a knee-like feature around 4 PeV. A priori, it is not clear if this is a local feature specific to the Solar neighbourhood in the Milky Way, or if it is a generic property of…
The signatures of UHE proton propagation through CMB are pair-production dip and GZK cutoff. The visible manifestations of these spectral features are ankle, beginning of GZK cutoff in the differential spectrum and E_{1/2} in integral…
We have measured the cosmic ray spectrum at energies above $10^{17}$ eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric…
It has recently been suggested that ultra-high energy cosmic rays could have an extragalactic origin down to the "second knee" at ~4x10^{17}eV. In this case the "ankle" or "dip" at ~5x10^{18}eV would be due to pair production of…
Several kinds of measurements are combined in an attempt to obtain a consistent estimate of the spectrum and composition of the primary cosmic radiation through the knee region. Assuming that the knee is a signal of the high-energy end of a…
We examine the question of the origin of the Galactic cosmic-rays (GCRs) in the light of the data available at the highest energy end of the spectrum. We argue that the data of the Pierre Auger Observatory and of the KASCADE-Grande…
One prediction of particle acceleration in the supernova remnants in the magnetic wind of exploding Wolf Rayet and Red Super Giant stars is that the final spectrum is a composition of a spectrum $E^{-7/3}$ and a polar cap component of…
The differential intensity of cosmic radiation shows a sequence of depressions referred to as "knees" in a large energy band above 10^15 eV. The global depression entailed in the complete spectrum with respect to the extrapolated intensity…
The mass composition of high energy cosmic rays depends on their production, acceleration, and propagation. The study of cosmic ray composition can therefore reveal hints of the origin of these particles. At the South Pole, the IceCube…
We consider the possibility of explaining the observed spectrum and composition of the cosmic rays with energies above $10^{17}$ eV in terms of two different extragalactic populations of sources in the presence of a turbulent intergalactic…
The origin of cosmic rays above the knee in the spectrum is an unsolved problem. We present a wind model in which interstellar gas flows along a non-rotating, expanding flux tube with a changing speed and cross-sectional area. Cosmic rays…
The accurate determination of the elemental composition of cosmic rays at high energies is expected to provide crucial clues on the origin of these particles. Previous direct measurements of composition have been limited by experiment…
Primary cosmic ray particles above energies of about 100 TeV are investigated by large-area ground based detector installations, observing various components of the development of extensive air-showers (EAS). By such an indirect access to…
Recent results of the KASCADE-Grande experiment provided evidence for a mild knee-like structure in the all-particle spectrum of cosmic rays at $E = 10^{16.92 \pm 0.10} \, \mathrm{eV}$, which was found to be due to a steepening in the flux…
We discuss the differences induced by the assumed composition of extragalactic sources on the predicted UHECR spectrum and the energy evolution of $<X_{\max}>$, i.e. the mean value of the atmospheric depth at the cosmic-ray air shower…
The small change in the spectral slope of the overall intensity of cosmic rays near 1 PeV may be associated with the endpoint energy of supernova shock acceleration. A crucial test of this connection and other ideas of the origin of the…
We present a complete phenomenological model accounting for the evolution of the cosmic-ray spectrum and composition with energy, based on the available data over the entire spectrum. We show that there is no need to postulate any…
The search for a theory of the origin of cosmic rays that may be considered as a standard, agreeable model is still ongoing. On one hand, much circumstantial evidence exists of the fact that supernovae in our Galaxy play a crucial role in…
Cosmic ray (CR) knees (spectral steepenings) encode information on CR accelerator populations. We seek population features that imprint onto knee observables in a manner that is robust enough to be discernible even in the presence of…
In the common model supernova shock-acceleration of cosmic rays there are two open questions: 1. where does the high energy cosmic rays below the knee (10$^4-10^6$ Gev) come from, and 2. are cosmic ray accelerated only at their origin or…