Overview on direct and indirect measurements of cosmic rays - Some thoughts on galactic cosmic rays and the knee

An overview is given on results from direct and indirect measurements of galactic cosmic rays. Their implications on the contemporary understanding of the origin of cosmic rays and the knee in their energy spectrum are discussed.Comment: Invited overview, presented at the 19th European Cosmic Ray Symposium, August 30th - September 3rd, 2004, Florence, Ital

Measurement of radio emission from extensive air showers

A new promising development in astroparticle physics is to measure the radio emission from extensive air showers. The particles in the cascade emit synchrotron radiation (30 - 90 MHz) which is detected with arrays of dipole antennas. Recent experimental efforts are discussed.Comment: invited review at 11th ICATP

A new method to search for a cosmic ray dipole anisotropy

We propose a new method to determine the dipole (and quadrupole) component of a distribution of cosmic ray arrival directions, which can be applied when there is partial sky coverage and/or inhomogeneous exposure. In its simplest version it requires that the exposure only depends on the declination, but it can be easily extended to the case of a small amplitude modulation in right ascension. The method essentially combines a $\chi^2$ minimization of the distribution in declination to obtain the multipolar components along the North-South axis and a harmonic Rayleigh analysis for the components involving the right ascension direction

The knee in galactic cosmic ray spectrum and variety in supernovae

The present paper deals with calculations based on a standard model of cosmic ray acceleration in Supernova remnants (SNR) and on the latest astronomical data concerning the variety in Supernovae types, energies as well as the sites of their explosions. The results obtained allow explaination of the main features of all particle cosmic ray spectrum, including the 'knee'. This conclusion is based essentially on the premise that energy of accelerated CR in the given SNR is proportional to the kinetic energy of this explosion, that stresses the input of high energy explosions and suppresses the contribution of low energy explosions to the total CR flux.Comment: LaTeX2e, 18 pages with 9 figures in eps forma

Enhancing the Pierre Auger Observatory to the 10^{17} to 10^{18.5} eV Range: Capabilities of an Infill Surface Array

The Pierre Auger Observatory has been designed to study the highest-energy cosmic rays in nature (E > 10^{18.5} eV). The determination of their arrival direction, energy and composition is performed by the analysis of the atmospheric showers they produce. The Auger Surface Array will consist of 1600 water Cerenkov detectors placed in an equilateral triangular grid of 1.5 km spacing. The aim of this paper is to show that the addition of a "small" area of surface detectors at half or less the above mentioned spacing would allow a dramatic increase of the physical scope of this Observatory, reaching lower energies at which the transition from galactic to extragalactic sources is expected.Comment: 21 pages, 5 figures, accepted for publication in Nucl. Instr. & Meth. in Phys. Res.