New aspects in nucleon-nucleus collisions and EAS properties around 10(6) GeV

At energies higher than 2 x 10 to the 5 GeV, very little information exists on detailed properties of nucleon-nucleon collision; the rare elements are coming from jets, and, as nondirect improvements from gamma-ray families. The results exhibit some conflicting features, or, at least, very large fluctuations like copious production of gamma-rays in opposition to Centauro-like events, sometimes suggest that phase transition to quark gluon plasma occurs in nucleus-nucleus collisions and even in nucleon-nucleus collision. The multicluster phenomenological model (MPM) extrapolated for extensive air showers EAS simulation up to 5 x 10 to the 6 GeV to put in evidence some significant deviation between experimental data and prediction

Topological aspects of age parameter

The well known NKG function is a very useful tool to describe the lateral extension of the electromagnetic component in Extensive Air Showers (EAS); however, in spite of non-negligible qualities (simplicity, normalization by beta function), it doesn't correspond exactly to the natural shape of the lateral electron distribution. Several bias may occur in size estimation if NKG is used without correction. It is shown that the longitudinal age parameter s sub t can be correlated with the information obtained from the lateral electron densities according to the conditions of use of the NKG function

LPM effect and primary energy estimations

The distortion of the electron cascade development under LPM effects is now admitted; it consists of an increase of depth of showers origin, of shower maximum T sum max, a decrease of the number of particles at maximum N sub max and results in a flattening and a widening of the cascade transition curve. Connected with the influence of multiple Coulomb scattering on basic electromagnetic processes (bremsstrahlung, pair production), this effect appears at high energy with a threshold dependent on the density of the medium (more than 10 TeV for lead, more than 10 sup 6 TeV in air). Consequently, the electromagnetic components of hadron induced showers in lead and EAS in air calculated for the same hadronic cascades in the different alternative, including or not the LPM effect are examined here

Behaviour of the EAS Age Parameter in the Knee Energy Region

Analyzing simulated EAS events generated with the CORSIKA code, the characteristics of lateral distribution of electrons in EAS around the knee energy region of the primary energy spectrum have been studied and compared with experimental observations. The differences between the EGS4 and the NKG output of CORSIKA in respect to electron radial density distribution have been investigated. The relation between lateral and longitudinal age parameters has been studied after introducing the notion of the local age parameter that reflects the profile of the lateral distribution of electrons in EAS. The present analysis motivates the inclusion of the lateral shower age in a multiparameter study of EAS to extract information on hadronic interactions and primary composition.Comment: Talk presented at XVI International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI 2010), Batavia, IL, USA (28 June - 2 July 2010). 4 pages, 5 figure

The concept os habitus: "with Bourdieu and against Bourdieu"

Este texto analiza las fortalezas y límites explicativos del concepto de habitus en el estructuralismo genético de Pierre Bourdieu. Para lo que tomamos los aportes de diversos autores que han centrado su mirada en dicho concepto (Corcuff, 2005; Baranger, 2004; Costa, 2006). El artículo, de este modo, da cuenta de las distintas facetas del habitus en la teoría de Bourdieu. Con este concepto el autor busca superar la falsa dicotomía entre objetivismo y subjetivismo. La dimensión de lo colectivo que el habitus captura constituye asimismo otra de sus fortalezas explicativas, abordadas a lo largo del trabajo. A su vez, la potencialidad explicativa del habitus cobra fuerza cuando da cuenta del proceso de conformación y continuidad de las disposiciones de los agentes. Sin embargo la manera de plantear la relación entre las estructuras objetivas y el habitus, desdibuja el papel activo del agente para transformar sus propias disposiciones. De manera que el concepto de habitus se confirma como un punto de apoyo para explicar la continuidad de las disposiciones pero, al mismo tiempo, como un concepto insuficiente para captar el proceso de transformación de las distintas facetas de la singularidad.This article analyzes the strengths and limits that explain the concept of habitus in Pierre Bourdieu’s genetic structuralism. To do so, we include the contributions of several authors who have focused their work on such concept (Corcuff, 2005; Baranger, 2004; Costa, 2006). In this way, the article goes through the different aspects of habitus in Bourdieu’s theory. With this concept the author seeks to overcome the false dichotomy between objectivism and subjectivism. The dimension of collective action implied by habitus is, in itself, another of its strengths, addressed throughout the work. In turn, the explanatory potential of habitus is reinforced by its clarification of the process of formation and continuation of the provisions of the agents. However, the way in which it explains the relation between objective structures and the habitus blurs the active role of the agent in the transformation of its own dispositions. In summary, this article analyzes how the concept of habitus may appear as a fulcrum to explain the continuity of the provisions, but at the same time, the concept is insufficient to duly explain the process of transformation of the different facets of singularity

Multimuons events and primary composition

Nucleon decay detectors at large depths offers now a total area larger than 1000 sq m to registrate muons of energy exceeding 1 TeV. Near complete high energy muon families are detected in those arrays. An extensive 3D Monte-Carlo simulation was conducted in view to understand the spatial distribution of those events and the possible link with elementary act or primary composition. As pion or kaon parents have a very small decay probability at so high energy, multimuon phenomena occurs at high altitude where the atmospheric density is small after the most energetic collisions

Multiple Production, Transport in Atmosphere and Detection of High Energy Cosmic Rays

We describe the general aspects of Monte Carlo Collision Generators suitable for cosmic ray nucleon-Air and nuclei-Air interactions, including accelerator and collider data. The problem of the extrapolation at 3 energy decades above the LHC of the main features of high energy collisions is discussed and under theoretical and phenomenological assumptions, the properties of the longitudinal and lateral development of giant extensive air showers simulated with the CORSIKA program are presented. The determination of the primary energy near $10^{20}$ eV is examined for different observables, total size, densities of charged particles interpolated at 600~m from shower core. The extensive air shower data collected around LHC energy is in better agreement with models of large multiplicities. Beyond this energy, the extrapolation carried assuming the diquark breaking mechanism can change the classic conversion to primary energy and such circumstance can have consequences on the validity of the GZK cut off. In those conditions, we have simulated large and giant air showers taking into account, in addition, new processes, such as diquark breaking, and topological problems involving adequate structure functions for lateral distributions, up to energies exceeding $10^{20}$ eV for P.AUGER and EUSO experiments.Comment: 10 pages, 8 figures (6 in eps, 2 in ps) talk given at XXXI International Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China URL http://ismd31.ccnu.edu.cn

Ultra high energy events in ECHOS series and primary energy spectrum

The compilation of ultra high energy jets suggests at present the existence of a bump in primary energy spectrum (with the standard concept of high energy collisions). The pseudo-rapidity distribution exhibits some typical anomalies, more than the (P sub t) behavior, which are (may be) the fingerprints of quark gluon plasma transition. The next results of Emulsion Chamber on Supersonic (ECHOS) will be in both cases determinant to confirm those tendancies, as well as an important effort of the cosmic ray community to develop in that sense a flying emulsion chamber experiment

Measuring the UHE cosmic-ray composition with tracking detectors in air shower arrays

Measuring the angles of muons and electrons in air showers is proposed as a method for studying the primary cosmic-ray mass composition near the knee of the cosmic-ray energy spectrum at a few $10^{15}$ eV. Conventional tracking detectors at existing air shower arrays could serve this purpose, like the CRT detectors at the HEGRA array. When the average radial muon angles are examined as a function of shower core distance, the experimental resolution can be very well calibrated from the tangential angle distribution. The method is particularly promising for measuring changes in the average mass number of the primary cosmic rays with energy. The method is described and experimental and theoretical constraints are discussed.Comment: 14 pages, 7 figures included. Accepted by Astroparticle Physics. This paper and descriptions of the CRT detectors are also available via http://eu6.mpi-hd.mpg.de/CRT/CRT-eprints.htm