Air Shower Data Research Articles

Can We Understand High Energy Cosmic-Ray Spectra on the Basis of the Scaling Hypothesis?

Using the essential point of Feynman's hadronic scaling hypothesis, we have made a calculation of atmospheric cosmic-ray spectra, i.e., spectra of muons, hadrons and electro­ magnetic component. The results are compared with emulsion chamber data on the three components. In doing so, various factors related to the primary cosmic-ray spectrum are carefully examined. It is shown that the scaling feature of particle production in the entire energy region (up to several times lO"eV) is compatible with the data only when one assumes i) very large inelastic cross-sections (~380mb for p-air collisions) and ii) the steepening of the (proton equivalent) primary cosmic-rays above several times IO"eV, of which the intensity is much less than some air shower data. Another feasible way of understanding the phenomena is discussed by hypothesizing a break of the scaling feature in the fragmentation region at high energies (;(:10 14 e V).

Do extensive air shower data provide reliable information on the proton-proton total cross section?

The zenith angle dependence of frequencies of extensive air showers is discussed from the point of view of nucleon-nucleon total cross sections. It is shown that this kind of data cannot (without additional assumptions) distinguish between asymptotically constant cross sections and those increasing as In s or even as (In s)2.

Cosmic rays and particle physics at extremely high energies

Cosmic ray extensive air shower observations can give clues about the properties of high-energy particle interactions above 1015eV, in addition to giving information about the primary cosmic ray spectrum at these energies. A brief review of recent high energy accelerator data and its theoretical interpretation is given to explain the necessity for obtaining information from cosmic rays about hadronic interactions beyond machine energies. In particular, it is shown that recent measurements of the energy dependence of total cross-sections and of production cross-sections suggest some sort of threshold behavior in the 1000 GeV region. Studies at higher energies are required to understand the nature of this behavior. The use of air shower data for this purpose is illustrated by comparing shower size us depth measurements with the expectations of various models of strong interactions.

Extensive air showers and Feynman scaling above 1000 GeV

We describe a method for using extensive air shower data to determine whether a Feynman scaling limit exists in the central region for inclusive cross sections. Preliminary analysis suggests that the shower muon to electron ratio is more consistent with a power law increase of pion multiplicity with energy than with the logarithmic multiplicity increase characteristic of a scaling limit, but an analysis of the intra-nuclear cascade is required to reach a firm conclusion.

On observed and predicted multiplicities in very-high-energy interactions

Recent hydrogen bubble chamber and hydrogen target multiplicity data are compared with the bulk of existing data over the entire experimental energy range, from 10 to 108 GeV. The data are compared with multiplicity predictions, derived from different interaction models. Included in the analysis are also results obtained from recent large-scale air shower simulations, in conjunction with experimental air shower data. Multiplicity tendencies of very-high-energy nucleon-nucleus interactions, as observed in emulsion and derived from air shower simulations, are discussed in view of the recent HBC and hydrogen target data.

Origin and Composition of Ultrahigh Energy Cosmic Rays

DISCUSSIONS of the problem of the origin of ultrahigh energy cosmic rays have centred on three characteristics of their energy spectrum: (1) an apparent steepening of the power-law integral spectrum, E−γ from γ≃ 1.7 to γ≃ 2.2 at an energy of ∼ 1015 eV ; (2) an apparent flattening of the spectrum at an energy above 3×1018 eV where γ≃1.6 and (3) the apparent absence of a cutoff in the energy spectrum of air-shower events at energies above 1019 eV. Recently, the validity of the second characteristic has been questioned and a new analysis of both the Haverah Park and Volcano Ranch air-shower data has indicated that γ≃2.2 for energies above 1017 eV (refs. 1 and 2). I suggest that, if this is the case, the absence of a flattening above 3 × 1018 eV may have implications for the debate about the origin of ultrahigh energy cosmic rays (UECR).

Limits on Magnetic Monopole Fluxes in the Primary Cosmic Radiation from Inverse Compton Scattering and Muon-Poor Extensive Air Showers

Flux limits for monopoles in the primary cosmic radiation have been derived on the basis of muon-poor air-shower data and the analog of inverse Compton scattering of monopoles from universal microwave background photons. Calculations on both galactic and universal scales were performed. The resulting limits are generally smaller than existing experimental limits and are applicable to strongly interacting monopoles.