T. P. McCauley

High energy physics in the atmosphere: Phenomenology of cosmic ray air showers

The properties of cosmic rays with energies above 10 6 GeV have to be deduced from the spacetime structure and particle content of the air showers which they initiate. In this review we summarize the phenomenology of these giant air showers. We describe the hadronic interaction models used to extrapolate results from collider data to ultra high energies, and discuss the prospects for insights into forward physics at the LHC. We also describe the main electromagnetic processes that govern the longitudinal shower evolution, as well as the lateral spread of particles. Armed with these two principal shower ingredients and motivation from the underlying physics, we provide an overview of some of the different methods proposed to distinguish primary species. The properties of neutrino interactions and the potential of forthcoming experiments to isolate deeply penetrating showers from baryonic cascades are also discussed. We finally venture into a terra incognita endowed with TeV-scale gravity and explore anomalous neutrino-induced showers.

Extensive air showers with TeV scale quantum gravity

One of the possible consequences of the existence of extra degrees of freedom beyond the electroweak scale is the increase of neutrino-nucleon cross sections ({sigma}{sub {nu}N}) beyond standard model predictions. At ultrahigh energies this may allow the existence of neutrino-initiated extensive air showers. In this paper, we examine the most relevant observables of such showers. Our analysis indicates that the future Pierre Auger Observatory could be potentially powerful in probing models with large compact dimensions.

The mass composition of cosmic rays near 1018 eV as deduced from measurements made at Volcano Ranch

Linsley used the Volcano Ranch array to collect data on the lateral distribution of showers produced by cosmic rays at energies above 10^17 eV. Very precise measurements of the steepness of the lateral distribution function were made on 366 events. The current availability of sophisticated hadronic interaction models has prompted an interpretation of the measurements. In this analysis we use the AIRES Monte Carlo code to generate showers, together with GEANT4 to simulate the detector response to ground particles. The results show that, with the assumption of a bi-modal proton and iron mix, iron is the dominant component of cosmic rays between 5x10^17 and 10^19 eV, assuming that hadronic interactions are well-described by QGSJET at this energy range.

On the nature of cosmic rays above the Greisen–Zatsepin–Kuz'min cut off

Abstract A re-examination of the atmospheric cascade profile of the highest energy cosmic ray is presented. The study includes air-shower simulations considering different cross sections, particle multiplicity and variation of the hadronic-event-generator to model interactions above 200 GeV. The analysis provides evidence that a medium mass nucleus primary reproduces the shower profile quite well. This result does not support the idea, increasingly popular at present, that the highest energy particles are protons, derived from the decay of supermassive relic particles. On the other hand, we show that debris of relativistic super-heavy nuclei, which can survive a 100 Mpc journey through the primeval radiation are likely to generate such a kind of cascade.

Using TOP-C for commodity parallel computing in cosmic ray physics simulations

Abstract top-c (Task Oriented Parallel C) is a freely available package for parallel computing. It is designed to be easy to learn and to have good tolerance for the high latencies that are common in commodity networks of computers. It has been successfully used in a wide range of examples, providing linear speedup with the number of computers. A brief overview of top-c is provided, along with recent experience with cosmic ray physics simulations.

Cosmic-ray Monte Carlo predictions for forward particle production in p-p, p-Pb, and Pb-Pb collisions at the LHC

AbstractWe present and compare the predictions of various cosmic-ray Monte Carlo models for the energy (dE/dη) and particle (dN/dη) flows in p-p, p-Pb and Pb-Pb collisions at

Possible explanation for the tail of the cosmic ray spectrum

nsqrt {s_{NN} } n

A pot of gold at the end of the cosmic “raynbow”?

= 14, 8.8, and 5.5 TeV respectively, in the range covered by forward LHC detectors like CASTOR or TOTEM (5.2 < |η|<6.6) and ZDC or LHCf (|η| ≥ 8.1 for neutrals).