arXiv subjects

Stephen Reucroft

Publications and source records attributed to Stephen Reucroft.

12 recordsLinked to original sources

arXiv2005

Gluino Air Showers as a Signal of Split Supersymmetry

It has been proposed recently that, within the framework of split Supersymmetry, long lived gluinos generated in astrophysical sources could be detected using the signatures of the air showers they produce, thus providing a lower bound for their lifetime and for the scale of SUSY breaking. We present the longitudinal profile and lateral spread of $G$-hadron induced extensive air showers and consider the possibility of measuring them with a detector with the characteristics of the Pierre Auger Observatory.

hep-ph↗

arXiv2004

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.

hep-ph↗

arXiv2003

Full-Sky Search for Ultra High Energy Cosmic Ray Anisotropies

Using data from the SUGAR and the AGASA experiments taken during a 10 yr period with nearly uniform exposure to the entire sky, we search for large-scale anisotropy patterns in the arrival directions of cosmic rays with energies > 10^{19.6} eV. We determine the angular power spectrum from an expansion in spherical harmonics for modes out to \ell=5. Based on available statistics, we find no significant deviation from isotropy. We compare the rather modest results which can be extracted from existing data samples with the results that should be forthcoming as new full-sky observatories begin operation.

astro-ph↗

arXiv2003

On the cross correlation between the arrival direction of ultra-high energy cosmic rays, BL Lacertae, and EGRET detections: A new way to identify EGRET sources?

With the aim of testing recent claims for a particularly strong correlation between ultra-high energy cosmic rays (UHECRs), observed with the AGASA and the Yakutsk experiments, and a sample of BL Lacertae (BL Lacs), we here conduct a blind statistical assessment. We search for associations between the same set of BL Lac objects and the arrival directions of 33 relevant UHECRs observed with the Haverah Park and the Volcano Ranch experiments. Within the accuracy of angle determination, there are no positional coincidences. The probability that this null result arises as a statistical fluctuation from the strongly correlated case is less than 5%. This implies that the possible correlation between the arrival directions of UHECRs and BL Lacs is not statistically sustained. We discuss the impact of our findings on the propose additional connection among UHECRs, BL Lacs, and EGRET gamma-ray blazars. Recently, such an association was used as classification technique for EGRET sources. Here we show that its main underlying hypothesis, i.e., the EGRET angular uncertainty is twice that quoted in the Third EGRET Catalog, underestimates the goodness of existing gamma-ray data.

astro-ph↗

arXiv2003

Numerical Likelihood Analysis of Cosmic Ray Anisotropies

A numerical likelihood approach to the determination of cosmic ray anisotropies is presented which offers many advantages over other approaches. It allows a wide range of statistically meaningful hypotheses to be compared even when full sky coverage is unavailable, can be readily extended in order to include measurement errors, and makes maximum unbiased use of all available information.

astro-ph↗

arXiv2003

SCROD: School Cosmic Ray Outreach Detector

We report progress on applying technologies developed for LHC-era experiments to cosmic ray detection, using scintillating tiles with embedded wavelength-shifting fibers and avalanche photodiode readouts as parts of a robust, inexpensive cosmic air shower detector. We are planning to deploy such detectors in high schools as part of an outreach effort able to search for long-distance correlations between airshowers.

astro-ph↗

arXiv2002

Ultrahigh Energy Cosmic Rays: The state of the art before the Auger Observatory

In this review we discuss the important progress made in recent years towards understanding the experimental data on cosmic rays with energies $\agt 10^{19}$ eV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition, and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the conjectured nearby cosmic ray sources. We then turn to theoretical notions of physics beyond the Standard Model where we consider both exotic primaries and exotic physical laws. Particular attention is given to the role that TeV-scale gravity could play in addressing the origin of the highest energy cosmic rays. In the final part of the review we discuss the potential of future cosmic ray experiments for the discovery of tiny black holes that should be produced in the Earth's atmosphere if TeV-scale gravity is realized in Nature.

hep-ph↗

arXiv2001

The Mysterious Ultrahigh Energy Cosmic Ray Clustering

We examine the correlation between compact radio quasars (redshifts in the range $z = 0.3 - 2.2$) and the arrival direction of ultrahigh energy cosmic rays forming clusters. Our Monte Carlo simulation reveals a statistically significant correlation on the AGASA sample: the chance probability of this effect being less than 1%. The implications of this result on the origin of ultrahigh energy cosmic rays are discussed.

astro-ph↗

arXiv2001

Extragalactic Sources for Ultra High Energy Cosmic Ray Nuclei

In this article we examine the hypothesis that the highest energy cosmic rays are complex nuclei from extragalactic sources. Under reasonable physical assumptions, we show that the nearby metally rich starburst galaxies (M82 and NGC 253) can produce all the events observed above the ankle. This requires diffusion of particles below $10^{20}$ eV in extragalactic magnetic fields $B \approx 15$ nG. Above $10^{19}$ eV, the model predicts the presence of significant fluxes of medium mass and heavy nuclei with small rate of change of composition. Notwithstanding, the most salient feature of the starburst-hypothesis is a slight anisotropy induced by iron debris just before the spectrum-cutoff.

hep-ph↗

arXiv2001

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 ($σ_{νN}$) beyond Standard Model predictions. At ultra-high 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.

hep-ph↗

arXiv2000

Echoes of the fifth dimension?

In this article we examine the question of whether the highest energy cosmic ray primaries could be ultra relativistic magnetic monopoles. The analysis is performed within the framework of large compact dimensions and TeV scale quantum gravity. Our study indicates that while this hypothesis must be regarded as highly speculative it cannot be ruled out with present data.

hep-ph↗

arXiv2000

Scalable Parallel Implementation of Geant4 Using Commodity Hardware and Task Oriented Parallel C

We describe a scalable parallelization of Geant4 using commodity hardware in a collaborative effort between the College of Computer Science and the Department of Physics at Northeastern University. The system consists of a Beowulf cluster of 32 Pentium II processors with 128 MBytes of memory each, connected via ATM and fast Ethernet. The bulk of the parallelization is done using TOP-C (Task Oriented Parallel C), software widely used in the computational algebra community. TOP-C provides a flexible and powerful framework for parallel algorithm development, is easy to learn, and is available at no cost. Its task oriented nature allows one to parallelize legacy code while hiding the details of interprocess communications. Applications include fast interactive simulation of computationally intensive processes such as electromagnetic showers. General results motivate wider applications of TOP-C to other simulation problems as well as to pattern recognition in high energy physics.

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