Depth Development of Extensive Air Showers from Muon Time Distributions

We develop a potential algorithm to relate the depth development of ultra high energy extensive air showers and the time delay for individual muons. The time distributions sampled at different positions at ground level by a large air shower array are converted into distributions of production distances using an approximate relation between production distance, transverse distance and time delay. The method is naturally restricted to inclined showers where muons dominate the signal at ground level but could be extended to vertical showers provided that the detectors used can separate the muon signal from electrons and photons. We explore the accuracy and practical uncertainties involved in the proposed method. For practical purposes only the muons that fall outside the central region of the shower can be used, and we establish cuts in transverse distance. The method is tested using simulated showers by comparing the production distance distributions obtained using the method with the actual distances in the simulated showers. It could be applied in the search of neutrinos to increase the acceptance to highly penetrating particles, as well as for unraveling the relative compositions of protons and heavy nuclei. We also illustrate that the obtained depth distributions have minimum width when both the arrival direction and the core position are well reconstructed.Comment: 16 pages, 11 figures. Accepted for publication in Astropart. Phy

Cosmic Rays at the highest energies

After a century of observations, we still do not know the origin of cosmic rays. I will review the current state of cosmic ray observations at the highest energies, and their implications for proposed acceleration models and secondary astroparticle fluxes. Possible sources have narrowed down with the confirmation of a GZK-like spectral feature. The anisotropy observed by the Pierre Auger Observatory may signal the dawn of particle astronomy raising hopes for high energy neutrino observations. However, composition related measurements point to a different interpretation. A clear resolution of this mystery calls for much larger statistics than the reach of current observatories.Comment: 8 pages, 4 figures, in the Proceedings of TAUP 201

Pluto: A Monte Carlo Simulation Tool for Hadronic Physics

Pluto is a Monte-Carlo event generator designed for hadronic interactions from Pion production threshold to intermediate energies of a few GeV per nucleon, as well as for studies of heavy ion reactions. This report gives an overview of the design of the package, the included models and the user interface.Comment: XI International Workshop on Advanced Computing and Analysis Techniques in Physics Research, April 23-27 2007, Amsterdam, the Netherland

Mitogenome and Nuclear-encoded Fungicide-target Genes of Thecaphora frezii - Causal Agent of Peanut Smut

Background: Thecaphora frezii Carranza and Lindquist causes smut disease in peanut (Arachis hypogaea L.) resulting in up to 35% yield losses. Fungicides have shown ineffective in controlling the disease; whereas research on the molecular basis of that fungicide resistance has been hindered because of the lack of genetic information about T. frezii. The goal of this work was to provide molecular information about fungicide-target loci in T. frezii, including its mitochondrial genome (mitogenome) and critical nuclear-encoded genes. Results: Here we report the complete annotated mitogenome of T. frezii, a 123,773 bp molecule containing the standard 14 genes that form part of mitochondrial complexes I, III, IV and V, 22 transfer RNAs, small and large subunits of ribosomal RNA, DNA polymerase, ribonuclease P, GII-reverse transcriptase/maturase, nine hypothetical open-reading frames and homing endonucleases (LAGLIDADG, GIY-YIG, HEG). In addition, we report the full-length cDNA sequence of T. frezii cytochrome b (cob) and cytochrome oxidase 1 (cox1) genes; as well as partial sequences of T. frezii succinate dehydrogenase (sdhb), ergosterol biosynthesis (Erg4), cytochrome P450 (cyp51), and beta tubulin (β-tubulin) genes, which are respective targets of strobilurins, quinone oxidation inhibitors, triazoles and beta-tubulin inhibitor fungicides commonly used in the peanut crop. Translation of cob and sdhb genes in this particular T. frezii isolate suggests potential resistance to strobilurin and carboxamide fungicides. Conclusion: The mitogenome and nuclear-encoded gene sequences presented here provide the molecular tools to research T. frezii fungicide-target loci

On the muon scale of air showers and its application to the AGASA data

Recently, several experiments reported a muon deficit in air shower simulations with respect to the data. This problem can be studied using an estimator that quantifies the relative muon content of the data with respect to those of proton and iron Monte Carlo air shower simulations. We analyze two estimators. The first one, based on the logarithm of the mean of the muon content, is built from experimental considerations. It is ideal for comparing results from different experiments as it is independent of the detector resolution. The second estimator is based on the mean of the logarithm of the muon content, which implies that it depends on shower-to-shower fluctuations. It is linked to the mean-logarithmic mass $⟨ln A⟩$ through the Heitler-Matthews model. We study the properties of the estimators and their biases considering the knowns and unknowns of typical experiments. Furthermore, we study these effects in measurements of the muon density at 1000m from the shower axis obtained by the Akeno Giant Air Shower Array (AGASA). Finally, we report the estimates of the relative muon content of the AGASA data, which support a muon deficit in simulations. These estimates constitute valuable additional information of the muon content of air showers at the highest energies

Sources of UHECRs in view of the TUS and JEM-EUSO experiments

The origin of ultra-high-energy cosmic rays (UHECRs) is one of the most intriguing problems of modern cosmic ray physics. We briefly review the main astrophysical models of their origin and the forthcoming orbital experiments TUS and JEM-EUSO, and discuss how the new data can help one solve the long-standing puzzle.Comment: 4 pages; prepared for ECRS-2012 (http://ecrs2012.sinp.msu.ru/); v2: a reference adde

A novel method for the absolute fluorescence yield measurement by AIRFLY

One of the goals of the AIRFLY (AIR FLuorescence Yield) experiment is to measure the absolute fluorescence yield induced by electrons in air to better than 10% precision. We introduce a new technique for measurement of the absolute fluorescence yield of the 337 nm line that has the advantage of reducing the systematic uncertainty due to the detector calibration. The principle is to compare the measured fluorescence yield to a well known process - the Cerenkov emission. Preliminary measurements taken in the BFT (Beam Test Facility) in Frascati, Italy with 350 MeV electrons are presented. Beam tests in the Argonne Wakefield Accelerator at the Argonne National Laboratory, USA with 14 MeV electrons have also shown that this technique can be applied at lower energies.Comment: presented at the 5th Fluorescence Workshop, El Escorial - Madrid, Spain, 16 - 20 September 200

Hadron-Hadron and cosmic-ray interactions at multi-TeV energies

The workshop on "Hadron-Hadron and Cosmic-Ray Interactions at multi-TeV Energies" held at the ECT centre (Trento) in Nov.-Dec. 2010 gathered together both theorists and experimentalists to discuss issues of the physics of high-energy hadronic interactions of common interest for the particle, nuclear and cosmic-ray communities. QCD results from collider experiments-mostly from the LHC but also from the Tevatron, RHIC and HERA-were discussed and compared to various hadronic Monte Carlo generators, aiming at an improvement of our theoretical understanding of soft, semi-hard and hard parton dynamics. The latest cosmic-ray results from various ground-based observatories were also presented with an emphasis on the phenomenological modeling of the first hadronic interactions of the extended air-showers generated in the Earth atmosphere. These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting

Temperature and Humidity Dependence of Air Fluorescence Yield measured by AIRFLY

The fluorescence detection of ultra high energy cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules over a wide range of atmospheric parameters, corresponding to altitudes typical of the cosmic ray shower development in the atmosphere. We have studied the temperature and humidity dependence of the fluorescence light spectrum excited by MeV electrons in air. Results for the 313.6 nm, 337.1 nm, 353.7 nm and 391.4 nm bands are reported in this paper. We found that the temperature and humidity dependence of the quenching process changes the fluorescence yield by a sizeable amount (up to 20%) and its effect must be included for a precise estimation of the energy of ultra high energy cosmic rays.Comment: presented at the 5th Fluorescence Workshop, El Escorial - Madrid, Spain, 16 - 20 September 2007, to appear in Nuclear Instruments and Methods