Influence of shower fluctuations and primary composition on studies of the shower longitudinal development

We study the influence of shower fluctuations, and the possible presence of different nuclear species in the primary cosmic ray spectrum, on the experimental determination of both shower energy and the proton air inelastic cross section from studies of the longitudinal development of atmospheric showers in fluorescence experiments. We investigate the potential of track length integral and shower size at maximum as estimators of shower energy. We find that at very high energy (~10^19-10^20 eV) the error of the total energy assignment is dominated by the dependence on the hadronic interaction model, and is of the order of 5%. At lower energy (~10^17-10^18 eV), the uncertainty of the energy determination due to the limited knowledge of the primary cosmic ray composition is more important. The distribution of depth of shower maximum is discussed as a measure of the proton-air cross section. Uncertainties in a possible experimental measurement of this cross section introduced by intrinsic shower fluctuations, the model of hadronic interactions, and the unknown mixture of primary nuclei in the cosmic radiation are numerically evaluated.Comment: 12 pages, 11 figures, 4 table

Design and Characterization of Electrospun Polyamide Nanofiber Media for Air Filtration Applications

Electrospun polyamide 6 (PA 6) and polyamide 6/6 (PA 6/6) nanofibers were produced in order to investigate their experimental characteristics with the goal of obtaining filtration relevant fiber media. The experimental design model of each PA nanofibers contained the following variables: polymer concentration, ratio of solvents, nanofiber media collection time, tip-to-collector distance, and the deposition voltage. The average diameter of the fibers, their morphology, basis weight, thickness, and resulting media solidity were investigated. Effects of each variable on the essential characteristics of PA 6/6 and PA 6 nanofiber media were studied. The comparative analysis of the obtained PA 6/6 and PA 6 nanofiber characteristics revealed that PA 6/6 had higher potential to be used in filtration applications. Based on the experimental results, the graphical representation—response surfaces—for obtaining nanofiber media with the desirable fiber diameter and basis weight characteristics were derived. Based on the modelling results the nanofiber filter media (mats) were fabricated. Filtration results revealed that nanofiber filter media electrospun from PA6/6 8% (w/vol) solutions with the smallest fiber diameters (62–66 nm) had the highest filtration efficiency (PA6/6_30 = 84.9–90.9%) and the highest quality factor (PA6/6_10 = 0.0486–0.0749 Pa−1)

Noncentrosymmetric Packings Influenced by Electronic Properties of Products of Click Reactions

Though 1,4-disubstituted 1,2,3-triazole rings have been utilized as electronic bridges in the solution phase, the use of a triazole ring to serve as an electronic bridge of small molecules in the crystalline state has been underdeveloped. Here two compounds with a central 1,4-disubstituted 1,2,3-triazole ring are synthesized to investigate the electronic bridging between terminal stilbazole and pyridine groups in the crystalline phase. The electronic properties of the molecules are characterized through solution phase UV–vis spectroscopy, single crystal X-ray diffractions, and density-of-state and gas-phase DFT calculations. We show that the electronic bridging behavior of a 1,4-disubstituted 1,2,3-triazole ring derived from a click reaction is maintained in the solid state by rare head-to-head (hh) packing in noncentrosymmetric crystal environments

On the measurement of the proton-air cross section using longitudinal shower profiles

In this paper, we will discuss the prospects of deducing the proton-air cross section from fluorescence telescope measurements of extensive air showers. As it is not possible to observe the point of first interaction $X_{\rm 1}$ directly, other observables closely linked to $X_{\rm 1}$ must be inferred from the longitudinal profiles. This introduces a dependence on the models used to describe the shower development. The most straightforward candidate for a good correlation to $X_{\rm 1}$ is the depth of shower maximum $X_{\rm max}$. We will discuss the sensitivity of an $X_{\rm max}$-based analysis on $\sigma_{\rm p-air}$ and quantify the systematic uncertainties arising from the model dependence, parameters of the reconstruction method itself and a possible non-proton contamination of the selected shower sample.Comment: 4 pages, Proceedings for ISVHECRI Weihei 200

Limits on deeply penetrating particles in the 10(17) eV cosmic ray flux

Deeply penetrating particles in the 10 to the 17th power eV cosmic ray flux were investigated. No such events were found in 8.2 x 10 to the 6th power sec of running time. Limits were set on the following: quark-matter in the primary cosmic ray flux; long-lived, weakly interacting particles produced in p-air collisions; the astrophysical neutrino flux. In particular, the neutrino flux limit at 10 to the 17th power eV implies that z, the red shift of maximum activity is 10 in the model of Hill and Schramm

Possibility of Using a Satellite-Based Detector for Recording Cherenkov Light from Ultrahigh-Energy Extensive Air Showers Penetrating into the Ocean Water

We have estimated the reflected component of Cherenkov radiation, which arises in developing of an extensive air shower with primary energy of 10^20 eV over the ocean surface. It has been shown that, under conditions of the TUS experiment, a flash of the reflected Cherenkov photons at the end of the fluorescence track can be identified in showers with zenith angles up to 20 degrees.Comment: 5 pages, 3 figures. This preprint corrects errors which appeared in the English version of the article published in Bull. Rus. Acad. Sci. Phys., 2011, Vol. 75, No. 3, p. 381. The original russian text was published in Izv. RAN. Ser. Fiz., 2011, Vol. 75, No. 3, p. 41

Electromagnetic form factors in the J/\psi mass region: The case in favor of additional resonances

Using the results of our recent analysis of e^+e^- annihilation, we plot the curves for the diagonal and transition form factors of light hadrons in the time-like region up to the production threshold of an open charm quantum number. The comparison with existing data on the decays of J/\psi into such hadrons shows that some new resonance structures may be present in the mass range between 2 GeVand the J/\psi mass. Searching them may help in a better understanding of the mass spectrum in both the simple and a more sophisticated quark models, and in revealing the details of the three-gluon mechanism of the OZI rule breaking in K\bar K channel.Comment: Formulas are added, typo is corrected, the text is rearranged. Replaced to match the version accepted in Phys Rev

The structure of EAS at E 0.1 EeV

The ratio of extensive air showers (EAS) total shower energy in the electromagnetic channel (E em) to the size of the shower at maximum development (N max) from a direct measurement of shower longitudinal development using the air fluorescence technique was calculated. The values are not inconsistent with values based upon track length integrals of the Gaisser-Hillas formula for shower development or the known relation between shower energy and size at maximum for pure electromagnetic cascades. Using Linsley's estimates for undetected shower energy based on an analysis of a wide variety of cosmic ray data, the following relation for total shower energy E vs N max is obtained. The Gaisser Hillas implied undetected shower energy fractions

Consequences of the Factorization Hypothesis in pbar p, pp, gamma p and gamma gamma Collisions

Using an eikonal analysis, we examine the validity of the factorization theorem for nucleon-nucleon, gamma p and gamma gamma collisions. As an example, using the additive quark model and meson vector dominance, we directly show that for all energies and values of the eikonal, that the factorization theorem sigma_{nn}/sigma_{gamma p} = sigma_{gamma p}/sigma_{gamma gamma} holds. We can also compute the survival probability of large rapidity gaps in high energy pbar p and pp collisions. We show that the survival probabilities are identical (at the same energy) for gamma p and gamma gamma collisions, as well as for nucleon-nucleon collisions. We further show that neither the factorization theorem nor the reaction-independence of the survival probabilities depends on the assumption of an additive quark model, but, more generally, depends on the opacity of the eikonal being independent of whether the reaction is n-n, gamma p or gamma gamma.Comment: 8 pages, Revtex, no figures. Expanded discussion, minor correction