A Review on the Potential Applications for Cadmium Selenide and Graphene Materials

The unique physical and chemical properties for nanomaterials make them suitable to be used in different applications such as optoelectronic devices, sensors, and biomedical applications. Physical and chemical methods are used to prepare material in nanoscale region. Physical methods depend on the technique used, temperature, and substrate. Cadmium selenide has high sensitive to technique used. Its absorbance and photoluminescence changed with increased size of particles. The surfaces of CdSe can adsorbent different atoms and molecules to saturate dangling bond. Therefore, CdSe nanoparticales are used in chemical and biological sensors. In this review some of recent applications and properties of CdSe are analyzed. Graphene considers one of the important material in the present time, because of unique properties such as high conductivity, high luminance, more hardness materials than diamonds. It is have wide applications in the physical and chemical sensor, also suitable material in the photonic device. In the present review paper we are present the application of graphene materials in the gas sensor and solar cell application.&nbsp

Degradation of Indigo Dye Using Quantum Mechanical Calculations

The semiempirical (PM3) and DFT quantum mechanical methods were used to investigate the theoretical degradation of Indigo dye. The chemical reactivity of the Indigo dye was evaluated by comparing the potential energy stability of the mean bonds. Seven transition states were suggested and studied to estimate the actually starting step of the degradation reaction. The bond length and bond angle calculations indicate that the best active site in the Indigo dye molecule is at C10=C11.  The most possible transition states are examined for all suggested paths of Indigo dye degradation predicated on zero-point energy and imaginary frequency. The first starting step of the reaction mechanism is proposed. The change in enthalpy, Gibbs free energy and change in entropy of the overall reaction are equal to -548268.223 kcal/mol, 30831.951 kcal/mol and 48.552 cal/mol.deg, respectively. The activation energy is 46176.405 kcal/mol. The reaction rate is equal to

Maximum Likelihood Analysis of Clusters of Ultra-High Energy Cosmic Rays

We present a numerical code designed to conduct a likelihood analysis for clusters of nucleons above 10**19 eV originating from discrete astrophysical sources such as powerful radio galaxies, gamma-ray bursts or topological defects. The code simulates the propagation of nucleons in a large-scale magnetic field and constructs the likelihood of a given observed event cluster as a function of the average time delay due to deflection in the magnetic field, the source activity time scale, the total fluence of the source, and the power law index of the particle injection spectrum. Other parameters such as the coherence length and the power spectrum of the magnetic field are also considered. We apply it to the three pairs of events above 4X10**19 eV recently reported by the Akeno Giant Air Shower Array (AGASA) experiment, assuming that these pairs were caused by nucleon primaries which originated from a common source. Although current data are too sparse to fully constrain each of the parameters considered, and/or to discriminate models of the origin of ultra-high energy cosmic rays, several tendencies are indicated. If the clustering suggested by AGASA is real, next generation experiments with their increased exposure should detect more than 10 particles per source over a few years and our method will put strong constraints on both the large-scale magnetic field parameters and the nature of these sources.Comment: 11 latex pages, 8 postscript figures included, uses revtex.sty in two-column format and epsf.sty. Submitted to Physical Review

Extension of the Cosmic-Ray Energy Spectrum Beyond the Predicted Greisen-Zatsepin-Kuz'min Cutoff

The cosmic-ray energy spectrum above 10^{18.5} eV is reported using the updated data set of the Akeno Giant Air Shower Array (AGASA) from February 1990 to October 1997. The energy spectrum extends beyond 10^{20} eV and the energy gap between the highest energy event and the others is being filled up with recently observed events. The spectral shape suggests the absence of the 2.7 K cutoff in the energy spectrum or a possible presence of a new component beyond the 2.7 K cutoff.Comment: to be published in PRL, 3 figures, REVTEX forma

Radio-controlled xenon flashers for atmospheric monitoring at the HiRes cosmic ray observatory

Stable, robust ultraviolet light sources for atmospheric monitoring and calibration pose a challenge for experiments that measure air fluorescence from cosmic ray air showers. One type of light source in use at the High Resolution Fly's Eye (HiRes) cosmic ray observatory features a xenon flashbulb at the focal point of a spherical mirror to produce a 1 μs pulse of collimated light that includes a strong UV component. A computer-controlled touch tone radio system provides remote operation of bulb triggering and window heating. These devices, dubbed 'flashers', feature stand-alone operation, ± 5% shot-to-shot stability, weather proof construction and are well suited for long-term field use. This paper describes the flashers, the radio control system, and a 12-unit array in operation at the HiRes cosmic ray observatory.http://www.elsevier.com/wps/find/journaldescription.cws_home/505701/description#descriptio

The prototype high-resolution Fly's Eye cosmic ray detector

Copyright © 2000 Elsevier Science B.V. All rights reserved.The High-Resolution Fly's Eye (HiRes) is an observatory for the highest energy cosmic rays. It detects the nitrogen fluorescence light induced by the passage of giant cosmic ray extensive air showers through the atmosphere. A two-site prototype of the observatory was operated from September 1994 to November 1996. In this paper we describe the components of that detector, and the procedures used to calibrate the detector and characterise the atmosphere. Data collected by the HiRes prototype are being used for physics studies, including an analysis of the cosmic ray mass composition in the energy range from 1017 to 1018 eV.T. Abu-Zayyad, M. Al-Seady, K. Belov, D. J. Bird, J. Boyer, G. Chen, R. W. Clay, H. Y. Dai, B. R. Dawson, Y. Ho, M. A. Huang, C. C. H. Jui, M. J. Kidd, D. B. Kieda, B. C. Knapp, W. Lee, E. C. Loh, E. J. Mannel, J. N. Matthews, T. A. O'Halloran, A. Salman, K. M. Simpson, J. D. Smith, P. Sokolsky, P. Sommers, S. B. Thomas, L. R. Wiencke, C. R. Wilkinson and N. R. Wildhttp://www.elsevier.com/wps/find/journaldescription.cws_home/505701/description#descriptio

Geometrical reconstruction with the High Resolution Fly's Eye prototype cosmic ray detector

Copyright © 1999 Published by Elsevier Science B.V.The High Resolution Fly's Eye EHE cosmic ray detector (HiRes) was operated for over two years (prior to November 1996) in a two-site prototype configuration. This paper describes the development and testing of an event reconstruction method for extensive air showers (EAS) viewed in coincidence by both sites (stereo viewing). The reconstruction accuracy was directly measured through the use of a UV laser mounted on a telescope that generated airshower-like events with known geometries. For events observed with stereo opening angles greater than about 10° (most events) the median error in the reconstructed laser direction was 0.4° with 95% of events being reconstructed with errors of less than 0.9° (which degrade to 0.8° and 1.8°, respectively, for smaller opening angles). A limited investigation of the likely performance of the HiRes Stage 1.0 detector was undertaken. Reconstruction accuracy is likely to be only slightly degraded compared with the prototype results.C.R. Wilkinson, T. Abu-Zayyad, M. Al-Seady, K. Belov, D.J. Bird, J. Boyer, G. Chen, R.W. Clay, H.Y. Dai, B.R. Dawson, Y. Ho, M.A. Huang, C.C.H. Jui, M.J. Kidd, D.B. Kieda, B.C. Knapp, W. Lee, E.C. Loh, E.J. Mannel, J.N. Matthews, T.A. O’Halloran, A. Salman, K.M. Simpson, J.D. Smith, P. Sokolsky, P. Sommers, S.B. Thomas, L.R. Wiencke, N.R. Wil

Indications of Proton-Dominated Cosmic-Ray Composition above 1.6 EeV

We report studies of ultra-high energy cosmic ray composition via analysis of depth of airshower maximum (Xmax), for airshower events collected by the High Resolution Fly's Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d/d(log(E)) of 47.9 +- 6.0 (stat.) +- 3.2 (syst.)g/cm^2/decade for energies between 1.6 EeV and 63 EeV, and are consistent with a predominantly protonic composition of cosmic rays when interpreted via the QGSJET01 and QGSJET-II high-energy hadronic interaction models. These measurements constrain models in which the galactic-to-extragalactic transition is the cause of the energy spectrum "ankle' at 4 EeV.Comment: 11 pages, 4 figures, accepted for publication in Physical Review Letter