Search

We have searched for correlations between the pointing directions of ultrahigh energy cosmic rays observed by the High Resolution Fly's Eye experiment and Active Galactic Nuclei (AGN) visible from its northern hemisphere location. No correlations, other than random correlations, have been found. We report our results using search parameters prescribed by the Pierre Auger collaboration. Using these parameters, the Auger collaboration concludes that a positive correlation exists for sources visible to their southern hemisphere location. We also describe results using two methods for determining the chance probability of correlations: one in which a hypothesis is formed from scanning one half of the data and tested on the second half, and another which involves a scan over the entire data set. The most significant correlation found occurred with a chance probability of 24%., 13 pages, 1 table, 5 figures

Air fluorescence detectors traditionally determine the dominant chemical composit ion of the ultrahigh energy cosmic ray flux by comparing the averaged slant depth of the shower maximum, $X_{max}$, as a function of energy to the slant depths expect ed for various hypothesized primaries. In this paper, we present a method to make a direct measurement of the expected mean number of protons and iron by comparing the shap es of the expected $X_{max}$ distributions to the distribution for data. The advantages of this method includes the use of information of the full distribution and its ability to calculate a flux for various cosmic ray compositi ons. The same method can be expanded to marginalize uncertainties due to choice of spectra, hadronic models and atmospheric parameters. We demonstrate the technique with independent simulated data samples from a parent sample of protons and iron. We accurately predict the number of protons and iron in the parent sample and show that the uncertainties are meaningful., 11 figures, 22 pages, accepted by Astroparticle Physics

Air fluorescence measurements of cosmic ray energy must be corrected for attenuation of the atmosphere. In this paper we show that the air-showers themselves can yield a measurement of the aerosol attenuation in terms of optical depth, time-averaged over extended periods. Although the technique lacks statistical power to make the critical hourly measurements that only specialized active instruments can achieve, we note the technique does not depend on absolute calibration of the detector hardware, and requires no additional equipment beyond the fluorescence detectors that observe the air showers. This paper describes the technique, and presents results based on analysis of 1258 air-showers observed in stereo by the High Resolution Fly's Eye over a four year span., Comment: 7 pages, 3 figures, accepted for publication by Astroparticle Physics Journal

Data taken in stereo mode by the High Resolution Fly's Eye (HiRes) air fluorescence experiment are analyzed to search for correlations between the arrival directions of ultra--high-energy cosmic rays with the positions of BL Lacertae objects. Several previous claims of significant correlations between BL Lacs and cosmic rays observed by other experiments are tested. These claims are not supported by the HiRes data. However, we verify a recent analysis of correlations between HiRes events and a subset of confirmed BL Lacs from the 10th Veron Catalog, and we study this correlation in detail. Due to the a posteriori nature of the search, the significance level cannot be reliably estimated and the correlation must be tested independently before any claim can be made. We identify the precise hypotheses that will be tested with statistically independent data., Comment: 5 pages, 1 figure, submitted to ApJ

We present the results of a search for cosmic ray point sources at energies above 40 EeV in the combined data sets recorded by the AGASA and HiRes stereo experiments. The analysis is based on a maximum likelihood ratio test using the probability density function for each event rather than requiring an a priori choice of a fixed angular bin size. No statistically significant clustering of events consistent with a point source is found.

The composition of Ultra High Energy Cosmic Rays (UHECR) is measured with the High Resolution Fly's Eye cosmic ray observatory (HiRes) data using the Xmax technique. Data were collected in stereo between 1999 November and 2001 September. The data are reconstructed with well-determined geometry. Measurements of the atmospheric transmission are incorporated in the reconstruction. The detector resolution is found to be 30 g cm^-2 in Xmax and 13% in Energy. The Xmax elongation rate between 10^18.0 eV and 10^19.4 eV is measured to be 54.5 +/- 6.5 (stat) +/- 4.5 (sys) g cm^-2 per decade. This is compared to predictions using the QGSJet01 and SIBYLL 2.1 hadronic interaction models for both protons and iron nuclei. CORSIKA-generated Extensive Air Showers (EAS) are incorporated directly into a detailed detector Monte Carlo program. The elongation rate and the Xmax distribution widths are consistent with a constant or slowly changing and predominantly light composition. A simple model containing only protons and iron nuclei is compared to QGSJet and SIBYLL. The best agreement between the model and the data is at 80% protons for QGSJet and 60% protons for SIBYLL., Comment: 52 pages, 27 figures. Revised Fig. 10 caption, improved Fig. 23, resubmitted to ApJ. (Previously revised to address referee's comments.) (Originally 37 pages, 13 figures. Submitted to ApJ)

The High Resolution Fly's Eye (HiRes) experiment is an air fluorescence detector which, operating in stereo mode, has a typical angular resolution of 06 and is sensitive to cosmic rays with energies above 1018 eV. The HiRes cosmic-ray detector is thus an excellent instrument for the study of the arrival directions of ultra-high-energy cosmic rays. We present the results of a search for anisotropies in the distribution of arrival directions on small scales ( 1019 eV). The search is based on data recorded between 1999 December and 2004 January, with a total of 271 events above 1019 eV. No small-scale anisotropy is found, and the strongest clustering found in the HiRes stereo data is consistent at the 52% level with the null hypothesis of isotropically distributed arrival directions.

The high resolution Fly’s Eye (HiRes) detector in Dugway, Utah, is an air fluorescence detector designed for the measurement of the energy and arrival direction of cosmic ray particles with energy E >10 18 eV. HiRes monitors the night sky for fluorescence light from air shower cascades induced by cosmic ray primaries. The light is collected by mirrors and projected onto arrays of photomultiplier tubes that provide an image of the air shower. HiRes is an astronomical instrument, and the accuracy of the mirror pointing and understanding of the optical properties of the mirror–camera units is crucial. We present a method to cross-check and monitor the mirror pointing by using star light. A star crossing the field of view of a photomultiplier tube causes a temporary increase in the total light detected by the tube. Using UV bright stars, we analyze the pointing accuracy of the HiRes 2 detector, and evaluate the shape of a point-like object as a function of distance to the mirror axis.

We study the spectrum and average mass composition of cosmic rays with primary energies between 10^{17} eV and 10^{18} eV using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum as a function of energy. A complete Monte Carlo simulation of the detector response and comparisons with shower simulations leads to the conclusion that the cosmic ray intensity is changing f rom a heavier to a lighter composition in this energy range. The spectrum is consistent with earlier Fly's Eye measurements and supports the previously found steepening near 4 \times 10^{17} eV .

This article describes the fiber-optic-based calibration system installed at the High Resolution Fly's Eye (HiRes) astro-particle physics observatory. The HiRes detectors measure ultra violet scintillation light from distant extensive air showers. This automated calibration system delivers light from a frequency tripled 355 nm YAG laser to the 10,752 photo-multiplier tubes of the 42 HiRes-II detectors.

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 10 18 eV .

The average mass composition of cosmic rays with primary energies between ${10}^{17}$ and ${10}^{18}\mathrm{eV}$ has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases.

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.

Stable, robust ultraviolet light sources for atmospheric monitoring and calibration pose a challenge for experiments that measure air #uorescence 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 #ashbulb at the focal point of a spherical mirror to produce a 1 ls 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 ‘#ashersa, feature stand-alone operation, $5% shot-to-shot stability, weather proof construction and are well suited for long-term"eld use. This paper describes the #ashers, the radio control system, and a 12-unit array in operation at the HiRes cosmic ray observatory ( 1999 Elsevier Science B.V. All rights reserved.

Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultrahigh energy electron-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current electron-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular dataset has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for electron-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going electron-neutrino-induced cascades and present an upper limit on the flux of electron-neutrinos., Comment: 13 pages, 3 figures. submitted to Astrophysical Journal

In this paper ultra-high energy cosmic rays UHECRs data observed by the HiRes fluorescence detector in stereo mode is analyzed to search for events in the sky with an arrival direction lying on a great circle. Such structure is known as the arc structure. The arc structure is expected when the charged cosmic rays pass through the galactic magnetic field. The arcs searched for could represent a broad or a small scale anisotropy depending on the proposed source model for the UHECRs. The arcs in this paper are looked for using Hough transform were Hough transform is a technique used to looking for patterns in images. No statistically significant arcs were found in this study.

6-Hydroxynicotinic acid intermediate: methyl coumalate product: 6-hydroxynicotinic acid Keywords: acylation; annulation, heterocyclic-[6]; esterification, of substituted monobasic acids; hydrolysis, esters and lactones; stirrers, magnetic

2,4,5-Triaminonitrobenzene intermediate: 1,5-Dichloro-2,4-dinitrobenzene intermediate: 1,5-Diamino-2,4-dinitrobenzene product: 2,4,5-Triaminonitrobenzene Keywords: nitration; reduction, NO2 NH2; replacement reactions, halogen by amino; 1,5-dichloro-2,4-dinitrobenzene, skin irritant

Monitoring the aerosol component of the lowest 10 km of the atmosphere at UV wavelengths (300 - 400 nm) is an important part of the High Resolution Fly's Eye astrophysics experiment. Our method of atmospheric monitoring uses a frequency tripled YAG laser and a steering system that can point the beam anywhere in the sky. The same detector that measures scintillation light from high energy cosmic rays also measures light scattered from this laser system over a range of laser energies, geometries, and polarizations. This paper describes the technique, the laser system, and some recent measurements.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

C 33 H 25 N 3 O cristallise dans P2 1 /n avec a=10,599, b=14,286 et c=16,175 A, β=94,31 o , Z=4; affinement jusqu'a R=0,034. Le triazole est plan. Pas de longueurs ou angles de liaison inhabituels

In 1984, less than two decades after its discovery, a review described the dye laser as one of the most useful and practical of tunable coherent sources. Laser dye activity was presumed to reflect a casual relationship with various ancillary properties including photostability, solubility and other interactions with solvent, fluorescence quantum yield, molar extinction of absorption, and minimal overlap of fluorescence with onset of absorption spectral regions, (S-S) and triplet-triplet (T-T). Bathochromic and hyperchromic shifts were introduced by the substitution of auxochromic and antiauxochromic groups but this benefit was often offset by the ability of certain groups, e.g. nitro, cyano, and heavy atoms, to quench laser activity. Since the known dyes were each deficient in one or more properties the search for new structures to offer superior performance standards was undertaken. Keywords: Laser action in pyrromethene-BF2 complex, Synthesis, Boron trifluoride, TMP, PMP, HMP, PMDEP, Chlorosulfonation, PMPDS, Condensation.

N-nitro- and N-nitrosopipecolic acid were converted to 1-nitro- and 1-nitroso-2-aminopiperidine. The amines were isolated as methyl carbamate derivatives