Techniques for measuring atmospheric aerosols at the High Resolution Fly's Eye experiment

We describe several techniques developed by the High Resolution Fly's Eye experiment for measuring aerosol vertical optical depth, aerosol horizontal attenuation length, and aerosol phase function. The techniques are based on measurements of side-scattered light generated by a steerable ultraviolet laser and collected by an optical detector designed to measure fluorescence light from cosmic-ray air showers. We also present a technique to cross-check the aerosol optical depth measurement using air showers observed in stereo. These methods can be used by future air fluorescence experiments.Comment: Accepted for publication in Astroparticle Physics Journal 16 pages, 9 figure

Momentum Transfer Dependence of Nuclear Transparency from the Quasielastic ^(12)C(e, e'p) Reaction

The cross section for quasielastic ^(12)C(e,e’p) scattering has been measured at momentum transfer Q^2=1, 3, 5, and 6.8 (GeV/c)^2. The results are consistent with scattering from a single nucleon as the dominant process. The nuclear transparency is obtained and compared with theoretical calculations that incorporate color transparency effects. No significant rise of the transparency with Q^2 is observed

Air Fluorescence Relevant for Cosmic-Ray Detection - Summary of the 5th Fluorescence Workshop, El Escorial 2007

High-energy cosmic rays with energies exceeding $10^{17}$ eV are frequently observed by measurements of the fluorescence light induced by air showers. A major contribution to the systematic uncertainties of the absolute energy scale of such experiments is the insufficient knowledge of the fluorescence light yield of electrons in air. The aim of the 5th Fluorescence Workshop was to bring together experimental and theoretical expertise to discuss the latest progress on the investigations of the fluorescence light yield. The results of the workshop will be reviewed as well as the present status of knowledge in this field. Emphasis is given to the fluorescence light yield important for air shower observations and its dependence on atmospheric parameters, like pressure, temperature, and humidity. The effects of the latest results on the light observed from air showers will be discussed.Comment: Nucl. Instr. & Meth. in pres

Evidence for virtual Compton scattering from the proton

In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation

Report of the Working Group on the Composition of Ultra High Energy Cosmic Rays

For the first time a proper comparison of the average depth of shower maximum ($X_{\rm max}$) published by the Pierre Auger and Telescope Array Observatories is presented. The $X_{\rm max}$ distributions measured by the Pierre Auger Observatory were fit using simulated events initiated by four primaries (proton, helium, nitrogen and iron). The primary abundances which best describe the Auger data were simulated through the Telescope Array (TA) Middle Drum (MD) fluorescence and surface detector array. The simulated events were analyzed by the TA Collaboration using the same procedure as applied to their data. The result is a simulated version of the Auger data as it would be observed by TA. This analysis allows a direct comparison of the evolution of $\langle X_{\rm max} \rangle$ with energy of both data sets. The $\langle X_{\rm max} \rangle$ measured by TA-MD is consistent with a preliminary simulation of the Auger data through the TA detector and the average difference between the two data sets was found to be $(2.9 \pm 2.7\;(\text{stat.}) \pm 18\;(\text{syst.}))~\text{g/cm}^2$.Comment: To appear in the Proceedings of the UHECR workshop, Springdale USA, 201

Study of Small-Scale Anisotropy of Ultrahigh Energy Cosmic Rays Observed in Stereo by HiRes

The High Resolution Fly's Eye (HiRes) experiment is an air fluorescence detector which, operating in stereo mode, has a typical angular resolution of 0.6 degrees and is sensitive to cosmic rays with energies above 10^18 eV. HiRes is thus an excellent instrument for the study of the arrival directions of ultrahigh energy cosmic rays. We present the results of a search for anisotropies in the distribution of arrival directions on small scales (<5 degrees) and at the highest energies (>10^19 eV). The search is based on data recorded between 1999 December and 2004 January, with a total of 271 events above 10^19 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.Comment: 4 pages, 3 figures. Matches accepted ApJL versio

The Ursinus Weekly, November 24, 1952

Fall play to be Dec. 5, 6; Ticket sale begins Dec. 1 • Bob Harry to play at senior formal • Freshman rep is sworn in by MSGA • Phys-eds get new teachers • Naval officer to speak here, Dec. 3 • Pre-legal group hears speaker, accepts three new members • Lantern goes to press today; Barbara Wagner designs cover • Messiah seats reserved for 100 students • Constitution changes begun by W.S.G.A. • About 100 students enjoy variety show • Lord Winterton to speak at first forum tomorrow • First Chest drive proceeds small; Two days remain • Help offered for grad study • SWC wins hunt sponsored by Y • Spirit group chooses words for dorm decoration prize • Editorials: Plea to 60 students; What\u27s wrong, men?; Brighter side • Letters to the editor • Two staff members enjoy play preview • Murky for the turkey • Dr. A. Rice attends Atlantic Union sessions • Dickinson hands Bears loss in grid final, 18-6 • Bakermen drop season closer, 6-0 • Former coach plays softball in Korea • Snell\u27s Belles close season by defeating Penn • Marge Merrifield elected captain • Women elect chairmen of table decoration committees • Chess club ties Lansdale • Chi Alpha organizes for Christmas worship service • Bus ads plan discussionhttps://digitalcommons.ursinus.edu/weekly/1507/thumbnail.jp

Measurement of the Flux of Ultrahigh Energy Cosmic Rays from Monocular Observations by the High Resolution Fly's Eye Experiment

We have measured the cosmic ray spectrum above 10^17.2 eV using the two air fluorescence detectors of the High Resolution Fly's Eye observatory operating in monocular mode. We describe the detector, photo-tube and atmospheric calibrations, as well as the analysis techniques for the two detectors. We fit the spectrum to a model consisting of galactic and extra-galactic sources.Comment: 4 pages, 4 figures. Uses 10pt.rtx, amsmath.sty, aps.rtx, revsymb.sty, revtex4.cl

Neutron Star Constraints on the H Dibaryon

We study the influence of a possible H dibaryon condensate on the equation of state and the overall properties of neutron stars whose population otherwise contains nucleons and hyperons. In particular, we are interested in the question of whether neutron stars and their masses can be used to say anything about the existence and properties of the H dibaryon. We find that the equation of state is softened by the appearance of a dibaryon condensate and can result in a mass plateau for neutron stars. If the limiting neutron star mass is about that of the Hulse-Taylor pulsar a condensate of H dibaryons of vacuum mass 2.2 GeV and a moderately attractive potential in the medium could not be ruled out. On the other hand, if the medium potential were even moderately repulsive, the H, would not likely exist in neutron stars. If neutron stars of about 1.6 solar mass were known to exist, attractive medium effects for the H could be ruled out. Certain ranges of dibaryon mass and potential can be excluded by the mass of the Hulse-Taylor pulsar which we illustrate graphically.Comment: Revised by the addition of a figure showing the region of dibaryon mass and potential excluded by the Hulse-Taylor pulsar. 18 pages, 11 figures, latex (submitted to Phys. Rev. C