Cosmic-ray Showers Research Articles

Upper limits for Northern Hemisphere 10 to the 15th eV gamma-ray sources

view Abstract Citations (8) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Upper limits for northern hemisphere 10 15 eV gamma-ray sources. Baltrusaitis, R. M. ; Cassiday, G. L. ; Cooper, R. ; Elbert, J. W. ; Gerhardy, P. R. ; Loh, E. C. ; Mizumoto, Y. ; Sokolsky, P. ; Sommers, P. ; Steck, D. ; Wasserbaech, S. Abstract Flux limits in the range 10-13 to 10-12cm-2s-1 have been obtained by observing Cerenkov flashes from small air showers. Simultaneous drift scans by the 67 mirror units of the Utah Fly's Eye gave nearly full coverage of the northern hemisphere. During 1983, a 3.5 σ excess of showers was observed during the phase interval 0.2 - 0.3 of the 4.8 hr period of Cygnus X-3, but no excess was found in 1984 observations. Publication: The Astrophysical Journal Pub Date: October 1985 DOI: 10.1086/163511 Bibcode: 1985ApJ...297..145B Keywords: Gamma Ray Astronomy; Northern Sky; X Ray Sources; Cerenkov Radiation; Cosmic Ray Showers; Cygnus Constellation; Astrophysics full text sources ADS | data products SIMBAD (1)

Search for heavy long-lived particles in high-energy cosmic rays

We present the results of an experimental search for energetic particles which arrive at sea level delayed with respect to the shower front, with an order of magnitude greater exposure than previous experiments. The experiment was sensitive to showers from cosmic rays between ${10}^{5}$ and ${10}^{7}$ GeV per nucleus. Events with signals greater than 20 equivalent particles and delayed more than 20 ns were observed and studied. A four-dimensional Monte Carlo simulation of cosmic-ray showers combined with accelerator calibration data showed that the observed events as well as previously reported observations of this type can be accounted for by rare fluctuations in signals from low-energy hadrons in the air shower. No evidence for the existence of heavy long-lived particles in air showers was found. We set an upper limit to the flux of these particles at the 90% confidence level of 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}12}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$${\mathrm{sr}}^{\mathrm{\ensuremath{-}}1}$${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$.

Composition of cosmic-ray nuclei from boron to nickel for 1200 to 2400 MeV per nucleon

view Abstract Citations (17) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Composition of cosmic-ray nuclei from boron to nickel for 1200 to 2400 MeV per nucleon Dwyer, R. ; Meyer, P. Abstract Balloon-borne measurements of cosmic-ray nuclear abundances for Z = 5-28 and energies 1.2-1.4 GeV/nucleon, obtained using the scintillation/Cerenkov-counter telescope and multiwire proportional counter described by Dwyer et al. (1984) on four flights from Texas and Oklahoma during 1973-1975, are reported. The data are presented in tables and graphs and compared with published observations. Charge separation (sigma = 0.2 units for Fe) and exposure factor (38 sq m sr h) are attained, and the findings are found to be in good agreement with the predictions of a simple leaky-box model of the Galaxy and a pure exponential path-length distribution, although a nested-leaky-box model with some truncation is possible. The delay between e-process nucleosynthesis and cosmic-ray acceleration is estimated on the basis of the Co abundance at greater than 100 d and probably greater than 100,000 yr. Publication: The Astrophysical Journal Pub Date: July 1985 DOI: 10.1086/163310 Bibcode: 1985ApJ...294..441D Keywords: Abundance; Cosmic Ray Showers; Galactic Cosmic Rays; Heavy Nuclei; Particle Acceleration; Particle Telescopes; Balloon-Borne Instruments; Cerenkov Counters; Energetic Particles; Energy Spectra; High Energy Interactions; Interstellar Chemistry; Nuclear Fusion; Proportional Counters; Scintillation Counters; Astrophysics full text sources ADS |

Measurements of the response of a hadronic calorimeter to beams of pions and protons of 1–10 GeV/ c momenta

An ionization calorimeter was studied with a test beam at the Brookhaven Alternating Gradient Synchrotron. The purpose of the experiment was to calibrate the response of a similar but larger cross section calorimeter used to study high energy cosmic ray showers at the University of Maryland, College Park, Maryland. The beam momenta were between 1 and 10 GeV/ c. Results of measurements of (1) the mean pulse height from a scintillator at different depths in the calorimeter, (2) the frequency of occurrence of very rare events with pulse heights many times the mean pulse height and (3) the correlation of pulse heights from several scintillators at different depths are presented and discussed.

An investigation of cosmic-ray shower depths of maximum using the atmospheric Cerenkov pulse-width technique

This paper discusses measurements of depths of maximum obtained by the use of the width of pulses of Cerenkov radiation produced by extensive air showers having sea-level sizes in the range 6*105-107 particles. These new data are analysed with the assistance of simulated pulse shapes incorporating actual instrumental responses. A discussion of the interpretation of this analysis emphasising selection effects of the Cerenkov detectors and of the particle array is given.

Poisson branching point processes

We investigate the statistical properties of a special branching point process. The initial process is assumed to be a homogeneous Poisson point process (HPP). The initiating events at each branching stage are carried forward to the following stage. In addition, each initiating event independently contributes a nonstationary Poisson point process (whose rate is a specified function) located at that point. The additional contributions from all points of a given stage constitute a doubly stochastic Poisson point process (DSPP) whose rate is a filtered version of the initiating point process at that stage. The process studied is a generalization of a Poisson branching process in which random time delays are permitted in the generation of events. Particular attention is given to the limit in which the number of branching stages is infinite while the average number of added events per event of the previous stage is infinitesimal. In the special case when the branching is instantaneous this limit of continuous branching corresponds to the well-known Yule–Furry process with an initial Poisson population. The Poisson branching point process provides a useful description for many problems in various scientific disciplines, such as the behavior of electron multipliers, neutron chain reactions, and cosmic ray showers.

First observation of gamma-rays from VELA X-1 at energies greater than 3 X 10 to the 15th eV

view Abstract Citations (95) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS First observations of gamma-rays from VELA X-1 at energies greater than 3x10 15 eV. Protheroe, R. J. ; Clay, R. W. ; Gerhardy, P. R. Abstract The first observation of gamma-rays from Vela X-1 is reported. Data from the Buckland Park air shower array contain an excess of events from within 4 degrees if Vela X-1 with characteristics of gamma-ray initiated showers. These excess events are in phase with the orbital period. The probability of this detection occurring by chance is approximately 0.0001. The time-averaged gamma-ray flux above 3 x 10 to the 15th eV is (9.3 + or -3.4) x 10 to the -11th photons/sq m/s, corresponding to a luminosity of approximately 2 x 10 to the 34th erg/s per decade of energy at 3 x 10 to the 15th eV. Publication: The Astrophysical Journal Pub Date: May 1984 DOI: 10.1086/184267 Bibcode: 1984ApJ...280L..47P Keywords: Binary Stars; Cosmic Ray Showers; Energetic Particles; Gamma Rays; X Ray Sources; X Ray Stars; Luminosity; Probability Distribution Functions; Stellar Radiation; Space Radiation full text sources ADS | data products SIMBAD (2)

Observation of an Excess of Cosmic Ray Showers from the Direction of Centaurus A

An analysis of recent data from the Adelaide cosmic ray shower array suggests that an excess of events may have been observed to come from the general direction of Centaurus A. These data are presented and discussed together with directional data from other previous experiments.

Examination of a Proposed Technique for the Economical Detection and Analysis of Ultra-high Energy Cosmic Ray Showers

A study has been made of a recently suggested scheme for the economical detection and analysis of ultra-high energy cosmic ray showers. It is demonstrated that the scheme should be feasible, particularly if detectors are used to sample the y-ray component of the showers.

Cosmic Ray Anisotropy and the Knee of the Energy Spectrum

The knee of the cosmic:ray energy spectrum occurs at an energy slightly below 101 6 eV. At a similar energy significant changes are found in cosmic ray shower development and anisotropy. It is suggested that these changes can be understood if there is a general proton dominated cosmic ray flux along our spiral arm from outer galactic regions, which is exceeded by an iron dominated flux from the opposite spiral arm direction at energies between ~ 1014 and ~ 101 7 eV.

Observation of a Burst of Cosmic Rays at Energies above 7×1013eV

The authors report on an unusual simultaneous increase in the cosmic-ray shower rate at two recording stations separated by 250 km. The event lasted for 20 s. This event was the only one of its kind detected in three years of observation. The duration and structure of this event is different from a recently reported single-station cosmic-ray burst. The simultaneity of the coincident event suggests that it was caused by a burst of cosmic gamma rays. There is a possibility that this event may be related to the largest observed glitch of the pulsar in the Crab Nebula.

The relation of the lateral distribution of Cerenkov light from cosmic-ray showers to the distance of maximum development

The lateral distribution of Cerenkov light intensity from EAS at sea level has been calculated and its dependence on the distance to maximum development, Hm, investigated. The distribution separates into two regions: outside approximately 125 m radius, the intensity Q decreases as R- gamma with gamma dependent on Hm as found previously; more important, inside 125 m, the steepness decreases markedly for showers with large values of Hm. Several functional forms, for example an exponential Q(R) approximately e-bR and a power law (R+R0)- gamma as well as the intensity ratio Q(50)/Q(150), were tried to define the shape in this region. The parameter b and this intensity ratio are equally suitable estimators for Hm les than 5 km. For Hm>or approximately=5 km, where the shape becomes sensitive to the late development of the shower, to the presence of aerosols and to the photocathode spectral response, the ratio is preferred. Typical errors expected are Delta Hm>or approximately=0.4 km below 4 km, increasing to >or approximately=1 km near Hm approximately 7 km. Differences between this theory and that of McComb and Turver (1982) are discussed.

The array-density spectrum of low-energy cosmic-ray showers

Measurements have been made of the array-density spectrum of cosmic-ray showers in the sea-level size range from 3*104 to 106 particles. The index of the power-law spectrum is roughly constant below 3*105 particles but increases rapidly above this size. This increase is consistent with previous work in the range 3*105 to 107 particles.

Fast large aperture camera and data acquisition system with applications in astrophysics, particle physics and nuclear medicine

A fast large aperture multielement imaging camera has been developed to record Cherenkov light spots produced in the atmosphere by cosmic ray showers. The camera may have possible applications in other branches of astrophysics, in particle physics and in nuclear medicine. The camera is capable of simultaneously digitizing the transient outputs (20 ns) of 37 phototubes, each into an 8 bit byte while also capturing a further 27 bytes of system housekeeping data. The 64 bytes are written onto magnetic tape in 114 μs. The throughout rate of the camera is therefore very high. The hardware of the imaging system and its associated data acquisition devices are described in detail.

Detection of 2 X 10 to the 15th to 2 X 10 to the 16th eV gamma-rays from Cygnus X-3

view Abstract Citations (327) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of 2 X l0 l5 to 2 X 10 16 eV gamma-rays from Cygnus X-3. Samorski, M. ; Stamm, W. Abstract Kiel, West Germany air shower experiment data are analyzed with a view to the detection of showers from Cyg X-3, with a measurement resolution of 1 deg and an on-source observation time of 3838 hr over a sensitive area of 2800 sq m. In addition to a 4.4-sigma excess of showers from the direction of delta = 40.9 + or - 1.5 deg and alpha = 307.8 + or - 2.0 deg, the time-averaged analysis indicates the typical 4.8-hr modulation of the excess showers. The time-averaged integral gamma-ray flux derived corresponds to a luminosity of 6 x 10 to the 36th ergs/sec in the 2 x 10 to the 15th-2 x 10 to the 16th eV energy region, establishing this as the first experimental evidence for a clearly identified gamma-ray point source which emits at energies greater than 10 to the 15th eV. Publication: The Astrophysical Journal Pub Date: May 1983 DOI: 10.1086/184021 Bibcode: 1983ApJ...268L..17S Keywords: Cosmic Ray Showers; Cygnus Constellation; Energetic Particles; Gamma Ray Astronomy; Periodic Variations; X Ray Sources; Angular Resolution; Energy Spectra; Luminosity; Particle Flux Density; Photon Density; Space Radiation full text sources ADS | data products SIMBAD (1)

Possible mechanisms for the origin of the cosmic-ray showers coming from the direction of the Crab pulsar

The authors' previous claim (1980, 1981) for an excess of cosmic-ray showers coming from the general direction of the Crab nebula has been strengthened by observation of the effect in other data not examined previously. The nature of the particles responsible for the showers is not clear. There is a reduced muon content, suggestive of primary gamma rays (Egamma approximately=1016 eV) but protons cannot be ruled out. If photons are responsible, a sharp cut-off in the energy spectrum above a few times 1016 eV is indicated in view of the non-observation of a signal in other experiments in this energy range.

Cosmic Ray Showers at 1016 eV

A summary is made of some cosmic ray shower results obtained at the University of Adelaide Buckland Park air shower array. It is demonstrated that a number of air shower parameters undergo appreciable changes at common shower sizes.

Comment on the Cosmic Ray Energy Spectrum in the Light of Results from Atmospheric Cerenkov Studies

New information has recently become available on the development of cosmic ray showers in the atmosphere. This information is used to show that the energy spectrum of cosmic rays must exhibit more pronounced structure than previously thought at energies of about 10'6 eV. Possible interpretations of this structure are discussed

The mass composition of primary cosmic rays of energy 6×1015-2×1018eV

Measurements of the mean and fluctuation in the depth of cascade maximum of large cosmic-ray showers are reported. These are compared with computer simulation predictions for iron nucleus and proton primaries incorporating a range of models of the hadronic interaction. The authors conclude that the primary composition comprises predominantly iron-like nuclei at 1016 eV with an increasing proportion of lighter nuclei at higher energies.

Angular and energy distributions of charged particles in electron-photon cascades in air

Monte-Carlo simulations of the development of 100 GeV photon-initiated cascades in the atmosphere have been used to predict the energy spectra and angular distributions of charged particles in electron-photon showers as a function of shower age. The lateral spread of the particles and their spread in time were also studied, in rather less detail, and a track length integral which measures the angular deflections produced by a magnetic field is given. Approximate formulae are given to describe these distributions. Particles of energy below about 15 MeV are not included in the distributions, as the main intended application is to the study of Cerenkov radiation from cosmic-ray showers, although particles were actually followed down to 0.05 MeV.