Cosmic-ray Showers Research Articles

The total and jet photoproduction cross sections at HERA and Fermilab energies

We show that the hadronic structure of the photon can lead to a significant rise in the total and jet photoproduction cross sections at HERA and Fermilab energies. We present our predictions for the total and jet photoproduction cross sections for the forthcoming Fermilab E683 and ZEUS and H-1 experiments at the HERA collider. We discuss the relevance of the hadronic character to the anomalous muon content recently observed in cosmic ray showers associated with point sources such as Cygnus X-3, Hercules X-1 and the Crab Nebula.

The total and jet photoproduction cross sections at HERA and Fermilab energies

We show that the hadronic structure of the photon can lead to a significant rise in the total and jet photoproduction cross sections at HERA and Fermilab energies. We present our predictions for the total and jet photoproduction cross sections for the forthcoming Fermilab E683 and ZEUS and H-1 experiments at the HERA collider. We discuss the relevance of the hadronic character to the anomalous muon content recently observed in cosmic ray showers associated with point sources such as Cygnus X-3, Hercules X-1 and the Crab Nebula.

A search of the northern sky for ultra-high-energy point sources

view Abstract Citations (36) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Search of the Northern Sky for Ultra--High-Energy Point Sources Alexandreas, D. E. ; Berley, D. ; Biller, S. ; Burman, R. L. ; Cady, D. R. ; Chang, C. Y. ; Dingus, B. L. ; Dion, C. L. ; Dion, G. M. ; Ellsworth, R. W. ; Freedman, S. J. ; Fujikawa, B. K. ; Goodman, J. A. ; Haines, T. J. ; Hoffman, C. M. ; Krakauer, D. A. ; Kwok, P. W. ; Lu, X. -Q. ; Nagle, D. E. ; Potter, M. ; Sandberg, V. D. ; Sinnis, C. ; Stark, M. J. ; Vishwanath, P. R. ; Yodh, G. B. ; Zhang, W. P. Abstract A search has been made for steady emission of ultra-high-energy radiation from individual point sources over most of the northern sky. Over 2 x 10^8^ air showers induced by primary particles of energy greater than about 10 TeV were recorded from 1986 April until 1991 May by the CYGNUS air shower array. No statistically significant excess above the background from the isotropic flux of cosmic rays was found for any direction in the sky from 0^deg^ to 80^deg^ declination. In addition, 49 specific potential sources were examined, and none showed a statistically significant excess of events. 90% confidence level flux upper limits are established for the continuous emission from these sources; for a source that transits the zenith, a representative upper limit corresponds to an integral flux above 40 TeV of about 1.7 x 10^-13^ cm^-2^ s^-1^ (0.5% of the cosmic-ray flux within an angular area of 1.8 x 10^-3^ sr) assuming a power-law energy spectrum with a differential spectral index of -2.7. Publication: The Astrophysical Journal Pub Date: December 1991 DOI: 10.1086/186239 Bibcode: 1991ApJ...383L..53A Keywords: Cosmic Ray Showers; Gamma Rays; Northern Sky; Point Sources; Sky Surveys (Astronomy); Energy Spectra; Particle Energy; Particle Flux Density; Space Radiation; COSMIC RAYS: GENERAL; GAMMA RAYS: GENERAL full text sources ADS | data products SIMBAD (44) NED (2)

A method to measure the γ-ray content in VHE cosmic ray showers

An experimental technique is presented to determine the effectiveness of methods to tag photon initiated air showers and reject hadron initiated ones. The technique is based on the rate reduction in the Moon direction. With a photon energy threshold below or equal to 1 TeV, with an angular resolution of a few mrad and being insensitive to visible light, the proposed CLUE detector allows a wide and original physics program. In particular the direct measurement of the fraction of primary photons in the continuum of the cosmic ray flux is feasible with adequate statistics in a few months of data taking.

Observations of ultra-high-energy photons from Cygnus X-3

view Abstract Citations (14) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of Ultra--High-Energy Photons from Cygnus X-3 Muraki, Y. ; Shibata, S. ; Aoki, T. ; Mitsui, K. ; Okada, A. ; Ohashi, Y. ; Kobayakawa, K. ; Kojima, H. ; Kitamura, T. ; Kato, Y. ; Takahashi, T. ; Nakamura, I. Abstract Extensive air showers coming from the Cygnus X-3 region are analyzed using the van der Klis and Bonnet-Bidaud ephemeris. A 4.7 sigma excess has been observed in the phase bin 0.25-0.3. The maximum excess is seen when a muon cut is applied to the showers, which indicates a slightly muon poor property. The flux is estimated to be (2.7 + or - 0.5) x 10 to the -14th/sq cm s for the showers Ne greater than 200,000. DC excesses are observed at the time of the radio burst of Cygnus X-3 in June 1989. Publication: The Astrophysical Journal Pub Date: June 1991 DOI: 10.1086/170085 Bibcode: 1991ApJ...373..657M Keywords: Cosmic Ray Showers; Gamma Ray Bursts; Interstellar Radiation; X Ray Binaries; X Ray Spectra; Cygnus Constellation; Muons; Nuclear Astrophysics; Radiation Detectors; Radio Bursts; Stellar Mass; Space Radiation; COSMIC RAYS: GENERAL; GAMMA RAYS: BURSTS; X-RAYS: BINARIES full text sources ADS | data products SIMBAD (1)

Detection of ultraviolet Cherenkov light from high energy cosmic ray atmospheric showers: a field test

Abstract We present the results of a test with a prototype apparatus aimed to detect the ultraviolet Cherenkov light in the wavelength range 2000–2300 A, emitted by high energy cosmic ray showers. The system consists of a gas proportional chamber, with TMAE vapour as the photosensitive element, placed on the focal plane of a 1.5 m diameter parabolic mirror. The test was done during the summer of 1989 with cosmic ray showers seen in coincidence with the EAS-TOP experiment, an extended atmospheric shower charged particle array now being exploited at Campo Imperatore, 1900 m above sea level, on top of the Gran Sasso underground Laboratory of INFN. The results were positive and show that a full scale ultraviolet Cherenkov experiment with good sensitivity, angular resolution and virtually no background from moonlight or even daylight can be envisaged.

Baryons in cosmic ray showers and the interaction depth

Guided by a topological model of baryon production in high-energy collisions, we consider the qualitative effect of secondary baryon production in cosmic ray showers. We argue that the smaller range of baryons, relative to mesons, will tend to reduce the depth of the shower maximum X max without reducing the variation in this observable. This effect could reduce significantly the descrepancy between Fly's Eye data and existing cosmic ray shower Monte Carlo models for incoming protons, and we argue that this effect is unlikely to be washed out by the baryon energy spectrum being soft. We also comment on the likelihood of baryon-rich events mimicking the Centauro data.

Is the cosmic-ray hadron shower a fractal?

The possible fractal nature of trajectories drawn by cosmic-ray particles in the atmosphere is investigated. In the course of the propagation of a primary cosmic-ray particle from the top of the atmosphere to sea level, it develops a ramified hadron shower, which is constituted mainly of pions and kaons. These hadrons are multiply produced at every collision of the hadron with an air nucleus. If the cross section corresponding to a definite multiplicity of hadrons decreases with the increase of energy E, in such a manner as to be reciprocally proportional to some powers of E, the resultant pattern of the shower possibly becomes fractal. Since the total interaction cross section is considered to be a superposition of many fundamental cross sections each of which corresponds to a definite multiplicity, the actual hadron shower can be interpreted as a superposition of many fractals each of which has an unique fractal dimension. The total energy of the shower has appeared to obey Laplace's equation under a quasi-stationary condition. Some ramified patterns of the cosmic-ray hadron shower are derived with computers.

A photosensitive chamber for cosmic-ray spectroscopy

We present details of the construction and performance of a set of photosensitive chambers intended to detect ultraviolet Cherenkov light in cosmic-ray shower experiments. The particularly simple design of these chambers allows mass production and outdoor operation. Detection efficiency and sensitivity to a few photoelectrons have been measured at the predicted level. Bench test results are shown and performances in true outdoor operation are presented.

A photodensitometric method for determining the structure of cosmic ray showers in emulsion chambers

We describe a photodensitometric method for the study of the longitudinal and lateral development, as well as the energy determination, of high energy showers in an emulsion chamber. These showers are produced by the nuclear interaction of cosmic ray particles with the atmosphere and lead in the chamber. In this paper the apparatus is described and some preliminary results are given to demonstrate the technique.

Search for >200 TeV photons from Cygnus X-3 in 1988 and 1989.

Over a period of 16 months from April 1988 to August 1989, we have monitored the flux of cosmic-ray showers with energies above 2{times}10{sup 14} eV. We used a two-level array of scintillators covering an area of 3{times}10{sup 4} m{sup 2}. Counters on the surface measure the size and direction of each shower while counters buried 3 m beneath the surface sample the muons. By selecting showers with relatively few muons (less than one-tenth the average) the background of hadron-induced showers should be reduced by a factor of 150 or more while showers started by {gamma} rays should not be affected by this cut. We find no evidence for an excess from the direction of Cygnus X-3 either in ordinary showers or in muon-poor showers. For energies above 2{times}10{sup 14} eV, with 90% confidence, we find the excess flux of cosmic rays from the direction of Cygnus X-3 to be less than 1.3{times}10{sup {minus}13} cm{sup {minus}2}s{sup {minus}1} and the flux of photons (assuming they produce muon-poor showers) to be less than 1.5{times}10{sup {minus}14} cm{sup {minus}2}s{sup {minus}1}. This limit is substantially below the level of signals reported by earlier work. The period of observation included the intense radio bursts of Junemore » and July 1989. A portion of the data covering the 77-day period surrounding these events also showed no evidence for an excess.« less

The akeno spica array and analysis of 1986 from her X-1

A new UHE γ-ray air shower array, referred to as SPICA (the SPecial Instrument for Cosmic ray Astrophysics), is being operated at Akeno. The SPICA array utilizes both scintillation detectors and proportional counters for sampling both the electromagnetic and muonic components of cosmic ray showers. Fast timing PMTs with CAMAC/TDC readout are now used, and an off-line shower front ‘curvature’ correction implemented which improves the median angular resolution of SPICA to better than 1° under certain conditions. Inspired by the discovery of an anomalous pulsar period from Her X-1 and the unexpectedly high percentage of muons in the showers that exhibit this periodicity, we are searching for UHE γ-ray emission in the SPICA data from Her X-1.

Optical characteristics of the whipple observatory TeV gamma-ray imaging telescope

In TeV γ-ray astronomy, large mirrors are used to collect Cerenkov light from electromagnetic cascades in the atmosphere in order to obtain low energy thresholds. The flux sensitivity of TeV γ-ray detectors is limited by background due to Cerenkov light bursts from isotropic, cosmic-ray showers which are much more numerous than γ-ray showers. It has recently been established that most of this background can be eliminated on the basis of the shapes of Cerenkov light images on the focal plane of a telescope. In order for this technique to work, the light collector must have adequate resolution over a relatively wide field of view. In this paper, the optical characteristics of the 10 m reflector used in the imaging detection of the Crab Nebula are examined and contrasted with those of a standard parabolic design. This 10 m reflector has a unique (Davies-Cotton) design with small spherical facet mirrors placed on spherical support structure with radius equal to exactly 1/2 the curvature radius of the facet mirrors. The off-axis focusing properties of this type of telescope have not been examined previously.

Observations of steady flux of PeV-energy extensive air showers from Cygnus X-3 during 1984-1986

view Abstract Citations (22) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of Steady Flux of PeV--Energy Extensive Air Showers from Cygnus X-3 during 1984--1986 Tonwar, S. C. ; Gopalakrishnan, N. V. ; Rajeev, M. R. ; Sreekantan, B. V. Abstract Data taken with a 24-detector extensive-air-shower (EAS) array, operating at Ooty since June, 1984, have been used to search for excess of EASs of energy greater than 250 TeV from the direction of binary X-ray source Cyg X-3. The data show a time-averaged excess in the number of showers from this direction, over the background determined from other regions of the sky having the same declination. The excess is most prominent among older showers having a flatter lateral distribution. A part of this excess shows up significantly in the phase region, 0.6-0.8 in the 4.8-hr periodicity analysis. These observations correspond to an integral flux of (7.16 + or - 3.15) x 10 to the -13th/sq cm sec at energies greater than 250 TeV and of (1.04 + or - 0.44) x 10 to the -13th/sq cm sec at energies greater than 2.5 PeV. The observations confirm, for the first time, results reported by the Kiel group (Samorski and Stamm, 1983) of a directional excess from the direction of Cyg X-3, without requiring the 4.8-hr periodicity analysis as was necessary in many of the other experiments reporting positive signals. This emphasizes the advantage of good angular resolution for such studies. Publication: The Astrophysical Journal Pub Date: July 1988 DOI: 10.1086/185215 Bibcode: 1988ApJ...330L.107T Keywords: Cosmic Ray Showers; Gamma Rays; Neutron Stars; Particle Flux Density; X Ray Binaries; Angular Resolution; Electron Emission; Electron Energy; Histograms; Light Curve; Relativistic Particles; Space Radiation; GAMMA RAYS: GENERAL; X-RAYS: SOURCES full text sources ADS | data products SIMBAD (1)

The Haleakala gamma ray observatory

A 10 m 2 multi-mirror telescope for observing Cherenkov light signals from atmospheric cascades is now operating at Mount Haleakala, Maui, Hawaii. It differs from other atmospheric Cherenkov detectors in accepting pulses that originate from single photoelectrons, employing two sets of 18 optically independent phototubes in a logic system with nanosecond time resolution to reject ambient light from the night sky. With an angular aperture of 1.3 × 10 −4 sr, cosmic ray showers are observed at a rate of ∼ 0.5 hz at the zenith, with nearly complete rejection of ambient light. This rate for hadronic showers implies an effective threshold near 100 GeV for electromagnetic showers. Two regions of the sky, one centered on the source and the other separated by from it by 3.6° are simultaneously monitored. Examples of observations of episodic and periodic (pulsar) sources are given.

A Search for Tachyons in Cosmic Ray Showers

A search has been made for tachyons associated with cosmic ray showers of energies about 1015 eV by searching for any precursor effects observed in plastic scintillator detectors. Detection thresholds well below most other similar experiments have been reached but no statistically significant effects have been found.

Statistical properties of cosmic-ray showers at ground level determined from photomultiplier-tube background registrations.

The fluctuations of cosmic-ray particles resulting from extensive air showers at ground level are well described by the two-parameter Poisson-driven Yule-Furry and negative-binomial counting probability distributions. The background signal from a single photomultiplier tube has been used to experimentally verify these results with remarkable precision, in spite of the simplicity of the underlying pure-birth stochastic process. Counting distributions from three different photomultiplier-tube detectors operated in the dark are presented, together with the theoretical predictions. Probability distributions of interevent times have also been obtained and these are found to be consistent with the observed clustering properties at the detector output. Our approach is expected to be of importance in quantum optics where cosmic-ray-shower particles can pose a significant limitation on the detection of squeezed light.

The proton-air cross-section at 1016 eV

A study of the Cerenkov light lateral distribution function for cosmic-ray showers with energies of about 1016 eV has been used to determine the distribution of depths of shower maximum at these energies. This distribution has an exponential tail due to fluctuations in the depths of early interactions of the proton primary component. The form of this tail may be used to infer an inelastic proton-air cross-section of (590±70) mb at ≈1016 eV.

Detector system for the measurement of the muon array density spectrum in cosmic ray showers

A Monte Carlo simulation is performed in order to find the optimum detector configuration for measurements of the array density spectrum of muons ( E > 1 GeV) in extensive air showers. Preliminary measurements were done with a pair of thin plastic scintillation detectors.

An economical method for studying very large extensive air showers

Abstract A detector suitable for use in the study of cosmic-ray showers above 1019 eV has been operated at a remote location, within the Haverah Park air shower array, under the control of a computer located at the centre of the array. A microprocessor handled pulse height and timing data at the detector and also responded to command signals transmitted via a 2-way radio link from the computer by initiating the transmission of detector data back to the computer. The computer then found those measurements which corresponded to air showers by looking for matching times between the remote detector and the central detector of the array. The timing measurements were derived from broadcast television signals and were accurate enough to allow the incident directions of air showers to be calculated with an error of less than ±3.5°.