108 research outputs found
Evidence for 10^18-eV neutral particles from the direction of Cygnus X-3
Journal ArticleAnalysis of the cumulative Fly's Eye data reveals an excess of air showers from the direction of Cygnus X-3 at energies above 0.5 x 10^18 eV. No point source has previously been identified at such high energies. The probability of this excess arising as a chance clustering of isotropic cosmic rays is 6 . 5 x 10^-4 . The inferred signal flux is (2.0 ± 0.6) x 10&-17 particles/cm2 s. The Cygnus X-3 4.8-h periodicity is weakly present in the data
The structure of EAS at E 0.1 EeV
The ratio of extensive air showers (EAS) total shower energy in the electromagnetic channel (E em) to the size of the shower at maximum development (N max) from a direct measurement of shower longitudinal development using the air fluorescence technique was calculated. The values are not inconsistent with values based upon track length integrals of the Gaisser-Hillas formula for shower development or the known relation between shower energy and size at maximum for pure electromagnetic cascades. Using Linsley's estimates for undetected shower energy based on an analysis of a wide variety of cosmic ray data, the following relation for total shower energy E vs N max is obtained. The Gaisser Hillas implied undetected shower energy fractions
Proton-air inelastic cross section at S(1/2) = 30 TeV
The distribution of the maxima of high energy cosmic ray induced extensive air showers in the atmosphere was measured as a function of atmospheric depth. From the exponential tail of this distribution, it was determined that the proton-air inelastic cross section at 30 TeV center-of-mass energy to be 540 + or - 40mb
All sky Northern Hemisphere 10(15) EV gamma-ray survey
Flux limits in the range 10 to the minus 13th power-10 to the minus 12 power/sq cm/s have been obtained by observing Cerenkov flashes from small air showers. During 1983, a 3.5 sigma excess of showers was observed during the phase interval 0.2 to 0.3 of the 4.8h period of Cygnus X-3, but no excess was found in 1984 observations
500 TeV gamma rays from Hercules X-1
A signal (chance probability = .0002) with the 1.24 s period of Hercules X-1 has been observed using the Utah Fly's Eye. The signal's relatively long period and high shower energy conflict with some popular models of particle acceleration by pulsars. Optical and X-ray data suggest a picture in which energetic particles produce multi-TeV gamma rays by collisions with Hercules X-1's accretion disk
Limits on deeply penetrating particles in the 10(17) eV cosmic ray flux
Deeply penetrating particles in the 10 to the 17th power eV cosmic ray flux were investigated. No such events were found in 8.2 x 10 to the 6th power sec of running time. Limits were set on the following: quark-matter in the primary cosmic ray flux; long-lived, weakly interacting particles produced in p-air collisions; the astrophysical neutrino flux. In particular, the neutrino flux limit at 10 to the 17th power eV implies that z, the red shift of maximum activity is 10 in the model of Hill and Schramm
Energy calibration of the fly's eye detector
The methods used to calibrate the Fly's eye detector to evaluate the energy of EAS are discussed. The energy of extensive air showers (EAS) as seen by the Fly's Eye detector are obtained from track length integrals of observed shower development curves. The energy of the parent cosmic ray primary is estimated by applying corrections to account for undetected energy in the muon, neutrino and hadronic channels. Absolute values for E depend upon the measurement of shower sizes N sub e(x). The following items are necessary to convert apparent optical brightness into intrinsical optical brightness: (1) an assessment of those factors responsible for light production by the relativistic electrons in an EAS and the transmission of light thru the atmosphere, (2) calibration of the optical detection system, and (3) a knowledge of the trajectory of the shower
Study of composition of cosmic rays with energy .7 E 3 Ee
The longitudinal shower development of extensive air showers (EAS) observed in the fly's eye is used to determine the distribution of X sub max, the depth in the atmosphere of the EAS maximum. Data and Monte Carlo simulations of proton and iron primaries are compared. A substantial contribution from light primaries is noted
Atmospheric Muon Flux at Sea Level, Underground, and Underwater
The vertical sea-level muon spectrum at energies above 1 GeV and the
underground/underwater muon intensities at depths up to 18 km w.e. are
calculated. The results are particularly collated with a great body of the
ground-level, underground, and underwater muon data. In the hadron-cascade
calculations, the growth with energy of inelastic cross sections and pion,
kaon, and nucleon generation in pion-nucleus collisions are taken into account.
For evaluating the prompt muon contribution to the muon flux, we apply two
phenomenological approaches to the charm production problem: the recombination
quark-parton model and the quark-gluon string model. To solve the muon
transport equation at large depths of homogeneous medium, a semi-analytical
method is used. The simple fitting formulas describing our numerical results
are given. Our analysis shows that, at depths up to 6-7 km w. e., essentially
all underground data on the muon intensity correlate with each other and with
predicted depth-intensity relation for conventional muons to within 10%.
However, the high-energy sea-level data as well as the data at large depths are
contradictory and cannot be quantitatively decribed by a single nuclear-cascade
model.Comment: 47 pages, REVTeX, 15 EPS figures included; recent experimental data
and references added, typos correcte
A High Statistics Search for Ultra-High Energy Gamma-Ray Emission from Cygnus X-3 and Hercules X-1
We have carried out a high statistics (2 Billion events) search for
ultra-high energy gamma-ray emission from the X-ray binary sources Cygnus X-3
and Hercules X-1. Using data taken with the CASA-MIA detector over a five year
period (1990-1995), we find no evidence for steady emission from either source
at energies above 115 TeV. The derived upper limits on such emission are more
than two orders of magnitude lower than earlier claimed detections. We also
find no evidence for neutral particle or gamma-ray emission from either source
on time scales of one day and 0.5 hr. For Cygnus X-3, there is no evidence for
emission correlated with the 4.8 hr X-ray periodicity or with the occurrence of
large radio flares. Unless one postulates that these sources were very active
earlier and are now dormant, the limits presented here put into question the
earlier results, and highlight the difficulties that possible future
experiments will have in detecting gamma-ray signals at ultra-high energies.Comment: 26 LaTeX pages, 16 PostScript figures, uses psfig.sty to be published
in Physical Review
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