4,193 research outputs found
Comparison of AGASA data with CORSIKA simulation
An interpretation of AGASA (Akeno Giant Air Shower Array) data by comparing
the experimental results with the simulated ones by CORSIKA (COsmic Ray
SImulation for KASCADE) has been made. General features of the electromagnetic
component and low energy muons observed by AGASA can be well reproduced by
CORSIKA. The form of the lateral distribution of charged particles agrees well
with the experimental one between a few hundred metres and 2000 m from the
core, irrespective of the hadronic interaction model studied and the primary
composition (proton or iron). It does not depend on the primary energy between
10^17.5 and 10^20 eV as the experiment shows. If we evaluate the particle
density measured by scintillators of 5 cm thickness at 600 m from the core
(S_0(600), suffix 0 denotes the vertically incident shower) by taking into
account the similar conditions as in the experiment, the conversion relation
from S_0(600) to the primary energy is expressed as E [eV] = 2.15 x 10^17 x
S_0(600)^1.015, within 10% uncertainty among the models and composition used,
which suggests the present AGASA conversion factor is the lower limit. Though
the form of the muon lateral distribution fits well to the experiment within
1000 m from the core, the absolute values change with hadronic interaction
model and primary composition. The slope of the rho_mu(600) (muon density above
1 GeV at 600 m from the core) vs. S_0(600) relation in experiment is flatter
than that in simulation of any hadronic model and primary composition. Since
the experimental slope is constant from 10^15 eV to 10^19 eV, we need to study
this relation in a wide primary energy range to infer the rate of change of
chemical composition with energy. keywords: cosmic ray, extensive air shower,
simulation, primary energy estimation PACS number ; 96.40.De, 96.40.PqComment: 30 pages, 15 figures, accepted by Astroparticle Physics at 6. Dec
199
Warm absorber, reflection and Fe K line in the X-ray spectrum of IC 4329A
Results from the X-ray spectral analysis of the ASCA PV phase observation of
the Seyfert 1 galaxy IC 4329A are presented. We find that the 0.4 - 10 keV
spectrum of IC 4329A is best described by the sum of a steep () power-law spectrum passing through a warm absorber plus a strong
reflection component and associated Fe K line, confirming recent results
(Madejski et al. 1995, Mushotsky et al. 1995). Further cold absorption in
excess of the Galactic value and covering the entire source is also required by
the data, consistent with the edge-on galactic disk and previous X-ray
measurements. The effect of the warm absorber at soft X-ray energies is best
parameterized by two absorption edges, one consistent with OVI, OVII or NVII,
the other consistent with OVIII. A description of the soft excess in terms of
blackbody emission, as observed in some other Seyfert 1 galaxies, is ruled out
by the data. A large amount of reflection is detected in both the GIS and SIS
detectors, at similar intensities. We find a strong correlation between the
amount of reflection and the photon index, but argue that the best solution
with the present data is that given by the best statistical fit. The model
dependence of the Fe K line parameters is also discussed. Our best fit gives a
slightly broad ( keV) and redshifted (E keV) Fe K line, with equivalent width 89 33 eV.
The presence of a weak Fe K line with a strong reflection can be reconciled if
one assumes iron underabundances or ionized reflection. We also have modeled
the line with a theoretical line profile produced by an accretion disk. This
yields results in better agreement with the constraints obtained from the
reflection component.Comment: Accepted for publication in The Astrophysical Journal, 10th February
1996 issue; 24 pages and 8 figures + 1 table tared, compressed and uuencoded
(with uufiles
Core structure of EAS in 10(15) to 10(17) eV
With the use of Akeno calorimeter, the attenuation of particles in concrete is analyzed as the function of the shower size of 10 to the 5th power to 10 to the 7th power. The attenuation length does not depend much on the shower size but depends a little on the shower age. The average value is approx. 150 g/sq cm for s = 0.5 to 0.85 and approx. 40 g/sq cm for s = 0.85 to 1.15. These values and their fluctuations are consistent with the equi-intensity curves of extensive air showers (EAS)
Recent progress of GaAsP HPD development for the MAGIC telescope project
Today the Hybrid Photon Detector (HPD) is one of the few low light level
(LLL) sensors that can provide an excellent single and multiple photoelectron
(ph.e.) amplitude resolution. The recently developed HPDs for the MAGIC
telescope project with a GaAsP photocathode, namely the R9792U-40, provide a
peak quantum efficiency (QE) of more than 50% and a pulse width of ~2 nsec. In
addition, the afterpulsing rate of these tubes is very low compared to that of
conventional photomultiplier tubes (PMTs), i.e. the value is ~300 times lower.
Photocathode aging measurements showed life time of more than 10 years under
standard operating conditions of the Cherenkov Telescopes. Here we want to
report on the recent progress with the above mentioned HPDs.Comment: Contribution to the 30th ICRC, Merida Mexico, July 2007 on behalf of
the MAGIC Collaboratio
Development of Atmospheric Monitoring System at Akeno Observatory for the Telescope Array Project
We have developed an atmospheric monitoring system for the Telescope Array
experiment at Akeno Observatory. It consists of a Nd:YAG laser with an
alt-azimuth shooting system and a small light receiver. This system is
installed inside an air conditioned weather-proof dome. All parts, including
the dome, laser, shooter, receiver, and optical devices are fully controlled by
a personal computer utilizing the Linux operating system.
It is now operated as a back-scattering LIDAR System. For the Telescope Array
experiment, to estimate energy reliably and to obtain the correct shower
development profile, the light transmittance in the atmosphere needs to be
calibrated with high accuracy.
Based on observational results using this monitoring system, we consider this
LIDAR to be a very powerful technique for Telescope Array experiments. The
details of this system and its atmospheric monitoring technique will be
discussed.Comment: 24 pages, 13 figures(plus 3 gif files), Published in NIM-A Vol.488,
August 200
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