319 research outputs found
Measurement of energy muons in EAS at energy region larger thean 10(17) eV
A measurement of low energy muons in extensive air showers (EAS) (threshold energies are 0.25, 0.5, 0.75 and 1.38 GeV) was carried out. The density under the concrete shielding equivalent to 0.25 GeV at core distance less than 500 m and 0.5 GeV less than 150 m suffers contamination of electromagnetic components. Therefore the thickness of concrete shielding for muon detectors for the giant air shower array is determined to be 0.5 GeV equivalence. Effects of photoproduced muons are found to be negligible in the examined ranges of shower sizes and core distances. The fluctuation of the muon density in 90 sq m is at most 25% between 200 m and 600 m from the core around 10 to the 17th power eV
Akeno 20 km (2) air shower array (Akeno Branch)
As the first stage of the future huge array, the Akeno air shower array was expanded to about 20 sq. km. by adding 19 scintillation detectors of 2.25 sq m area outside the present 1 sq. km. Akeno array with a new data collection system. These detectors are spaced about 1km from each other and connected by two optical fiber cables. This array has been in partial operation from 8th, Sep. 1984 and full operation from 20th, Dec. 1984. 20 sq m muon stations are planned to be set with 2km separation and one of them is now under construction. The origin of the highest energy cosmic rays is studied
Evaluation of Surface and Flexoelectric Polarizations in Nematic Liquid Crystal using Short Pulse Laser Irradiation
Estimation of Surface and Flexoelectric Polarization in Smectic Liquid Crystal using a Pyroelectric Technique
On a possible photon origin of the most-energetic AGASA events
In this work the ultra high energy cosmic ray events recorded by the AGASA
experiment are analysed. With detailed simulations of the extensive air showers
initiated by photons, the probabilities are determined of the photonic origin
of the 6 AGASA events for which the muon densities were measured and the
reconstructed energies exceeded 10^20 eV. On this basis a new, preliminary
upper limit on the photon fraction in cosmic rays above 10^20 eV is derived and
compared to the predictions of exemplary top-down cosmic-ray origin models.Comment: 3 pages, 1 figure, 2 tables; presented at XIII ISVHECRI, Pylos,
Greec
Separate measurements of the flexoelectric and surface polarization in a model nematic liquid crystal p-methoxybenzylidene-p´-butylaniline : Validity of the quadrupolar approach
The temperature dependences of the surface polarization have been measured at the interface of a conductive glass with both the homogeneously and homeotropically oriented nematic liquid crystal p-methoxybenzylidene-p´-butylaniline. The polarization was found in the field-off regime from the pyroelectric response of a cell to a short laser pulse, absorbed in the bulk of the liquid crystal. The temperature increment was calculated from the measurements of the birefringence induced by the same light pulse. It has been shown that the surface polarization at the homeotropic (mh) and planar (mp) interfaces is directed from an interface into the bulk and from the bulk to an interface, respectively (with a magnitude mh~— 0.3 pC/m and mp' ≈ 0.2 pC/m at 25℃). The experimental data may be explained in terms of the quadrupole model of the order-electric polarization with account of some additional contribution from molecular dipoles. The same technique also allows for the measurements of the z component of the flexoelectric polarization using a pyroelectric response of a hybrid (homeoplanar) aligned nematic cell and proper subtracting of the surface contributions. The flexoelectric polarization has been shown to be opposite to the sum of the surface terms mh + mp and directed from the planar to homeotropic interface. This means that the sum of the flexoelectric coefficients e=(e1 + e3) is positive (e ≅ 1.7 pC/m at 28℃). The temperature dependence of e has been shown to involve a combination of both the quadrupolar and dipolar contributions
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
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