We consider the phenomenology of cosmic-rays (CRs) and stress the interest of jointly studying their properties over the whole energy spectrum. While UHECRs are known to raise important physical and astrophysical problems, we recall that low-energy CRs also remain poorly understood, and we indicate the possibly important role of superbubbles in accelerating CRs up to a few EeV. We also investig...

We discuss a scenario in which the highest energy cosmic rays (CR's) and cosmological-ray bursts (GRB's) have a common origin. This scenario is consistent with the observed CR ux above 10 20 eV, provided that each burst produces similar energies in-rays and in CR's above 10 20 eV. Protons may be accelerated by Fermi's mechanism to energies 10 20 eV in a dissipative, ultra-relativistic wind, wit...

The interaction of thermal radiation with conduction and laminar natural convection in a vertical circular pin, situated at participating gas, is numerically investigated. An absorbing and emitting gas is considered, and treated to be a gray participating media. Under the idealizing of gray gas, the Rosselan4 approximation is employed to describe the radiative heat flux in the energy equation. ...

results the results showed that the epoxy plates 6 and 2 mm thick had the highest and the lowest averages of shielding effectiveness at 4.48 db and 1.90 db, respectively. however, increasing the thickness was useful up to 4 mm. in addition, in a similar attenuation pattern, x-band frequency was divided into lower, middle, and upper sections. the lower section had the highest shielding effective...

In this work, we use Drude-Lorents model description to study the radiation of a charged particles moving in a homogeneous dispersive medium. A suitable quantized electromagnetic field for such medium is utilized to obtain proper equations for energy loss of the particle per unit length. The energy loss is separately calculated for transverse and longitudinal components of the filed operators. ...

Background: This study investigated the γ-rays shielding properties of some building materials in Sudan has been investigated. Materials and Methods: Photons attenuation coefficients and half value layer (HVL) were experimented using Cs-137 and Co-60 sources.  The measurements were performed to gauge the intensity of radiation when performed unshielded, the specific thickness of selected sample...

Neutrino radiation is expected to impose major design and siting constraints on many-TeV muon colliders. Previous predictions for radiation doses at TeV energy scales are briefly reviewed and then modified for extension to the many-TeV energy regime. The energy-cubed dependence of lower energy colliders is found to soften to an increase of slightly less than quadratic when averaged over the pla...

The solar radiation in the form of electromagnetic waves emitted by the sun, travels the extraterrestrial space without any essential interaction with matter, and reaches the earth’s atmosphere. Therein, the beam solar radiation undergoes physic-chemical processes and experiences scattering by (macro) molecules, dust, or other tiny particles in the air. This process creates the solar radiation ...

We study the full history of the universe in the presence of inflaton, matter, radiation, and holographic dark energy. The time evolution of the scale factor is obtained by solving the Friedmann equation of the universe without artificial ansatz. We discuss that the second law of thermodynamics dictates the accelerating expansion of the dark energy dominant phase to the universe. In addition, w...