Extracting dielectric fixed charge density on highly doped crystalline-silicon surfaces using photoconductance measurements

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By-Pass Cement Dust, as an industrial cement waste, was used to prepare some gamma-ray shielding glasses aiming to protect people and environment from hazard radiations, some phosphate glasses containing different amounts of by-pass cement dust have been prepared by the melt quenching method. The selected molecular composition was [(100-x) % P2O5 -(x) % By-Pass Cement Dust (where x=30,35,…,60)] in steps of five. The obtained experimental density and molar volume values were inspected and were then compared with those obtained empirically for the close packed structure of the corresponding compounds. These comparisons evidenced the short-range order and randomness character of the studied samples. From the IR analysis, different phosphate speeches appeared in the glass networks, as well as some silicate groups appeared in the spectra of all samples due to the presence of considerable amount of SiO2 in by-puss cement dust. Also, the present CaO act to increase Q 2 and Q 1 species as well as to increase the non-bridge oxygen, The tetrahedral are classified using the Q i terminology .where i represent the number of bridging oxygen's per tetrahedron It appeared also that, as by-pass cement dust was increased, the intensities of O-H and H-O-H groups decreased which indicated that CaO (the major constituent of by-pass cement dust) decreases the absorption of water and strengthening the studied samples. The suitability of such glasses to act as gamma-ray shielding materials was also examined and a correlation between the chemical composition (By-Pass Cement Dust content) and gamma-ray attenuation behavior was established.

The need for low cost, compact, high-power laser systems with their applications in medicine and high energy physics is growing rapidly. Counter propagating laser pulses amplification promise a breakthrough by the use of much smaller amplifying media, that is, millimeter plasma scale. The full-wave solution for the two laser pulses interact in almost homogenous or plasma channel is conducted along with particle-in-cell simulation for the same pulses' parameters. Motivated by the promise of reduced cost and complexity of the intense lasers, the amplitudes of laser pulses are taken to be small (a0 < 1). The growth rate of the seed pulse and the dephasing limitations are calculated. The results show that the energy is transferred from the pump pulse to the seed pulse effectively depending on the length of amplification and the isolation of the limiting conditions. A wide variety of system parameters such as frequency of laser pulses, plasma density matched to three waves interaction, and intensity of the pump wave and seed wave are studied. The influence of plasma and pulses parameters on simulation results are thoroughly investigated using a moving window technique and are compared with theoretical and numerical predictions. The comparison shows that the numerical full wave solution is very sensitive to any plasma density changes near the entrance of the pump pulse into the plasma.