Cilt:02 Sayı:02 (2015)
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Item Influences of irradiation on the C–V and G/ ω –V characteristics of Si3N4 MIS capacitorsKAYA, Ş.; YILMAZ, E. ; ÇETİNKAYA, A.O.The effects of gamma-ray exposures on the electrical characteristics of Silicon Nitride (Si3N4) metal–insulator– semiconductor (MIS) structures have been investigated at room temperature. The MIS structures were irradiated with the GAMMACELL 220 Co-60 radioactive source. The distributions of interface states and series resistance were determined from the C–V and G/ω-V characteristics by taking into account the irradiation-dependent the barrier height. Both the values of series resistance, interface states and barrier heights enhanced with increasing dose. Experimental results demonstrate that gamma-ray irradiations have the significant effects on electrical characteristics of Si3N4 MIS structures.Item Kinetic analysis of the main glow peak of α-Al2O3:C exposed to high irradiation doseNYIRENDA, A.N.; CHITHAMBO, M.L.This paper reports kinetic analysis of the main thermoluminescent peak in α-Al2O3:C for irradiation doses as high as 120 Gy and at various heating rates going as low as 0.01 K/s. The dependence of the various methods of kinetic analysis on irradiation dose and/or heating rate has been assessed with respect to the main peak. The dose response of the peak to high beta irradiation has also been presented.Item Present state of the art of a fast neutron dosimeter incorporating RPL detectorsSALEM, Y.O.; NOURREDDİNE, A.; NACHAB, A.; ROY, C.; PAPE, A.The recently introduced radiophotoluminescent (RPL) detectors offer a unique combination of advantages for radiation monitoring that include rapid exploitation, stability to fading, reusability, and insensitivity to light, temperature and humidity. We look at the behavior of an RPL-based fast neutron dosimeter capable of measuring neutrons in an n- field. The tested dosimeter consists of an ordered assembly of Al foil, RPL detector (I), Al foil, polyethylene converter, RPL detector (II) and Al foil encased in a polyethylene container. The difference between the two RPL configurations represents the (n,p) protons and is related to the fast neutron dose. The dosimeter response is linear and shows an acceptable angular dependence. However the measured detection threshold for this dosimeter is too high for routine monitoring. This threshold could be lowered at to a more practicable value if next generation improvements in RPL detectors and the reader are applied. The main shortcomings we encountered are (i) a 1.7 µm thick dead layer at the front surface of the detectors that render them insensitive to a large fraction of the recoil protons and (ii) an intrinsic detector background that could be reduced if the reader were able to separate individual densely ionized zones created by the recoil protons from the -ray signal.Item Analytical Formulae to Calculate the Total Efficiency of an Arbitrarily Positioned Point Source by an Elliptical Cylindrical DetectorABBAS, M. I.; HAMMOUD, S.; IBRAHIM, T.; SAKR, M.In this paper, a direct analytical method is presented for calculating the absolute efficiency of an elliptical cylindrical detector in the case of an arbitrarily positioned (above the major axis a) point source. The absolute efficiency is required to determine the activity of an unknown radioactive source, taking into account the attenuation of the gamma-ray photons. The validity of the derived analytical expressions was successfully confirmed by the comparison with some published data.Item Synthesis and characterization of new phosphor based MTiO3KAYACI, N.; DAYAN, S.; KÜÇÜK, A. K.; KALAYCIOĞLU ÖZPOZAN, N.; ÖZTÜRK, E.; KARACAOĞLU, E.In this study, new titanate phosphors were synthesized. The Dy3+, Eu3+, Ho3+ rare-earth ions were used as dopants to CaTiO3, SrTiO3, and BaTiO3 host crystals. The optimization of reaction conditions were carried out by thermogravimetry (TG) and differential thermal analysis (DTA) methods. The mixtures to achieve a solid state reaction were heated in porcelain crucibles for preheating process at 600 oC and 800 oC and final heating process at 1000 oC for 16 hours in the open atmosphere. The reaction products were characterized by X-ray powder diffractions (XRD). Surface investigations and elemental analysis were determined by using SEM-EDX instrument. Photoluminescence spectrophotometer (PL) was used for the observation of the excitation and emission spectra.