Physics
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Item Factors Influencing Patient Dose in Diagnostic Radiography.(SET, 2008) OLARINOYE, OYELEKE; Igwe, KItem Optical and microstructural properties of neutron irradiated RF- sputtered amorphous alumina thin films(2017) OLARINOYE, OYELEKE; F.O. OGUNDAREItem PHOTON BUILDUP FACTORS FOR SOME TISSUES AND PHANTOM MATERIALS FOR PENETRATION DEPTHS UP TO 100 MFP(2017) OLARINOYE, OYELEKEThe use of photons in diagnostic and therapeutic medicine requires the accurate determination of photon Irradiation dose in human tissues. Photon buildup factors represent corrections to photon interaction when the Beer-Lambert conditions are not met. Equivalent atomic numbers, energy absorption and exposure buildup factors of 10 human tissues (adipose tissue, blood, collar bone, brain, breast, eye lens, lungs, ovary, testis and skeletal muscles) and 4 equivalent materials (water, nylon, mylar and polyvinylchloride) were evaluated using the geometric progression (G-P) fitting method. The buildup factors were evaluated for 25 standard photon energies (0.015-15 MeV) and for penetration depth up 100 mfp (mean free path). The magnitudes equivalent atomic numbers and buildup factors for the studied materials varied in similar pattern with energy and penetration depth. The variations in the equivalent atomic number and the buildup factors with photon energy were attributed to elemental compositions of the individual tissue/ equivalent material and the dominance of different photon interaction in the energy spectrum considered. The behaviour of the equivalent atomic number for the equivalent materials suggests that each of them can be used to represent different human tissues for phantom construction and dose evaluation.Item Crystal structure refinement of co-doped Ba0.88Ca0.12Ti0.975Sn0.025O3 ceramic(2017) Umaru Ahmadu; OLARINOYE, OYELEKE; Moses Agida; Auwal M. MuhammadBa/Ca-doped barium titanate has been prepared by solid state reaction to produce Ba0.88Ca0.12 Ti0.975Sn0.025O3(BCST) ceramics. Five samples were irradiated using neutron fluence of 8.1 106, 9.72 107, 8.75 108, 6.99 109 and 1.4 1010 n/cm2 (BCST-06 to-10). The structure and phase compositions of the control (BCST) and irradiated samples were determined by X-ray diffraction and indicate the presence of a majorly single phase tetragonal barium titanate (S.G.P4mm) with a minor phase CaTiO3 (orthorhombic). However, Rietveld refinement using GSAS II suite of programs indicates a tetragonality ratio (c/a ¼ 0.996) which is pseudocubic with a reduction in volume of 0.03% in the control compared to pristine BT. The irradiated samples exhibited changes in tetragonality (maximum of 0.82%) and variation in volume (0.58%, maximum) over the range of fluence investigated. A complete vacancy was observed in the Ca site of BCST10 but not in the oxygen sites while the occupancies of other metal sites varied. The substitution of Sn is expected to lead to a lower transition temperature and an increase in dielectric constant near the transition temperature of the control. While the changes in volume, tetragonality and occupancy of the irradiated samples are expected to affect their electromechanical properties due to changes in the Ti octahedra which would lead to a slight degradation in device performance.Item He+ induced changes in the surface structure and optical properties of RF-sputtered amorphous alumina thin films(ELSEVIER, 2016) F.O. OGUNDARE; OLARINOYE, OYELEKEHigh quality 50 nmthickstoichiometric amorphous aluminium oxide films were reactively sputtered on micro scope glass slide substrates. The films were exposed to energetic (2.20 MeV) He+ at different ion fluences of 6×1012 ion/cm2;1×1013 ion/cm2;2×1013 ion/cm2;3×1013 ion/cm2; and 4 × 1013 ion/cm2. The effect of the ion irradiation on the optical, structural phase and surface properties of the alumina films was investigated via UV–VIS–NIRspectroscopy,X-raydiffraction analysis and theatomicforcemicroscopyrespectively. Thetrans missionandabsorptionspectraoftheirradiatedfilmsshowedvariationthatdependedonionfluence.Therefrac tive index, extinction coefficient, optical conductivity, dielectric constant and energy loss functions of the films were also affected by He+ irradiation. Optical band gap and films' structural phase were however not altered bytheionirradiation. The variation in optical constants induced by radiation was attributed to electronic excita tion and increase in surface roughness of the filmsItem ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIATION HAZARDS IN THE TERTIARY INSTITUTIONS IN MINNA, NIGER STATE, NIGERIA.(2012) Kolo, M. T.,; Baba-Kutigi, A. N.,; OLARINOYE, OYELEKE; Sharifat, I.Item Measurement of Background Gamma Radiation Levels at Two Tertiary Institutions in Minna, Nigeria(2010-03-14) OLARINOYE, OYELEKE; SHARIFAT, I.; BABA-KUTIGI, A, N.; *KOLO, M.T.; **ALADENIYI, K; BABA-KUTIGI, A, N.;; KOLO, M.T.; ALADENIYI, KAn in-situ measurement of the background radiation level was carried out at the vicinity of three campuses of two major tertiary institutions in Minna. A portable Geiger-Mueller tube-based environmental radiation dosimeter was used for the measurement. A total of 34 point was surveyed across the three institutions for background environmental radiation. The dose rate range obtained are: at the Niger State College of Education Minna (NCM), the dose rate varies from 0.125 µSv/hr to 0.171µSv/hr; at the Federal University of Technology Bosso Campus (FUTB) it wass between 0.152 µSv/hr and 0.184 µSv/hr; and at the Federal University of Technology Gidan Kwano campus FUTG it was between 0.137 µSv/hr and 0.184 µSv/hr. In all the 34 points surveyed the mean dose rate was 0.154 µSv/hr with a standard deviation of 0.017 µSv/hr. Generally, the dose rate level in each of the institutions surveyed are comparable to one another and could simply be attributed to natural sources. The Average annual effective dose obtained from this study is 0.189 mSv/annum which is still less than the recommended limit of 1mSv/annum by International Commission on Radiation Protection [ICRP] for non occupational population exposure.