Departments of Physics

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Start date: 2024Has files: Yes

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    QUANTITATIVE ANALYSIS OF ETHANOL CONTENT AND KEROSENE ADULTERATION OF MOTOR GASOLINE IN ETHIOPIA, USING FOURIER TRANSFORM INFRARED SPECTROSCOP
    (HAWASSA UNIVERSITY, 2024-06) YORDANOS FEKEDE
    The automotive sector in Ethiopia is a major player of economic growth and most activities rely on it. Gasoline is the most often utilized energy source used to power automotives with internal combustion engine; as a result its demand is growing from time to time. Due to the high demand, its quality is usually compromised. Among others, ethanol and kerosene are the most commonly added substances due to their cheaper price, and surplus availability compared to gasoline. According to ISO only 10% Ethanol should be added to gasoline to reduce greenhouse gas emission. However, in many countries including Ethiopia, there is no strict control on the amount of ethanol and the presence of kerosene in gasoline. Some random investigations showed that there are illegal adulteration practices on most gasoline stations [40]. Detecting adulterants and determining ethanol content can’t be done by visual inspections due to their similarity and miscibility with the actual gasoline acquiring analytical techniques. This study aims to quantify ethanol content and kerosene adulteration in five gasoline brands from gas stations located in Hawassa city, Ethiopia using FT-IR spectroscopy. The ethanol content is determined by using the absorption peaks aroused from O-H and C-H stretching vibrations and the kerosene adulterations detected using absorption peaks in 1378 and 1460 region of IR spectrum. The later peaks are believed to be originated from the CH3 bending vibration. The results obtained by FT-IR technique showed that there is an ethanol blending practice exceeding the limit set by ISO ranging from 2% to 9% and significant kerosene adulteration has also be detected. The results suggest that there are significant kerosene adulteration and ethanol blending noncompliance with gasoline quality standards in gasoline supply chain.
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    STUDIES OF STRUCTURAL AND OPTICAL PROPERTIES OF LEAD SULFIDE THIN FILM AT DIFFERENT DEPOSITION TIME PREPARED BY CBD TECHINIQUE
    (HAWASSA UNIVERSITY, 2024-09) YIRGALEM FIKIRE ALEKER
    In this study, PbS thin films were deposited on glass substrates using the chemical bath deposition (CBD) technique. Lead acetate, thiourea, and sodium hydroxide were used as precursors for the Pb²⁺, S²⁻ source, and complexing agent, respectively. The deposition was carried out at a bath temperature of 80°C for varying durations of 20, 25, 30, 35, and 40 minutes. Following deposition, the films were annealed at 200°C for 90 minutes. The structural and optical properties of the films were characterized using X-ray diffraction (XRD) and UV-Visible spectroscopy. XRD analysis revealed that the as-deposited PbS films exhibited a nanocrystalline cubic (galena) structure with a face-centered cubic lattice, showing diffraction peaks corresponding to the (111), (200), (220), (222), (311), (400), (420), (331), and (422) planes, with a preferred orientation along the (200) plane. The crystallite size was estimated to increase from 33.27 nm to 37.50 nm as the deposition time increased. Additionally, both dislocation density and lattice strain decreased with increasing deposition time. Optical absorption measurements revealed strong absorption in the wavelength range of 500 nm to 750 nm. The optical band gap was reduced from 1.62 eV to 1.51 eV as the deposition time increased from 20 to 40 minutes in 5-minute intervals
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    ATOMIC ABSORPTION SPECTROSCOPIC ANALYSIS OF HEAVY METAL CONTENTS OF MALT BEVERAGES CONSUMED IN ETHIOPIA
    (HAWASSA UNIVERSITY, 2024-06) MARISHET TESSEMA TAMIRU
    This study was designed to detect the levels of some heavy metals such as, nickel, cobalt, chromium, lead, and copper in five different brands of malt beverages commonly consumed in Ethiopia (Sinq, Sofi, Nigus, Malta Guinness and Bertat), using flame atomic absorption spectrometry (FAAS). The heavy metal contents obtained using FAAS shows slight differences among the five malt beverages. Generally in all brands of malt beverages, the concentration of Cu is the highest and Ni has the lowest concentrations. The order of abundance of these heavy metals is: Cu > Co > Cr > Ni. The levels of Ni and Cr show very small variations among the different brands of malt beverages. On the other hand, concentrations determined for Cu, Co shows slightly higher variations among the different brands. The level of Cobalt (Co) concentrations are in the range between 0.048 mg/L and 0.073 mg/L, which is above the maximum limit that has set by WHO (0.01 mg/L) in five malt beverages. The Ni level obtained in the beverages range between 0.015 mg/L and 0.029 mg/L, which is above the maximum limit set by WHO (0.02 mg/L) except the Bertat that has concentration range 0.015mg/L. The concentration of Cu is in the range from 0.4 mg/L to 0.68 mg/L, while the maximum allowed value set by WHO has 2.0. Therefore the levels of Cu in all the samples are within the acceptable limit. The level of Cr in the samples range between 0.032 and 0.047 which is again below the maximum allowed limit set by WHO (0.05 mg/L). In all samples, the level of Pb is below the detection limit of the instrument. In general, few malt drinks, the level of some heavy metals are slightly above the maximum limit set by the national and international organizations. Therefore, I suggested that malt beverage producing companies should pay attention to continuous monitoring of the sources of these heavy metals in malt beverages. The experimental results are validated in terms of accuracy, precession, linearity and method of detection limit. The accuracy was determined by spiking experiment and an accepted percentage recovery was obtained in the range of 97%-98%.
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    A Study of Incomplete Fusion Reaction and its Correlation with Projectile Energy and Entrance channel Mass-Asymmetry in some 12C/16O-Induced Reactions at ≈3–9 MeV/nucleon
    (HAWASSA UNIVERSITY, 2024-05) Mustefa Kedir Dubiso
    In this work, the effects of projectile energy and entrance channel mass-asymmetry on incomplete fusion reaction in 12C + 128Te, 12C + 141Pr, 12C + 159Tb, 16O + 130Te, 16O + 159Tb and 16O + 181Ta, projectiles + targets systems at ≈ 3-9 MeV/nucleon were studied. Cross sections of various reaction products populated via complete and incomplete fusion of 12C projectile with 128Te, 141Pr and 159Tb-targets and 16O projectile with 130Te, 159Tb and 181Ta targets were calculated using the reaction model code PACE4. The predicted cross sections were compared with experimentally measured data from EXFOR database. For a representative non α-emitting ( 12C, 4n) channel from a representative in 12C + 159Tb system, experimentally measured cross sections agreed with PACE4 prediction for level density parameters K=10. For the same level density parameters a representative α-emitting (12C, α3n) from a representative in 12C + 128Te projectile + target system, the experimentally measured cross sections are higher than the PACE4 predicted. The observed difference is attributed to the contribution of incomplete fusion following the prompt break-up of the projectiles into α-clusters. An attempt was made to deduce the contribution of incomplete fusion reactions from presently investigated projectile and target systems. It was found that the incomplete fusion fraction, in general, increases with the increase in projectile energy. Furthermore, the result indicated that at the same normalized relative velocity, the incomplete fusion fraction is higher for mass-asymmetric projectiles and targets systems
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    EFFECT OF CADMIUM ION CONCENTRATION ON THESTRUCTURALAND OPTICAL PROPRTIES OF CdS THIN FILMS BYCHEMICALBATHDEPOSITION METHOD
    (HAWASSA UNIVERSITY, 2024-11) TESFALEM BEREHANU AYELE
    Cadmium Sulfide (CdS) thin films were successfully deposited on glass substrates at four different concentration of cadmium ion (Cd 2+ ) by chemical bath deposition technique at a bath temperatureof80 0c for 50 minutes. The reagents used for the deposition were cadmium sulphate (CdSO4) for Cd2+source, thiourea (CS(NH2)2) for S 2- source and ammonia (NH3) as complexing agent. Thesynthesized thin films were characterized by XRD and UV-Vis Spectrophotometer. TheXRDanalysis of CdS thin films revealed that cubic crystal structure with preferred orientationalongthe(111) plane and the crystalline size increases in the range of 8.78nm to 18.98nmwith increasingcadmium ion (Cd 2+ ) concentration in the solution. Moreover, after the increase of Cd2+ionconcentration one peak of CdO with cubic structure appeared. Also the dislocation density(δ) andstrain (ε) were calculated. From VU-Vis Spectrophotometer study, the optical band gap valuesofCdS thin films decreased in the range of 2.0eV to 1.85eV with increasing the cadmiumion(Cd2+)concentration.
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    A Thesis Submitted to School of Graduate Studies College of Natural and Computational Science in Partial Fulfillment of the Requirements for the Degree of Master of Science in Physics.
    (HAWASSA UNIVERSITY, 2024-05) Tekalegn Mitiku
    This work studied the production cross section and yield of medically important radionuclides, such as 68Ga and 64Cu, generated during irradiation of 66Zn-target with α-projectile at ≈ 10-40 v MeV. The experimental cross-sections taken from the EXFOR database were compared with the theoretical model calculations using nuclear reaction model codes COMPLETE, TALYS1.95 (G), and EMPIRE3.2. A good agreement was achieved for the measured data and calculated production cross-section using the TALYS1.95 (G) code. The 68Ga and 64Cu yields were computed using TALYS1.95 (G) predicted cross-section data. Also, the possible isotopic impurities were identified, and their contributions were estimated. Based on the yield calculations, the production yield of 68Ga was found to be 39.6 GBq/μAh, at 28 MeV without any significant contribution from its isotopic impurities 67Ga and 66Ga; in addition a yield value of 85.9 MBq/μAh at 40 MeV was obtained for medically important 64Cu radionuclide with negligible isotopic impurities contributions from 66Cu and 62Cu radionuclides
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    ICP-OES ANALYSIS OF SELECTED HEAVY AND TRACE ELEMENTS IN DRINKING TAP AND SPRING WATER IN DURAME TOWN AND THE SURROUNDING AREAS
    (HAWASSA UNIVERSITY, 2024-11) TAREKEGN TEKLE ERGENO
    This thesis presents an analysis of the concentrations of heavy metals and trace elements in drinking water from tap and spring sources in Durame city, Southern Ethiopia, using Inductive Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Water contamination by metals such as lead (Pb), cadmium (Cd), and iron (Fe) poses significant health risks, making it crucial to monitor these elements. Water samples from four sites were analyzed for physical parameters such as pH and electrical conductivity (EC), alongside concentrations of metals like arsenic (As), zinc (Zn), copper (Cu), chromium (Cr), and manganese (Mn). The results were compared with the World Health Organization (WHO) drinking water standards to assess potential health risks. The study found that while most metals, including Cu, Zn, and Cr, remained within permissible limits, levels of Cd, Pb, and Fe in some samples exceeded WHO guidelines. The high levels of these metals indicate potential contamination from industrial or agricultural activities in the area. Recommendations include implementing proper water treatment processes, strengthening local environmental regulations, and conducting regular water quality monitoring to ensure public health safety. This research provides important insights into the quality of drinking water in Durame and serves as a baseline for future studies on water safety and heavy metal contamination in the region.The results are validated in terms of precession, linearity and limit of detection.
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    THE EFFECT OF DEPOSITION TEMPRATURE ON THE CADMIUM DOPED COPPER OXIDE THIN FILMS DEPOSITED BY CHEMICAL BATH DEPOSITION METHOD
    (HAWASSA UNIVERSITY, 2024-11) SIMACHEW SHITAHUN
    The cadmium doped copper oxide thin films were deposited on the glass substrate for 30minutes by using chemical bath deposition. The bath contained the solution of cadmium chloride and copper acetate as a source of cadmium and copper ion respectively. Hydrazine and ammonia used as complexing agent at deposited temperature of 40ᵒC, 60ᵒC, 70ᵒC and 80ᵒC. The films were characteri zed using XRD and UV- VIS characterization techniques. According to X-ray diffraction analysis the prepared thin films revealed that monoclinic CuO and cubic Cu2O phases coexist in all samples. Th ere also was very weak peak of cubic face centered CdO only at lower deposition temperature 400C; however it was inhibited at deposition temperature 600C, 700C and 800C. The crystallinity of Cu2O and CuO phases were increased as deposition temperature increased except a slight decreased from 600C to 700C for Cu2O and from 70°C to 80°C for CuO. However, dislocation and lattice strain decr eased with increasing temperature, except a slight increased from 600C to 700C for Cu2O and from 7 0°C to 80°C for CuO. The optical study of the films showed that absorbance was higher at shortest wave length.The band gaps of the films were decreased from 1.95 eV to 1.90 eV for deposition temp erature increased from 400C - 800C
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    Studying The Effect Of Metallic Precursor Concentration On The Structural And Optical Properties Of Zinc sulfide Thin Films Synthesized By Chemical Bath Deposition Method
    (2024-05) Olchitu Bekele
    Zinc sulfide (ZnS) thin films with different concentrations of zinc chloride (0.3M, 0.5M, 0.7, 0.9M and 1.1M) have been deposited on a glass substrate made by chemical bath deposition technique in basic medium. Zinc chloride, thiourea, ammonia, and hydrazine hydrate were used to synthesize ZnS thin films. The films were annealed at 200°c. This study investigates how the concentration of metallic precursor affect the crystal structure and optical properties of Zinc sulfide thin films. The XRD result shows that no sharp peak which indicates the samples is amorphous nature. UV-Vis spectroscopy was used to analyze the optical characteristics of the deposited thin films. The absorbance increase with increasing of the zinc sulfide concentration and the band gap energy for the films prepared in different concentration of zinc chloride decrease from 3.53 to 3.42 eV with increasing of zinc sulfide concentrations. The results demonstrated that concentration of metallic precursor have distinct effects on optical absorbance and band gap energy.
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    A Thesis Submitted to School of Graduate Studies College of Natural and Computational Science in Partial Fulfillment of the Requirements for the Degree of Master of Science in Physics.
    (2024-05) Negash Gimbo
    In this work, theoretical predicted production cross section were made using COMPLETE, EMPIRE-3.2 and TALYS-1.95(G) reaction model codes for the production of medically important 88Y, 89Zr, 90Y and 99Mo radionuclides in the interaction of α-projectile with 89Y and 96Zr-targets at ≈10-60 MeV. The theoretical predicted production cross sections were compared with the experimental data available in the EXFORE database. The TALYS-1.95(G) code predicted production cross sections of medically important 88Y, 90Y, and 89Zr radionuclide, in general, are found to be in good agreement with experimental measured production cross sections over the entire energy range except for 99Mo radionuclide. Pearson‟s statistical coefficients confirmed a strong positive correlation between TALYS-1.95(G) codes predicted and experimentally measured production cross section except for 99Mo. Furthermore, it was found that the TALYS-1.95(G) predicted and experimentally measured production cross-sections in general attained maximum values below ≈45MeV α-energy for medically important 88Y, 90Y, and 89Zr radionuclides via complex (α,x) channel. Thus the obtained result can be used as reference cross-section data for optimized production of medically important 88Y, 90Y, 89Zr and 99Mo radionuclides using single α + 89Y, 96Zr system.