Browsing by Author "Anteneh Getachew"

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    Evaluation of Reaction Cross-Section for Deuteron Induced Radioisotope [125I,62ZN,15o and 103PD] at Different Energy Ranges Using the PACE 4 CODE
    (Addis Ababa University, 2024-06) Anteneh Getachew; Tilahun Tesfaye
    This thesis work emphasize on theoretical evaluating reaction cross sections of deuteron induced nuclear reactions for the production of therapeutic radionuclide using PACE4 statistical model code , which is a code based on the statistical model of nuclear reactions. PACE4 statistical model code is used to calculate the theoretical nuclear cross section in the production processes of 125I, 62Zn, 15O and 103Pd, while experimentally decoded nuclear cross sections data of these radionuclide were taken from ENDF(Evaluated nuclear data file) IAEA database, to compute a reliable result, PACE4 statistical model code performed at level density parameter(K=8, K=10 and K=12 ) and the number of cascades(events in monte carlo calculation) is set at 100,000. The target radioisotopes are 124T, 63Cu, 14N and 103Rh are taken for the production of medical useful radioisotope 125I, 62Zn, 15O and 103Pd respectively. Deuteron energies ranging from 4.5MeV to 20MeV were considered for the production of 125I, 17MeV to 35MeV for the production of 62Zn, 1MeV to 20MeV for the production of 15O and energy range from 6.5MeV to 23.5MeV were considered for the production of 103Pd, and then experimental and theoretical outputs of nuclear cross sections of these radionuclide production were analyzed and compared. The maximum experimental and theoretical nuclear cross section computed at different energy range is stated below respectively: for 124T (d,n)125I reaction the maximum cross section at deuteron incident energy of 9.0MeV was 232 mb and 555 mb at 9.5MeV ( at K=12), for 63Cu(d,3n)62Zn reaction 50.5 mb at 33MeV and 63.9 mb at 31.5MeV ( at K=8), for the reaction 14N(d,n)15O the maximum cross section was 213 mb at 3.5MeV and 214 mb at 12.5MeV ( at K=12) and for the reaction 103Rh(d,2n)103Pd the maximum cross section was 1056 mb at 13.5MeV and 1390 mb at 18.5MeV ( at K=12). The PACE4 code slightly gives good agreement with ENDF determined excitation function at some computed radionuclide production considered under this study,while the rest results are unfitted with the ENDF data. It has been observed that complete fusion, incomplete fusion and pre-equilibrium emission processes play important roles in heavy ion reactions at these energies. The observed disagreement may be credited to the contribution from the incomplete fusion reaction, pre-equilibrium emission processes and light particle reaction is not well taken into account by PACE4 statistical model code.
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    Segmental and Non-Segmental Phonology of Kūnámá ̄
    (Addis Ababa University, 2018-06) Anteneh Getachew ; Moges Yigezu
    This dissertation presents the descriptions of the segmental and non-segmental phonology of Kunama, a Nilo-Saharan dialect cluster spoken in Western Eritrea and Northern Ethiopia. It also provides an annotated multimedia corpus of the names and description of the Kunama cultural artifacts. The study uses primary data recorded from speakers of the Kunama Shukre dialect, spoken by an isolated minority group living in Tahtay Addi Yabo Woreda of Northwestern Zone of the Tigray Regional State, Ethiopia. The data was collected in three-round fieldworks in a period of two years (2014-15). The study has applied both impressionistic and instrumental analyses methods. The segmental phonology part covers the description of consonant and vowel sounds, phonotactics and syllable structure, phonological and morphophonological process and phonological adaptation of loanwords. Kunama (Shukre) has 18 consonant phonemes, whereas, the glottal fricative /h/ consonant, which has previously been proposed as the 19th consonant phoneme of Kunama, is found to be marginal. Two labialized velar consonants are attested to be the allophonic variants of the basic velar phonemes. The language has five phonemic vowels with an equal number of longer counterparts. The schwa and the central high-close vowel have a phonetic status despite that they are frequent. The analysis of phonotactics and syllable structure shows that the language has a richer and moderately complex inventory of syllable shapes. The productive and the most frequent consonant clusters (CC) follow sonorant-obstruent pattern, in which the prenasalized sequences (Nasal-Obstruent) are the commonest of all. Clusters and geminates occur only word-medially, so more than one consonant is severely marked, word-initially while three consonant sequences (CCC) are disallowed. Typologically, Kunama syllables are specified as light-open, heavy-open, light-closed and heavy-closed structures. Syllable weight specification is based on the mora count in the rhyme constituents of a syllable. Kunama light syllables are mono-moraic, i.e. having either a short vowel or a short vowel with a non-sonorant coda; whereas, the heavy syllables are bi-moraic having a long vowel, a diphthong, or a short vowel with a sonorant coda. A (C) V (C) template that makes an obligatory nucleus and optional margins, therefore, represents the Kunama basic syllable structures. While CV syllable is the unmarked structure, closed syllables (VC and CVC) are constrained word-finally. The morphophonemic processes comprise of terminal vowel deletion, vowel and glide epenthesis, glide formation, vowel rounding assimilation, gemination and degemination. Post-lexical alterations may cause constraint violations and necessitate resyllabification as such some constraints that operate on non-derived lexical items may not diametrically encode onto derivations. The analysis of phonological adaptation of loanwords explores the adjustment of word shapes and the mapping of sound segments of borrowed terms. Accordingly, consonant final loanwords are adapted with epenthesis of the nominal vowel suffix [a], and sound segments are adapted via substitution, deletion and retention strategies. The vowel adaptation is asymmetrical as both phonetically and phonologically grounded changes have been observed; nonetheless, the consonant adaptation is phonologically grounded. The non-segmental phonology part covers the analyses of gemination, vowel length and tone, in the lexicon and in the grammar. Kunama is a tone language with quantity contrast of vowel and consonant length. It has three phonemic tone levels (High, Mid and Low) that combine in nine ways on the surface of bi-moraic syllables and on sequences of two light syllables. These level combinations are claimed to be the basic melodies of the language. Complex (polysyllabic) contour melodies that combine simple rises and falls are attested on polysyllabic words. The study attempts to show the importance of pitch scaling in Kunama tone production as such it proposes a four-point pitch height scale in the tonal space of three distinctive level heights. The F0 scaling splits the high tone into extra-high and high pitches though no evidence shows the prominence of the former in underlying contrast. Tone plays a grammatical role as well, and it marks number of the possessor, in a range of possessive constructions, and number of person object in verbs. It also identifies inclusive vs. exclusive possessor, copula vs. genitive, and used as an intensifier morpheme on adjectives in attributive function. The salient tonal processes in Kunama are triggered by morpheme boundary phenomena. These include spreading and floating of tones, re-linking of floating tones, high tone shifting and docking, contour formation, tone assimilation and a low tone terrace.