Mustafa Karadag

Measurement of thermal neutron cross-sections and resonance integrals for and by using –Be isotopic neutron source

Abstract Thermal neutron cross-sections and resonance integrals for the 71 Ga ( n , γ ) 72 Ga and 75 As ( n , γ ) 76 As reactions were measured by the activation method. The experimental samples with and without a cylindrical Cd shield case in 1 mm wall thickness were irradiated in an isotropic neutron field of the 241 Am –Be neutron source. The induced activities in the samples were measured by high-resolution γ-ray spectrometry with a calibrated reverse-electrode germanium detector. Thermal neutron cross-sections for 2200 m/s neutrons and resonance integrals for the 71 Ga ( n , γ ) 72 Ga and 75 As ( n , γ ) 76 As reactions have been obtained relative to the reference values, σ 0 =13.3±0.1 b and I 0 =14.0±0.3 b for the 55 Mn ( n , γ ) 56 Mn reaction as a single comparator. The necessary correction factors for gamma attenuation, thermal neutron and resonance neutron self-shielding effects were taken into account in the determinations. By defining Cd cut-off energy 0.55 eV , the results obtained were: σ 0 =4.41±0.18 b and I 0 =32.3±2.3 b for 71 Ga ( n , γ ) 72 Ga , and σ 0 =4.15±0.24 b and I 0 =63.5±3.8 b for 75 As ( n , γ ) 76 As . These results are discussed and compared with previous measurements and the evaluated data in ENDF/B-VI and JENDL-3.2. Thermal neutron cross-sections for 71 Ga ( n , γ ) 72 Ga and 75 As ( n , γ ) 76 As reactions are in good agreement with the recent measurements. However, the discrepancies between present results and some of old experimental data for resonance integrals for both reactions are within about 8–58%.

Determination of the demographic characteristics of science and technology teachers: Sample of Istanbul

Bu calismada, ilkogretim Fen ve Teknoloji Ogretmenlerinin demografik ozelliklerinin ortaya cikarilmasi amaclanmistir. Arastirmada tarama modeli ve tesadufi ornekleme yontemi kullanilmistir. Arastirmanin orneklem grubunu, Istanbul’da calisan 204 Fen ve Teknoloji ogretmeni olusturmustur. Verilerin toplanmasinda Kisisel Bilgi Formu kullanilmistir. Sonuc olarak, Istanbul’da calisan Fen ve Teknoloji ogretmenlerinin demografik ozellikleri ortaya cikarilmistir. Arastirma sonucunda, orneklem grubunun olusturan ogretmenlerin sadece %16.18’inin lisansustu egitim yaptigi, %66.20’sinin kirada ikamet ettigi ortaya cikmistir. Ayrica, ogretmenlerin %16.66’si hayatini idame ettirebilmek icin gelir getiren ek bir is yapmak durumunda kalmaktadir.