Ümit Turgut

X-Ray attenuation coefficients at different energies and the validity of the mixture rule for compounds around the absorption edge

Abstract The total mass attenuation coefficients for the elements Co, Mn and Co2O3, compounds CoCl2.6H2O, CoSO4, CoSO4.7H2O, MnCO3, KMnO4, MnCl2.2H2O, and MnCl2.4H2O were measured at different energies between 4.508 and 11.210 keV using a secondary excitation method. Ti, Co, Ni, Cu, Zn, As, Se were chosen as secondary exciter. Gamma rays (59.5 keV) emitted from an 241Am annular source were used to excite a secondary exciter and Kα (K–L3, L2) lines emitted of a secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. It was observed that the mixture rule method is not suitable for determination of the mass attenuation coefficients of compounds, especially at energy that is near the absorption edge. Obtained values were compared with theoretical values.

Measurement of the Kα and Kβ X-rays polarization degree and polarization effect on the Kβ/Kα intensity ratio

Abstract The linear polarization degree of K α and K β X-rays of some elements in the atomic range 57⩽ Z ⩽69 has been measured. In addition, the polarization effect on the intensity ratio of these elements is investigated. It is found that the K β X-rays are more polarized than K α X-rays. The polarization effect on the K β /K α intensity ratio was investigated. Because the polarization of characteristic K X-ray is not found in the literature the comparison was not made with other experimental and theoretical results.

Measurement of L shell fluorescence yields of seven elements in the atomic number range 79 ≤ z ≤ 92 using photoionization

L shell fluorescence yields were measured for Au, Hg, Tl, Pb, Bi, Th and U using a Ge(Li) detector. The targets were excited using 59.5 keV γ-rays from a 241 Am radioactive source of strength 400 MBq. The results obtained were compared with the theoretical values and other measured values. This comparison shows that the present results are in good agreement with earlier experimental and theoretical results.

L X-ray intensity ratios in heavy elements at 59.5 and 122 keV photons

The L shell X-ray intensity ratios ILα/ILβ, ILα/IL1 and ILα/ILγ for Ta, W, Re, Au, Hg, Tl, Pb, Bi, Th and U have been measured at excitation energies of 59.5 and 122 keV with a Si(Li) detector. Measurements have been performed using Am-241 and Co-57 radioisotope sources. A comparison is made of the experimental results with calculated values obtained using theoretical X-ray emission rates, subshell ionization cross-sections, subshell fluorescence yields and Coster-Kronig transition probabilities. A fairly good agreement is observed between experimental and theoretical values.

Effect of conceptual change text approach on removal of students’ misconceptions about heat and temperature

This study focuses on students’ misconceptions regarding heat and temperature, the effectiveness of conceptual change text instruction on students’ understanding of heat and temperature and their attitudes towards science. Conceptual change and traditional instruction methods were used as teaching methods in the study. The results showed that the students have misconceptions and the experimental group students performed better with respect to the success in eliminating the misconception compared to the control group. In addition, it has been found that there was no significant difference between the attitudes of students in the experimental and control groups both before and after teaching. Teaching strategies can be used to determine the misconceptions and enhance students’ understanding. Moreover, results showed that there were no statistically significant differences of post-test and delayed test.

Determination of total attenuation cross sections of Ti, Fe, Ni, Zn between 4.551–111.898 keV energy range

The total attenuation cross sections in elements Ti, Fe, Ni and Zn for Kα and Kβ group of liens of element 22≤Z≤92 by using tranmission method. K X-rays of seconder excitor were counted by a Ge(Li) detector with resolution 190 eV at 5.9 keV. The experimentally mesured attentuation cross sections have ben found in a good agreement with the theoretical values of Stom, Israel and Hubbell, Seltzer.

The viewpoints of physics teacher candidates towards the concepts in special theory of relativity and their evaluation designs

In this study, the viewpoints of physics teacher candidates at undergraduate level towards the concepts in special theory of relativity and the interpretations they made about these concepts were investigated. The viewpoints of the teacher candidates towards the concepts in the subject of special theory of relativity were revealed with six open ended questions prepared by the writers who are physics teachers as well. The research is a qualitative study and the study was conducted with eighteen teacher candidates. In this study, case study, one of the methods of qualitative research, was used. The study group of the research was chosen by convenience sampling. The data collected via open ended questions was analysed by descriptive analysis method. According to the results of the study, it was revealed that most of the students have not been introduced to the special theory of relativity and the concepts related to them. It could be stated that the candidates had difficulty with the relativity of time and its reference frame. Most of the teacher candidates could not make the interpretation that the speed of light was the limit speed and no other object could reach that speed.