K shell Radiative and Total Vacancy Transfer Probabilities of Barium & Thallium from Internal Conversion Electron Sources

K shell Radiative and Total Vacancy Transfer Probabilities of Barium & Thallium from Internal Conversion Electron Sources

The information obtained from X-ray fluorescence parameters is very important in the study of some basic phenomena, in atomic molecular and radiation physics. This demands for accurate values of XRF parameters such as shell wise and sub-shell wise X-ray fluorescence yield, fluorescence X-ray production cross-section, shell and sub-shell intensity ratios, K to L vacancy transfer probabilities and so on. Nuclear processes like orbital electron capture or internal conversion of gamma transition and interaction of photons or charged particles give rise to X-ray fluorescence. It is reported that the probability of emission of X-rays by decay process is different from the probability of emission of X-rays by photoionisation[1-3]. The K shell XRF parameters of elements have been extensively studied by several researchers by photon exciation methods and varieties of detectors [4-9]. But there are not many reports on the measurements of K shell X-ray intensity ratios of elements following decay processes. This may be due to the requirement of the radioactive sources of the order of 100mCi and preparing many electron capture and internal conversion sources of this strength may be a difficult task. In view of this, we have made an attempt to study the effect of internal conversion on the probability of X-ray emission of thallium and barium by determining K shell intensity ratios, K ?? Li, K-M radiative and K-L total vacancy transfer probabilities from weak internal conversion sources Hg203 and Cs137respectively. To examine the effect of decay process on X-ray emission the K shell fluorescence parameters determined are compared with the theoretical values and other experimental results obtained using radioactive decay and photon excitation methods. The dissertation consists of five Chapters. In the first Chapter, we introduce the project work carried out. In Chapter 2, we present the brief theory of XRF and literature survey. It consists of two sections; in section 2.1, we give the theoretical aspects of the K X-ray fluorescence and in section 2.2, we present the literature survey related to the determination of K X-ray intensity ratios and vacancy transfer probabilities through photoionization methods and decay processes. Chapter 3 deals with experimental details such as the radioactive sources, detector and electronic modules used in our experiment, the experimental arrangement and standardization of spectrometer, and experimental procedure adopted in the collection and analysis of the data. In Chapter 4, we present the results on K X-ray intensity ratios and vacancy transfer probabilities along with the theoretical, semi-empirical and others experimental values. In Chapter 5, we give the conclusions.

P V Sreevidya

Department of Physics