Measurement of K X-ray fluorescence cross-sections, fluorescence yields and intensity ratios for some elements in the atomic range 22⩽Z⩽68

FLUKA Simulations of Kβ/Kα Intensity Ratios of Copper in Ag-Cu Alloys

The numerical simulations of Cu Kα and Cu Kβ fluorescence lines induced by Rh X-ray tube and by monoenergetic radiation have been presented. The copper Kβ/Kα intensity ratios for pure elements as well as for Ag-Cu alloys have been modeled. The results obtained by use of the FLUKA code, based on the Monte-Carlo approach, have been compared to available experimental and theoretical values. A visible relationship was found between the simulated Kβ/Kα intensity ratios and the copper content of the Ag-Cu alloy: as the Cu content increases, the Kβ/Kα coefficient decreases. The results can play role in elemental material analysis, especially in archaeometry.

Investigation of CdTe, GaAs, Se and Si as Sensor Materials for Mammography

Despite the benefits of mammography investigations, some studies have shown that X-ray exposure from the mammography screening itself can statistically cause breast cancer in a small fraction of women. Therefore, a dose reduction in mammography is desirable. At the same time, there is a demand for a higher spatial resolution in mammographic imaging. The most promising way to achieve these goals is the use of advanced photon-processing semiconductor X-ray detectors with optimum sensor materials. This study addresses the investigation of the optimum semiconductor sensor material for mammography in combination with the photon-processing detector Medipix3RX. The influence of K-shell fluorescence from the sensor material on the achievable contrast-to-noise ratio is investigated, as well as the attenuation efficiency. The three different sensor materials, CdTe, GaAs, and Si are studied, showing advances of CdTe-sensors for mammography. Furthermore, a comparison of the contrast-to-noise ratio between a clinical Se-detector and Medipix3RX detectors with Si- and CdTe-sensors is shown using a self-produced mammography phantom that is based on real human tissue.

Determination of K-L total vacancy transfer probabilities using a weak gamma source in 2π geometrical configuration

The K shell intensity ratios K(β)/K(α) for 9 elements in the atomic range 40 ≤ Z ≤ 50 have been determined using a weak (133)Ba gamma source at excitation energy of 80.997 keV. The K-L total vacancy transfer probabilities (η(KL)) for these elements have been determined. K x-rays emitted by samples were detected using a CdTe semiconductor detector (resolution <1.2 keV for the (57)Co gamma ray at 122 keV) with a 2π solid angle. The measured values were compared with the theoretical values calculated using Scofield's tables based on the Hartree-Slater and Hartree-Fock theories and available experimental values.

Unique Properties of Thermally Tailored Copper: Magnetically Active Regions and Anomalous X-ray Fluorescence Emissions

When high-purity copper (>/=99.98%(wt)) is melted, held in its liquid state for a few hours with iterative thermal cycling, then allowed to resolidify, the ingot surface is found to have many small regions that are magnetically active. X-ray fluorescence analysis of these regions exhibit remarkably intense lines from "sensitized elements" (SE), including in part or fully the contiguous series V, Cr, Mn, Fe, and Co. The XRF emissions from SE are far more intense than expected from known impurity levels. Comparison with blanks and standards show that the thermal "tailoring" also introduces strongly enhanced SE emissions in samples taken from the interior of the copper ingots. For some magnetic regions, the location as well as the SE emissions, although persistent, vary irregularly with time. Also, for some regions extraordinarily intense "sensitized iron" (SFe) emissions occur, accompanied by drastic attenuation of Cu emissions.

The polarization of X-rays and magnetic photoionization cross-sections for L3 sub-shell

The alignment of atoms with inner-shell vacancies resulting from ionization by photons was investigated by measuring the anisotropic emission of L shell X-ray lines. The X-ray line intensities were measured using an Si(Li) detector and radioisotope photon source in various emission angles. It was observed from measured intensities that Lalpha and Ll X-ray intensities for the L(3) sub-state depended on the emission angle, meaning that Lalpha and Ll X-rays had an anisotropic spatial distribution. Thus, the Lalpha to Ll intensity ratios for a set of elements were determined and alignment parameters for each element were obtained using these ratios. Also, the empirical values of the L(3) magnetic sub-state photoionization cross-sections for m(j)=3/2 and 1/2 were evaluated using the determined alignment parameters, sub-state photoionization cross-sections and the Coster-Kronig transition probabilities.