Measurement of L X-ray production cross sections and relative intensities of some lanthanide compounds depending on the temperature

L X-ray intensity ratios for CeO2, Sm2(SO4)3, Ho2O3, and Yb2O3 compounds were experimentally investigated. The measurements were gauged following excitation by 59.54 keV γ-rays from a 100 mCi 241Am radioactive annular source at different temperatures in situ. Temperature change occurred between 50 °C and 400 °C. L X-ray emission spectra were obtained by using a solid-state Si(Li) X-ray detector. L X-ray production cross sections, intensity ratios, and full-width half maximum (FWHM) values for the compounds were determined by evaluating the emission spectra varying with the temperature. According to the results obtained, it was observed that Lβ1 X-rays were less influenced in comparison with Lα X-rays while Lα X-rays were also less influenced in comparison with Lβ2 X-rays.

Quasi-Static Thermal Modelling of Multi-Scale Sliding Contact for Unlubricated Brush Seal Materials

Prediction of the contact temperature between two materials in high speed rubbing contact is essential when analysing the wear mechanism and modelling wear rate for unlubricated contact. Conventionally the assumptions used for a pin-on-disc configuration are either a steady heat source at the contact for slow speed rotation or an annular source along the rubbing track at high rotating speeds. In this paper, the rotating heating source is solved using an in-house finite element method (FEM) code. This captures the full geometry and rotating speed of the rubbing bodies. The transient heat transfer problem is modelled in a quasi-static way: eliminating the computational cost of a transient 3D simulation. This reduced-order model is analytically shown to be suitable for contact temperature prediction over a wide range of rotating speeds, anisotropic thermal conductivity, and non-uniform thermal boundary conditions. The model calculates heat partition accurately for a thin rotating disc and short pin combination, which cannot be predicted using existing analytical solutions. The quasi-static numerical model and in-house FEM solver are validated against Ansys Mechanical and experimental measurements using infrared thermography. The numerical result demonstrates that the annular source assumption can significantly under-predict the contact temperature, especially at the rubbing interface. Explicit modelling of a thin disc results in a higher heat partition coefficient compared with the commonplace semi-infinite length assumption on both static and rotating components. Furthermore, the thermal anisotropy for bristle tufts is numerically evaluated, and the tuft-on-disc configuration is compared to the pin-on-disc configuration. Despite the effective thermal conductivity in the bristle tuft being approximately one order of magnitude lower than along the bristle length (treating the bristle as a porous medium), its impact on heat partition and contact temperature is shown to be limited.

Photon-Induced L-Shell X-Ray Production Cross Sections for Lanthanides at 59.54 keV

The Ll, Lα and Lβ X-ray production cross sections for Pr, Nd, Sm, Eu, Gd and Tb elements were determined using a reflection geometry. The excitation was performed with a 241Am radioactive annular source and the L X-rays emitted from targets were counted with a high-resolution Si (Li) detector. The experimental values were compared with other available experimental results and theoretical data. An agreement is observed between the measured and other experimental results or theoretical data.

Comparison of Elemental Sensitivities Induced by Radioisotope and Secondary Target Excitation for Simultaneous Multielement X-Ray Analysis

SummaryThe major advantage of secondary-target X-ray fluorescence analysis is the enchancement of sensitivity and detection limit of an element or small group of elements with similiar atomic numbers by selecting a target material which produces X-rays slightly higher than the absorption edges of the analysis of interest. Secondary target excitation systems are, however, being employed for simultaneous determinations of a large range of elements. Thus, it was decided to compare the application of a simple secondary target X-ray fluorescence system with excitation from a Cd-109 annular radioisotope source.A simple secondary target X-ray fluorescence system was constructed and optimized which operates at less than 800 kilowatts. The “relative” elemental sensitivities of this system. and a radioisotope system with a Cd-109 annular source were compared by the analysis of the 1-2-3-multi-spectral standard from Chemplex which contains 1.23% of 53 elements. The characteristic X-rays were collected with the same Si(Li) detector and analyzed with the same Apple lie microprocessor with a Nucleus ADC/interface card. Finally, the secondary target system described herein with a molybdenum X-ray tube and zirconium or cadmium target produced similiar elemental sensitivities as a Cd-109 annular source of about 7.5 mCi and 5.0 mCi intensity respectively.

The Recessed Source Geometry for Source Excited X-Ray Fluorescence Analysis

Different geometries are considered for source excited energy-dispersive X-ray fluorescence (EDXRF) analysis Systems, including the recessed source geometry introduced in the present work. The calculated physical excitation-detection efficiencies, for the side (or annular), central, receded and recessed source geometries are presented as a function of the target to source distance, for Ca, K, S and Si targets excited with a Fe-55 XBF-3 X-ray source and xenon filled gas proportional scintillation counters. The last two geometries present in gênerai the highest efficiencies. The recessed source geometry présent the best performance with peak efficiencies a factor of 3.3 better than those for the standard side or annular source geometries.