Current Status of the Wavelenght Dispersive System of the XRF Beamline

C. A. PÉREZ; H. J. SÁNCHEZ

Campinas, Brasil

Congreso; RAU 19; 2009

This work presents the status of the wavelength dispersive system that is being currently commissioned in the XRF beamline of the LNLS. X-Ray Fluorescence using energy-dispersive setups is a well-known technique. It has several advantages and the range of applications is increased everyday. In addition, many other techniques are derived from conventional XRF, for instance total-reflection analysis, micro-analysis, etc.   A different approach for detecting characteristic radiation is proposed by the so-called wavelength dispersive systems. With this setup, fluorescent radiation is filtered by a perfect crystal and, via Braggs’s law, selected energies are detected by a proportional counter. In this configuration, the energy resolution is improved several orders of magnitudes at the cost of a longer measuring time.   A wavelength dispersive system is currently mounted and in commissioning in the XRF beamline of the LNLS. At present the system has been located in a tentative place of the beamline and the first alignments have been carried out. In this stage a thin Si (111) curved crystal (Johann optics) is being used and several samples are under study for the characterization of the equipment. After several manipulations we reached an energy resolution of 40 eV, which is a third of a typical solid state detector but one order of magnitude worse than the resolution expected for a system like this one.   More work will be carried out in order to obtain the normal parameters for this kind of apparatus and in order to mount the system in a fixed place of the beamline. In this way, in a near future this equipment will be available for external users.