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Multi-User Equipment approved in grant 19/02477-5: two-dimensional X-ray detector

Abstract

The Bruker D8 Discover diffractometer at the UFABC Multiuser Experimental Center (CEM) is a scientific facility that serves a community that currently has over 300 users distributed among both graduate students and local and external researchers that make use of the CEM facilities for development of various research projects. This equipment is dedicated to X-ray diffraction analysis of the atomic structure of solids like thin films, single crystals and polycrystalline samples, either at room temperature or under high and low temperature conditions. For this purpose, the diffractometer has an Euler cradle, a temperature chamber (for measurements between -190 ° C and 1500 ° C) and a cryostat (for measurements at very low temperatures up to 2 K), as well as a Mo microfocus x-ray source and a two-dimensional x-ray detector. This configuration allows this diffractometer to be used in material analysis using different X-ray diffraction techniques, such as measurements of crystallographic texture and residual stresses, grazing angle diffraction, reflectometry, and polycrystalline / powder diffraction at low and high temperatures, as well as single crystal diffraction and also SAXS. This shows how the D8 Discover diffractometer is a very versatile and unique device. Nevertheless, in recent years it has been underused because the old two-dimensional X-ray detector (Hi-Star Bruker) has reached the end of its useful life and can no longer be repaired. Two-dimensional detectors are best suited for use with x-ray point sources like the microfocus sources as they greatly increase the speed of measurement by their ability to simultaneously record scattered intensities at various angles within their active detection area, compensating for the low intensity of x-ray source. Old area detectors like Hi-Star Bruker are gas proportional counters. Due to the decrease in internal gas pressure over time, such detectors lose efficiency and stop functioning if not periodically repaired with gas refilling. For this reason and because the manufacturer no longer offers maintenance service for this type of equipment, the current detector is now inoperative and this way we request its replacement by a new and more modern two-dimensional x-ray detector, which does not require periodic maintenance. Currently, the most suitable option for use in the CEM D8 Discover diffractometer, if not the only one, is Bruker's LYNXEYE XE-T two-dimensional detector, not only because it is fully integrable with the diffractometer's physical structure, but also because it is the most suitable for Mo radiation detection. Added to these features, there is also the advantage that this detector has sufficient energy resolution to filter Kbeta radiation without the need for physical filtering. According to the manufacturer, the use of the LYNXEYE XE-T area detector should provide up to a 450-fold increase in data acquisition speed when compared to a 0D detector, thereby considerably reducing the time of a measurement. Thus, it is expected that, with the replacement of the current area detector, much faster and better-quality X-ray diffraction measurements will be possible, greatly benefiting the ongoing research projects at UFABC that require X-ray diffraction analyses, especially those requiring special settings (temperature and special geometries). (AU)

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