Advanced Compact X-Ray Spectrometer with High Resolution and Efficiency

The combination of X-ray absorption spectroscopy (XAS) with x-ray emission spectroscopy (XES) provides unique diagnostic analysis of both the structure and chemical composition of complex heterogeneous materials. The penetration of X-rays make this method ideal for studying and optimizing material properties under realistic, real time reaction conditions with simultaneous analysis of reaction products (in-operando). The full potential of XAS and XES measurements are limited by the detectors of the spectrometers. This proposal investigates a new detector design that will result in a highly efficient, easy to handle, low- cost, high-resolution detection system with excellent background suppression. This system is based on non-diffractive optics comprised of fused and directed glass capillary tubes that will be used to collimate the x-rays, allowing the use of a plane crystal as the wavelength selective element. This x-ray optic is a new design concept and the focus of this proposal. The main benefits of the proposed system are; a large energy range is accessible without modifying the system, a large collection angle is achieved per detection unit: 4-5% of the full solid angle, easy integration in complex and harsh environments is enabled due to the use of a pre-collimation system as a secondary source for the spectrometer, and background from a complex sample environment can be easily and efficiently suppressed. As a result of the Phase I research the following objectives have demonstrated a) produce 90% open area polycapillary glass structure suitable for creating x-ray optic structures b) tapering the polycapillary structure to produce x-ray optics to the desired profile c) measure key x-ray transmission parameters of the x-ray optic at BNL, and d) simulate key design parameters of x-ray optics, e) and developed several detector concepts incorporating the optic. In Phase II, x-ray optics optimized for the detector application will be fabricated and tested. Test results will be compared with computer models for agreement. These optics will be packaged in a holder suitable for use in vacuum and extreme temperature environments. Two detector prototypes that incorporate the optics will be tested as part of Phase II. This development program will benefit of x-ray detectors beyond those used in synchrotron radiation facilities. For example, it could replace the conventional energy dispersive detectors like silicon drift diodes in scanning electron microscopes (SEM).