Keywords

soft x-ray, high performance, x-ray window, absorption

Abstract

X-ray windows are used in sources and detectors to separate the neighborhood of the x-ray generation or detection from the use environment. While each use has its own requirements, there are some principles that should be used in designing an optimal x-ray window. Because x-rays are absorbed to some extent by all materials, minimizing absorption is one criterion in preparing windows. Also, for most uses there is a pressure difference across the window so that ensuring pinhole-free structure and sufficient mechanical strength to support the differential is another criterion for window design. Traditionally, absorption is minimized by fabricating the window with lower atomic number (low Z) elements such as Be, B , or C. However, the wavelength (energy) region of interest becomes a very important complicating factor. Over the years many different materials have been used as windows for soft x-rays. A primary use has been for proportional counters. More recently interest has developed for Si(Li) detectors. The materials used to date for proportional counters include: polypropylene, lexan, and formvar^1-4. Materials used for Si(Li) detectors have been Be, BNx, formvar, a-C:H (diamond-like carbon), and mylar^5. The purpose of this paper is to discuss the design of x-ray windows with particular emphasis on windows for detectors in the soft x-ray region. This is because existing windows can typically be made thin enough to have very good transmission for the harder x-rays.

Original Publication Citation

Raymond T. Perkins, David D. Allred, Larry V. Knight, and James M. Thorne, "Design of high performance, soft x-ray windows," Advances in X ray Analysis, 33, Charles S. Barrett, Editor (Plenum, New York, 199), pp. 615 622. http://www.icdd.com/resources/axasearch/search_based_on_vol.asp