DESIGN OF AN OPTIMAL ROSS FILTER SYSTEM FOR X-RAY-SPECTRA MEASUREMENTS IN THE RANGE OF 8.98-88-KEV

This article describes wide-band Ross filter spectrometers for short-pulse plasma devices. The spectrometer consists of a number of channels, each representing a Ross filter pair in conjunction with x-ray detectors. Sensitivity bands of these channels cover the energy interval of interest without gaps. We consider as optimal the spectrometer whose channels have constant response within their sensitivity ranges and minimal response outside them. The main innovation is the addition of light material into one filter of the Ross pair, which reduces significantly (up to 5 times) the response outside the sensitivity range. Examples are presented of the optimal six-channel (8.98-18.99-29.2-38. 92-50.24-67.42-88 keV) spectrometers with three types of detectors: Pb calorimeters, CsI scintillators, and Al2O3 thermoluminescent detectors and filters of readily available materials. The effect of uncertainty in x-ray cross sections and material thicknesses and the effect of filter-scattered photons hitting the detector on the accuracy of measurements are calculated. © 1995 American Institute of Physics.