We propose to develop a differential absorption spectrometer that is small enough to be compatible with a test package in a bremsstrahlung test of electronics. In contrast to previous spectrometers, which use individual filter-detector combinations, the present instrument consists of concentric hemispherical shells. This design minimizes the spectrometer's mass, allowing it to be placed in front of or near a test package. There it measures the x-ray spectrum from a single location on or near the package. Time resolution will be achieved by use of all optical dose rate diagnostics already under development for a complementary project. In Phase I we will design, build and evaluate a prototype. Upon satisfactory completion of Phase I, we will build and test an instrument with up to 18 channels in Phase II.
