Proof-of-Principle Time-Resolved Bremsstrahlung Spectral Measurement for Intense, Low-Endpoint (<300 keV) Pulsed Sources

In a proof-of-principle test, we measured how the L-3 Pulse Sciences MBS (∼200 keV peak voltage) Bremsstrahlung spectrum changed in time using a pair of filter-fluorescer channels, one at 41 ± 18 keV and another at 87 ± 27 keV. This demonstrates an approach for measuring a time-resolved bremsstrahlung spectrum for SGEMP applications, albeit with coarse energy resolution (30-45%). Using filter fluorescers and detecting the resultant X-rays with plastic scintillator PMTs, there is adequate sensitivity and dynamic range to correlate spectra from two sources, MBS and PITHON, which differ by a factor of up to ∼100x in brightness (from 1 to 100 rad CaF2 at the spectrometer entrance). For such a correlation, no hardware changes are required-only the PMT gains need to be changed. The time resolution of the measurement is expected to be 2 ns.