Stabilized, hand-held, gamma-ray verification instrument for special nuclear materials

For many years, Los Alamos has developed intelligent, hand-held, search instruments for use by non-specialists to search for special nuclear materials (SNM). The instruments sense SNM by detecting its emitted radiation with scintillation detectors monitored by digital alarm circuitry. Now, we have developed a new hand-held instrument that can verify the presence or absence of particular radioisotopes by analyzing gamma-ray spectra. The new instrument is similar to recent, microprocessor-based, search instruments, but has LED detector stabilization, three adjustable regions-of-interest, and additional operating programs for spectrum analysis. We call the new instrument an SNM verification instrument. Its spectrum analysis capability can verify the presence or absence of specific plutonium isotopes in containers or verify the presence of uranium and its enrichment. The instrument retains the search capability, light weight, and low-power requirement of its predecessors. Its ready portability, detector stabilization, and simple operation allow individuals with little technical training to verify the contents of SNM containers. 5 refs., 5 figs.