Time-sensitive search for chemical agents in γ-ray spectra

We have performed a search for Sarin, a chemical warfare agent, in luggage-sized sealed containers in order to illustrate how effectively and quickly a search could be conducted in a fixed installation at airports, embassies, government buildings, military installations, and other public areas. A portable neutron generator and a Californium source were used, generating up to 108 neutrons per second, that penetrate into a container and are capable of exciting a sample in a period of approximately 10 s, to produce enough γ radiation that target elements within the sample can be identified. In the vast majority of cases, there is no chemical agent present, so the question becomes how long to search. We show results of tests for sensitivity of this technique as a function of time. We have also developed background or typical samples with no chemical agent present to estimate the false positive rate for this technique.