Neutron-Stimulated Gamma Ray Measurements for Chlorine Detection

Applications of neutron-gamma analysis for chlorine determination in different materials (e.g., solids, aqueous solutions, and surface contaminations) are discussed. Solid samples were measured with a pulsed fast/thermal neutron analysis (PFTNA) system consisting of a pulsed neutron generator and sodium iodide gamma detectors and an associated particle imaging (API) system consisting of a neutron generator (with a built-in alpha detector) and sodium iodide gamma detector; all sample measurements were made under similar conditions (neutron flux values and detector-side area for crossing gamma flux). The advantages of PFTNA over the API method were demonstrated based on comparison of metrological parameters (i.e., minimal detectible level for a 1-h measurement period and clock time required to reach 5% measurement accuracy). For these reasons, the PFTNA system in scanning mode effectively identified areas of artificial chlorine contamination in the field. Paired with GPS, a chlorine contamination map was created from PFTNA scanning results; this map accurately identified the actual position and size of chlorine contaminated locations in the field. Chlorine-contaminated areas of ~4.5 m
²
were effectively located within the ~500 m
²
field during a ~2-h scanning period. Based on the results from this work, promising directions for further application of the PFTNA method are disclosure of chlorine contamination in soil and measurements of marine water salinity.