A new intense neutron generator and high-resolution detector for well logging applications

Data analysis for preliminary conceptual model design, Vadose Zone Monitoring System (VZMS), McClellan AFB. 1997 annual report

“…PVC casing, which is the material most often used in environmental applications, is not well suited for neutron logging because of its high chlorine content. Chlorine has a very large capture crosssection for thermal neutrons (Celata et al, 1996) and greatly reduces the thermal neutron count, thereby reducing sensitivity. Concrete grout has the advantage over other backfill materials of having a more or less constant moisture content with time, but a high moisture content nonetheless, resulting in a high background neutron count.…”