What type of neutrons do neutron survey monitors primarily detect?

Neutron survey monitors primarily detect thermal neutrons because these are neutrons that have been slowed down to thermal energies, which typically range from approximately 0.025 eV to a few eV. Thermal neutrons are particularly significant in various applications, such as neutron activation analysis, nuclear reactors, and radiation safety monitoring, due to their high interaction cross-section with many materials, including hydrogenous substances like water and organic materials.

In many neutron detection technologies, such as those utilizing boron or lithium as the detection medium, the reaction that occurs with thermal neutrons results in a measurable signal. This sensitivity to thermal neutrons is essential for accurate dosimetry and radiation monitoring in environments where thermal neutron interactions are predominant.

The detection of fast neutrons, while possible, typically requires different types of equipment that incorporate other detection principles. Similarly, the options of alpha and beta neutrons do not actually exist; alpha and beta radiation refer to different types of charged particles, rather than neutron classifications. Therefore, thermal neutrons are the primary focus for neutron survey monitors due to their prevalence and the effectiveness of detection methodologies designed to respond to them.