ABSTRACT
The chapter focuses on the possibility of letting thermal neutrons propagate along suitable waveguides with decreasing small transverse cross-sections. It speculates about the possible applications of neutron optics and neutron fibers to boron neutron capture therapy (BNCT) and discusses some preliminary attempts. In order to perform BNCT, the required beams of thermal neutrons are extracted typically from nuclear reactors. The chapter summarizes some recent work on the possible confined propagation of thermal neutrons for the smallest transverse dimensions which could presumably allow activity at the nanometer scale. It also summarizes the quantum mechanical three-dimensional treatment of the confined propagation of slow neutrons. The experimental assessment of the behavior of slow neutrons and its comparison with quantum mechanical predictions at decreasing scales constitutes a subject of considerable interest in the fundamental research.
