A convergent neutron lens based on glass capillaries

The properties of a convergent neutron lens in the form of an assembly of bent glass capillaries have been experimentally investigated. Each capillary is a conical tube with a length of 22.5 cm, an entrance diameter of 0.25 mm, and an exit diameter of 0.17 mm. The spectrum of thermal neutrons incident on the lens entry is formed on the beam of the IR-8 reactor by means of a diamond microcrystalline filter and investigated with a time-of-flight spectrometer. The spatial distribution of the neutron beam at the exit from the lens is measured using the position-sensitive image plate detector. The measured focal length of the lens is 75–80 mm. The possibility of focusing neutrons with an increase in the local beam density at the lens axis by a factor of 4.9 is demonstrated.