Numerical Simulation of Radiation Anisotropy of the Pyroelectric Neutron Generator

The pyroelectric neutron generator is a compact source of fast neutrons with an energy of 2.45 MeV and a yield up to ∼10⁴ neutrons/s. The device is designed for calibration of low-background neutrino and dark matter detectors and may also serve as an alternative to traditional radioactive sources of fast neutrons in physical research and practical work. Numerical simulation of the angular distribution of neutrons emitted by the pyroelectric generator with the D(d, n)³He reaction proceeding within it was performed in order to calculate the neutron yield in the full solid angle and in a given direction correctly. The angular distribution was found to be anisotropic: the neutron yield increased in the direction of motion of incident deuterium ions. This anisotropy was as large as ∼25% at a maximum energy of 28 keV of incident particles. The anisotropy increased nonlinearly with the ion energy: it reached ∼70% at 50 keV and a monoenergetic flux, but was virtually zero below 10 keV. The obtained angular distribution is similar to that of neutrons in the case of a 15-keV monoenergetic flux of deuterium ions.