Spherical neutron detector for space neutron measurement

A novel neutron detector has been developed to measure energy spectra of space neutrons in a spaceship. The detector consists of a spherical polyethylene moderator with a diameter of 30 cm and 19 pairs of 6Li- and 7Li-glass scintillators arranged along the orthogonal x-, y-, and z-axes of the sphere. The pairs can distinctively detect thermal neutrons in some radiation fields, where other radiation exists, by subtracting the number of detected events of the 7Li-glass scintillator from that of the 6Li-glass one. Hence the detector can clearly obtain the thermal neutron flux distribution in the spherical moderator even in such fields. The detector was applied to the measurement of monoenergetic and 252Cf neutrons. The characteristics of the detector were studied by comparison with the simulations.