Abstract: A scintillation type neutron detector is provided herein for the measurement of neutrons with optimum neutron sensitivity and minimum gamma sensitivity. A large diameter nuclear radiation insensitive photomultiplier tube is optically connected to a scintillating medium which is responsive to thermalized neutrons. The neutrons available for detection are thermalized by a neutron moderating material adjacent to the scintillator medium. Enclosing and shielding the photomultiplier, the scintillator medium, and the moderator is a combined lead and borated silicone resin housing.