2013 R&D 100 Winner
Traditional thermal neutron detectors are proportional counter tubes, filled with helium or boron trifluoride, which react with impinging neutrons and generate a charge proportional to the Q-value, or energy value, of the reaction. They have a host of uses in security, defense and nuclear safety; but the gases used are either highly toxic or in increasingly short supply.

LISe: A High-Efficiency Thermal Neutron Detector, developed by Y-12 National Security Complex and Fisk Univ., offers an alternative to existing technologies. LISe contains the neutron absorber within the semiconductor itself. LISe, based on the 6LiInSe2 crystal, is the first large, single-crystal lithium semiconductor of high resistivity that directly detects thermal neutrons. Every fourth atom in the semiconductor is lithium, so the average distance traversed by a thermal neutron before capture by the detector is just 0.1 mm. This enables a factor-of-25 improvement in both detector thickness, compared to helium tubes, and efficiency, compared to coated-silicon diode.

High-efficiency thermal neutron detector

Y-12 National Security Complex
Fisk Univ.

Development Team

The LISe: A High-Efficiency Thermal Neutron Detector Beam Development Team
Ashley Stowe, Principal Developer, Y-12 National Security Complex
Zane Bell, Y-12 National Security Complex
Arnold Burger, Fisk Univ.