Nucsafe’s Guardian Glass is available in various forms, including: fiber, rods, discs, plates and tubes. The glass utilizes the neutron sensitivity of 6Li for the detection of neutrons. The nucleonic detection process is characterized by the6Li absorption of a thermal neutron and generation of an alpha particle and a triton: 6Li +n → α + Triton + 4.8 MeV.
The 4.8 MeV kinetic energy imparted to the alpha and triton excite the Ce3+ in the glass which in turn emits 395-432 nm wave length photons upon returning to the ground state. The efficiency of capture cross section for 6Li is a function of the neutron’s energy. Unlike isotopic gamma signatures that are mono-energetic, the isotopic neutron signatures are a spectrum. The graph below is representative of the 252Cf neutron spectrum response of the Guardian Glass. This graph shows that approximately 92% of the neutrons striking a 3.5 mm thick detector are captured. Most neutron sources have gamma rays associated with their neutron spectrum