Europium Doped Lithium Iodide LiI(Eu)
LiI(Eu) is а scintillator mostly used for thermal neutron detection. Neutrons are detected in 6LiI(Eu) through their interaction with the 6Li atoms of the material through the reaction:
This reaction is particularly suitable since no γ-ray is released. The peak for thermal neutrons appears at equivalent γ-ray energy of about 3 MeV, permitting effective discrimination against all natural y-rays.
LiI(Eu) has а light yield of about 30-35% of NaI(TI). The emission consists of а broad band with а maximum at 470 nm. Due to some self absorption in the crystal, large crystal dimensions will degrade the energy resolution.
The decay time for y-rays was measured to be 1.4 µs at room temperature (300К). For the ratio between the response to γ-rays and α-particles/ tritons (light yield per MeV), values around 0.6 are reported. LiI(Eu) is very hygroscopic and is therefore supplied in hermetically sealed detector assemblies.