Comparative study of nondoped and Eu-doped SrI₂ scintillator

Optical and scintillation properties of nondoped and Eu 3% doped SrI₂ crystals grown by the Vertical Bridgman method were investigated. Eu-doped crystal showed an intense single band emission at 430 nm due to the Eu²⁺ 5d-4f transitions in both photoluminescence and scintillation while the nondoped crystal had a complex spectral shape. The latter emission consists of mainly four bands: 360 nm, 540 nm, 410 nm and 430 nm. The origins of 360 nm and 540 nm were self-trapped exciton and unexpected impurity, respectively. The origins of 410 and 430 nm lines were ascribed to F center in different I sites. Under ¹³⁷Cs γ-ray irradiations, both crystals showed a clear photoabsorption peak. The scintillation light yields of the nondoped and Eu-doped SrI₂ resulted 33,000 ph/MeV and 82,000 ph/MeV, respectively. The energy resolution at 662 keV of Eu-doped was 4% while that of the non-doped SrI₂ was 8%.