Assessment of Sm2+-doped SrI2, EuI2, and YbI2 for near-infrared scintillator applications

SrI 2 :Eu 2+ and CaI 2 :Eu 2+ are two of the brightest known scintillators , but they both suffer from self-absorption. Their respective undoped isostructural compounds EuI 2 and YbI 2 are not suitable for scintillation due to the additional problem of concentration quenching. These compounds can however be doped with Sm 2+ to turn them into near-infrared emitting scintillators , with the additional benefit that the self-absorption probability of the Sm 2+ emission is low. Here, the scintillation properties of SrI 2 :1%Sm 2+ , EuI 2 :4%Sm 2+ , and YbI 2 :1%Sm 2+ single crystals are assessed which were grown by the vertical Bridgman technique . SrI 2 :1%Sm 2+ and EuI 2 :4%Sm 2+ fall within the ideal wavelength range for detection with silicon based photodetectors and are spectroscopically very similar to each other. However, the key difference is that the scintillation decay time of EuI 2 :4%Sm 2+ is 1 . 1 μ s , much shorter than the 1 . 8 μ s of SrI 2 :1%Sm 2+ . Both SrI 2 :Sm 2+ and EuI 2 :Sm 2+ are identified as interesting candidates for further optimisation in the development of near-infrared emitting scintillators .