Photoluminescence and scintillation properties of undoped and Tl-doped Cs2BaBr4 crystals

Abstract

Photoluminescence and scintillation properties of undoped and Tl-doped Cs2BaBr4 crystals grown by the vertical Bridgman-Stockbarger method were investigated. The undoped sample showed scintillation with a broad peak from 300 to 600 nm and exhibited an emission peak similar to those observed in several alkali and alkaline earth halides. Meanwhile, the Tl-doped samples showed scintillation with two emission peaks at around 380 and 510 nm, and the origins of the emissions were considered to be 3P1→1S0 transitions of Tl+ ion and off-center self-trapped excitons localized near the Tl+ ion, respectively. The light yields of the undoped and 0.5% Tl-doped samples were estimated to be 2700 and 1700 ph/MeV with a typical error of ±10%, respectively. The improvement of Cs2BaBr4 crystal for light yield was not observed by doping of Tl. In the X-ray-induced afterglow properties, the 1% Tl-doped sample possessed the lowest afterglow level among the present samples, suggesting that Tl-doping improved the afterglow properties of Cs2BaBr4.