Luminescence and scintillation properties of TlCdCl3:Sb crystals

Abstract An ideal scintillator for X- and gamma-ray detection should have a high light yield and a high effective atomic number ( Z eff ). In this study, we developed undoped TlCdCl 3 crystals and TlCdCl 3 :Sb (Sb: 0.5, 1.0 and 1.5 mol%) crystals with high Z eff (TlCdCl 3 :68.7), as candidate scintillators. The crystals were grown using the self-seeding solidification method, and their photoluminescence (PL) and scintillation properties were investigated. For the undoped TlCdCl 3 crystals, emission peaks were observed at 460 nm and 485 nm in the PL and X-ray-induced radioluminescence (XRL) spectra, respectively. For the TlCdCl 3 :Sb crystals, the PL spectra showed emission peaks at 480, 480 and 500 nm, while the XRL spectra exhibited peaks at approximately 510 nm. The emission bands of the TlCdCl 3 :Sb crystals were shifted to longer wavelengths than those of the undoped TlCdCl 3 crystals. The scintillation decay time constants for the undoped TlCdCl 3 crystals were 51 and 2613 ns, whereas for the TlCdCl 3 :Sb crystals, they were in the range of 65–81 and 4550–7350 ns. These results suggest that the incorporation of Sb 3+ ions induces long components of several thousand nanoseconds. The redshift and appearance of these long components indicate that Sb 3+ ions act as new luminescence centers in the undoped TlCdCl 3 crystal. The scintillation light yield of the TlCdCl 3 :Sb 1.0 mol% crystal was measured at 10,300 photons/MeV. The doping of Sb 3+ ions into the TlCdCl 3 lattice improved the scintillation light yield by up to four times compared to the undoped TlCdCl 3 crystal.