P. Dorenbos, J. C. van't Spijker, O. W. V. Frijns, C. W. E. van Eijk, K. Krämer, H. U. Güdel and A. Ellens
Scintillation properties of RbGd₂Br₇: Ce³⁺ crystals; fast, efficient, and high density scintillators
Nucl. Instr. Methods Phys. Res. B 132, 728-731 (1997)                 

Abstract: The scintillation properties of RbGd₂Br₇ crystal (r 4.7 g/cm³) doped with Ce³⁺ concentrations of 1 and 5 mol% studied under X-ray and g-quanta excitation are presented and compared with the properties of NaI(Tl) and other scintillators. For a sample doped with 5 mol% Ce, a light yield of about 55000 photons/MeV with a main decay time of 60 ns was measured. With a photomultiplier tube, an energy resolution of 3.8% (FWHM) for the 662 keV full absorption peak has been observed.