O. Guillot-Noel, J. C. van't Spijker, J. T. M. de Haas, P. Dorenbos, C. W. E. van Eijk, K. W. Krämer and H. U. Güdel
Scintillator Properties of RbGd₂Br₇:Ce. Advantages and Limitations.
IEEE Trans. Nucl. Sci. 46 (5), (1999)                 

Abstract: The scintillation properties of RbGd₂Br₇ crystals, doped with Ce³⁺ concentrations of 0.02, 0.11, 0.88, 2.05, 4.1, and 9.8%, are studied under X-ray and g-quanta excitations. For the RbGd₂Br₇ sample doped with 9.8% Ce, the authors measured a light yield of 56000 ± 6000 photons per MeV of absorbed g-ray energy with a main decay time of 43 ± 1 ns, using a Hamamatsu R1791 photomultiplier (PMT), a ¹³⁷Cs radioactive source, and a shaping time of 10 ms. A time resolution of 790 ± 10 ps was measured for the RbGd₂Br₇:9.8% Ce compound, using Baf₂ as second scintillator, two XP2020Q PMT's, a ²²Na source, and an energy threshold set at E 511 keV. With the R1791 PMT, an energy resolution of 4.1% (FWHM over peak position) for the 662-keV full absorption peak has been observed for two crystals of 7 × 4 × 2 mm³ and 15 × 5 × 1 mm³ with 4.1 and 9.8% Ce content, respectively. Moreover, the non-proportional response of three RbGd₂Br₇:Ce compounds with different concentrations (0.11, 2.05, and 9.8%) were studied revealing an almost-constant light output response from 17.4 keV to 1 MeV. These properties are compared to three other well-known scintillators: NaI:Tl, CsI:Tl, and Lu₂SiO₅:Ce.