The scintillation intensity and decay from Nd³⁺4f²5d and 4f³excited states in several fluoride crystals

Abstract

Nd3+-doped LaF3, LiYF4, CsY2F7, BaY2F8 and BaF2 crystals were investigated. For scintillator applications, the characteristics of the fast Nd3+ 4f25d to 4f3 emission component is of interest. The effective 4f25d to 4f3 scintillation decay time under gamma irradiation was found to vary from 5 to 42 ns, depending on the host lattice. Light yields were determined under X-ray excitation. The 4f25d to 4f3 output from many samples was seriously affected by impurity absorptions. After correcting for these, an estimate was made of the maximum possible 4f25d to 4f3 light yield to be expected in very pure Nd3+-doped crystals. In neither of the cases was a 4f25d to 4f3 light yield of more than about 1000 photons per MeV of X-ray energy found. In addition to Nd3+ 4f25d to 4f3 emission, Nd3+ 4f3 to 4f3 and host emissions were also recorded at wavelengths shorter than 550 nm. A semi-quantitative model is given for the Nd3+ 4f25d to 4f3, 4f3 to 4f3 and host emission intensities.