THE SCINTILLATION INTENSITY AND DECAY FROM ND3-STATES IN SEVERAL FLUORIDE-CRYSTALS( 4F(2)5D AND 4F(3) EXCITED)

Nd3+-doped LaF3, LiYF4, CsY2F7, BaY2F8 and BaF2 crystals were investig ated. For scintillator applications, the characteristics of the fast N d3+ 4f(2)5d --> 4f(3) emission component is of interest. The effective 4f(2)5d --> 4f(3) scintillation decay time under gamma irradiation wa s found to vary from 5 to 42 ns, depending on the host tattice. Light yields were determined under x-ray excitation. The 4f(2)5d --> 4f(3) o utput from many samples was seriously affected by impurity absorptions . After correcting for these, an estimate was made of the maximum poss ible 4f(2)5d --> 4f(3) light yield to be expected in very pure Nd3+-do ped crystals. In neither of the cases was a 4f(2)5d --> 4f(3) light yi eld of more than about 1000 photons per MeV of x-ray energy found. In addition to Nd3+ 4f(2)5d --> 4f(3) emission, Nd3+ 4f(3) --> 4f(3) and host emissions were also recorded at wavelengths shorter than 550 nm. A semiquantitative model is giuen for the Nd3+ 4f(2)5d --> 4f(3), 4f(3 ) --> 4f(3) and host emission intensities.