Scintillation properties of Nd~(3+), Tm~(3+), and Er~(3+) doped LuF_3 scintillators in the vacuum ultra violet region

摘要

In order to develop novel vacuum ultra violet (VUV) emitting scintillators, we grew Nd 0.5%, Tm 0.5%, and Er 0.5% doped LuF_3 scintillators by the μ-pulling down method, because LuF_3 has a very wide band gap and Nd~(3+), Tm~(3+) , and Er~(3+) luminescence centers show fast and intense 5d-4f emission in VUV region. Transmittance and X-ray induced radioluminescence were studied in these three samples using our original spectrometer made by Bunkou-Keiki company. In the VUV region, transmittance of 20-60% was achieved for all the samples. The emission peaks appeared at approximately 180,165, and 164 nm for Nd~(3+), Tm~(3+) , and Er~(3+) doped LuF_3, respectively. Using PMT R8778 (Hamamatsu), we measured their light yields under ~241Am ot-ray excitation. Compared with Nd:LaF_3 scintillator, which has 33 photoelectrons/5.5 MeV α, Nd:LuF_3 and Tm:LuF_3 showed 900 ± 90 and 170 ± 20 ph/5.5 MeV-α, respectively. Only for the Nd doped one, we can detect ~(137)Cs 662 keV γ-ray photoabsorption peak and the light yield of 1200±120 ph/MeV was measured. We also investigated their decay time profiles by picosecond pulse X-ray equipped streak camera, and the main decay component of Nd:LuF_3 turned out to be 7.63 ns.