Photon emission from 511 keV gamma rays incident on BaF2 and LaF3:Nd3+ crystals using a cesium iodide photocathode detector

We have studied the possibility of using BaF2 and LaF3 doped with Nd3+, concentrations ranging from 0.1 to 15 mol% as efficient converters of 511 keV gamma rays. We have measured the number of photoelectrons/MeV for both crystals using a parallel-plate avalanche chamber operating with a CsI photocathode. The photocathode is sensitive to wavelengths in the range 160–220 nm. The fast component of the BaF2 emission spectrum has peaks at roughly 175, 195 and 200 nm, and the LaF3:Nd3+ emission spectrum peaks at 173 nm. We measure 3.71 ± 0.04 ± 1.11 photoelectrons/MeV for the BaF2 and 4.81 ± 0.04 ± 1.44 photoelectrons/MeV for the LaF3:Nd3−. The results for BaF2 and LaF3:Nd3+ are consistent with measured scintillation properties of these crystals and CsI photocathode quantum efficiencies.