The efficiency of 4 inch thick bismuth germanate and sodium iodide scintillators was measured for 75 MeV neutrons. The activation of the same detectors to fast neutrons is also reported.
Bol, A., Leleux, P., Lipnik, P., Macq, P., & Ninane, A. (1982). Sensitivity of BGO and NaI(Tl) scintillators to fast neutrons. Nuclear Instruments and Methods in Physics Research, 202(3), 511-512. https://doi.org/10.1016/0167-5087(82)90549-X (Original work published 1982)