Fluoride crystal, scintillator for detection of radioactive ray, and radioactive ray detector

[Problem] To provide :a novel scintillator which can be combined suitably with a vacuum ultraviolet light receiver element having high radiation resistance; and a fluoride crystal in which both cross-luminescence and electronic transition emission of a rare earth can be achieved simultaneously and which can be used as a scintillator-equipped radioactive ray detector for the discrimination between a neutron ray and a γ-ray. [Solution] A fluoride crystal comprising KLiLuF 5 containing at least one rare earth element; a scintillator for detecting an radioactive ray, which comprises the fluoride crystal; and a radioactive ray detector characterized by using the scintillator.