external exposure facility Gammacell40 Exactor Paul Schofield ISS Rome acquired its Gammacell® 40 Exactor (Nordion International) in 1993 for acute gamma irradiation of biological samples; it forms part of the LIBIS facility complex and complements the Cs-137 low dose rate irradiator in the same room. The system delivers high dose rate gamma exposures and is used for comparative studies alongside the low dose rate LIBIS irradiator to investigate dose-rate effects on cellular responses. It is available for collaborative research through the local group. Located at Istituto Superiore di Sanità.