Abstract The response of Al 2 O 3 :C optically stimulated luminescence detectors (OSLDs) was investigated in a 250 MeV pencil proton beam. OSLD mapped for wide range average dose rates up to 9000 Gy s ?1 , corresponding ?150 kGy instantaneous rate each pulse. Two setups ultra-high (FLASH) experiments are presented, which enable OSLDs or biological samples be irradiated either water-filled vials...