Intercomparison of personal and ambient dosimeters in extremely high-dose-rate pulsed photon fields

Recent advances in laser driven accelerators boosted the development of high dose-rate fast pulsed systems all over the world. The stray radiation comprises primarily high-energy photons, resulting in extremely high dose rates within pico-/femto-second pulses. Dose measurements in such conditions have to be evaluated to validate methods. To tackle this challenge the EUropean RAdiation DOSimetry Group (EURADOS) started a program of dosimeters intercomparison, with a progressive approach, starting by a first evaluation in fields with μs pulse duration. The first comparison took place at the Lausanne University Hospital Center with an electron LINAC in Sept. 2017 involving 7 European institutes. Several passive and active dosimeters were tested with a tunable air kerma per pulse of the order of MGy/h. All instruments, except electrets, did not show any dose rate dependence, thus being selected as possible candidates for further studies.