WP2: High-energy (MV) photon beams between 4 MV and 20 MV, including flattening filter free beams (FFF).

The objectives of this work package are: (i) to measure kQ,Q0 factors for at least 8 types of ionisation chambers and a range of beam qualities, ensuring direct traceability of the kQ,Q0 factors to primary standards of absorbed dose to water; (ii) to calculate kQ,Q0 factors for these beams using several validated Monte Carlo codes; (iii) to compare the measured and calculated kQ,Q0 factors for high-energy (MV) photon beams, and to provide IAEA with a validated consistent new dataset of kQ,Q0 factors with target standard uncertainties better than 0.7 %.