EUROMET supplementary comparisons for photon and beta radiation--actual state and first results.

In January 2004, two EUROMET supplementary comparisons started, coordinated by Physikalisch-Technische Bundesanstalt (PTB): one for the radiation protection quantity 'personal dose equivalent' Hp(10) using X-radiation, and one for the quantity 'absorbed dose in tissue' Dt(0.07) using beta reference fields. The focus of both comparisons lies on calibrations using radiation qualities at which the dissemination of the quantities considered here is difficult. Within the scope of the two comparisons, an ionisation chamber shall be calibrated. Together with a transfer chamber optimised to measure Hp(10) and Dt(0.07), respectively, for each comparison a complete electronic measuring system is circulated. These transfer devices, as well as, a specially developed test procedure, which has to be carried out by each participant to check the instruments, are described. For both comparisons, the results of those participants who had finished their measurements and delivered the measuring protocol until February 2005 were evaluated. As the comparisons are still running these first results are shown in an anonymous form. A first assessment of the data will be given.