Abstract: In this paper, a secondary standard ionization chamber for β radiation personal dose equivalent H_p(3) is developed. Different from the extrapolation structure design of the primary standard extrapolation ionization chamber, the secondary standard ionization chamber adopts the structure of a flat plate ionization chamber with a phantom, and takes into account high measurement accuracy (relative inherent error <2.0%) while greatly simplifying the complexity of the test process. The radiation performance test results show that relative inherent error within the individual dose equivalent rate of beta radiation H_p(3) from 5 mSv/h to 170 mSv/h does not exceed ±1.5%; with regard to beta radiation H_p(3), for measurement range of at least 5 orders within the personal dose equivalent rate of 0.5 mSv/h-1.5 Sv/h, the relative inherent error does not exceed ±4.0%; the relative deviation of the response under the incident angle of β radiation ±60° does not exceed ±5%; measurement repeatability of the ionization chamber is 0.6%; relative expanded uncertainty of the measurement with flattening filter at 30 cm for the ⁹⁰Sr/⁹⁰Y source is U_rel=3.9% (k=2). In addition, it was found experimentally that the H_p(3) ionization chamber has a relatively high response to low-energy contamination photons.

Key words: beta radiation, secondary standard ionization chamber for personal dose equivalent H_p(3), relative inherent error, angular response, uncertainty