Traceable measurements of the activity concentration in air

Abstract

The nuclear reactions induced by high energetic protons in heavy targets such as UC 2 and ThC cause a particular, complex radiation protection task at facilities like ISOLDE: the measurement of a mixture of different isotopes of the radioactive noble gas radon and the radon progenies in air. The knowledge of their respective activity concentration is fundamental for exposure assessments.Due to the complex mixture of activity concentrations in air, its precise determination is quite difficult. Therefore, a new procedure for taking reference samples was developed and implemented for the traceable measurement of the activity concentration of radioactive ions (e.g. radon progenies) in air. This technique is combined by measuring α-particles with a multi-wire ionization chamber for the parallel on-line determination of the activity concentration of different radon isotopes.

Effect of air on gas amplification characteristics in argon–propane (1%)-based proportional counters for airborne radon monitoring

“…In fact, it is rather difficult to perform a spectroscopy in open air, due to the presence of oxygen, water vapor and other electronegative gas traces. Nevertheless, some research groups have already made significant progress in this direction [3][4][5][6][7][8][9] and some results are briefly reviewed below.…”

“…However, the device is still based on ion collection and, since the electrons are captured by electronegative gases, e.g., oxygen, only positive and negative ions are suitable for collection in pulses. This results in very low amplitude and long-current pulses of about 1 fA in 30 ms [8]. Therefore, this multi-wire pulse ionization chamber is naturally subjected to some limitations such as long collection times and residual microphonics noise.…”