Project description:

Radon is a naturally occurring radioactive gas and one of the most common causes of lung cancer after smoking. It is colorless, odorless and tasteless and therefore cannot be perceived by the human senses. Radon is produced by the decay of naturally occurring radioactive substances in the ground. It quickly dilutes in the outside air and is not normally a problem there. However, radon can penetrate buildings and accumulate in the indoor air. Radiation protection legislation therefore regulates protection against radon in recreation rooms and workplaces. A reference value of 300 becquerels per cubic meter for the average annual radon-222 activity concentration in the air applies to indoor recreation rooms and indoor workplaces (Sections 124 and 126 of the Radiation Protection Act). 300 becquerels per cubic meter correspond to 300 radon decays per second and per cubic meter of indoor air. [1]

The importance and public focus on the comprehensive recording of radon concentrations in buildings has therefore increased significantly in recent years.

Direct measurement of the alpha particles produced during the decay of radon and its decay products is not trivial. For cumulative measurements, which record the average exposure over a period of weeks to several months, passive nuclear track measuring devices are used.

Active alpha detectors are used to record short-term changes in the radon concentration in the outside air or in nuclear laboratories. Ionization chambers also belong to this group of measuring devices. In principle, an ionization chamber consists of an electrically shielded container. Inside the container are measuring electrodes which are connected to a sensitive amplifier. Each alpha particle leaves a trail of ionized ions and electrons as it passes through the air. These are formed from the air. This charge can be collected and analyzed by an electric field between the electrodes.

These systems, also known as alpha-pulse ionization chambers (AIIK), enclose volumes of several liters and allow precise measurements and rapid measurements of the current radon concentration.

As part of the EU project RadonNET and in cooperation with the Physikalisch-Technische-Bundesanstalt in Braunschweig, an AIIK was developed and set up here at the institute. This allows radon concentrations below 10 Bq/m^3 to be measured.

• Radon project

• [1] https://www.bmuv.de/themen/strahlenschutz/ionisierende-strahlung/radon