1 m3 radon chamber
Since 2001, a System for Test Atmospheres with Radon (STAR) is operative to calibrate measuring instruments. The radon chamber has been developed following the norm IEC 61577:2000 “Radiation protection instrumentation – Radon and radon decay product measuring instruments”.
Radon chamber structure
The Radon chamber has been built on the bases of a glove box with the following dimensions: (126x75x87) cm3, hence it has a volume of 0,8 m3. Walls are made of polycarbonate and they are 8mm thick, the floor is made of stainless steel.
On one smaller wall, there is a double air lock system (SAS) to allow the insertion of the devices to calibrate. In addition, some watertight passages allow to bring into the chamber the supply voltage and the data transfer line for the remote instrument control.
Two fans are located in the chamber to ensure the radon concentration homogeneity in the volume. Radon is sucked from a Ra-226 source: a vial containing a patented epoxy plastic foil with emanation power approaching 1. Radon is then inserted in the chamber by a volumetric dosage system.
Measure reference instrument
The reference instrument, guaranteeing the metrological traceability, is an ionization chamber AlphaGUARD PQ2000. It is calibrated every two years in European institutes that have the ISO 17025 certification.
Measurement range
The possible concentrations and exposures obtainable in the chamber are shown in the following table:
| Measure parameter | Measurement range |
| Concentration | 1 000 ÷ 20 000 Bq m-3 |
| Exposure | 200 ÷ 10 000 kBq h m-3 |
Thanks to the large volume of the chamber, it is possible to carry out more calibrations simultaneously (depending on the instrument dimensions) and to locate a high number of passive devices (around 60).
2 m3 radon chamber
From 2016, a second STAR is operative for the instrument calibrations in radon controlled atmospheres. The chamber has been developed following the norm IEC 61577, with some operating and radiation protection improvements from the first one. Thi is the accreditated chamber (see this page).
Radon chamber structure
The new chamber has been built on the bases of a glove box with the following dimensions: (150x110x120) cm3, hence it has a volume of 1,89 m3. The two bigger walls are made of polycarbonate and they are 15 mm thick, the others are made of stainless steel.
On one smaller wall, there is a double air lock system (SAS) to allow the insertion of the devices to calibrate. In addition, some watertight passages allow to bring the supply voltage and into the glove box.
Some fans are located in the chamber to ensure the radon concentration homogeneity in the whole volume. Radon is sucked from a Ra-226 source: a vial containing a patented epoxy plastic foil with emanation power approaching 1. Radon is then inserted in the chamber by a volumetric dosage system.
This chamber is highly automatized and monitored in all the environmental parameters.
Measure reference instrument
The reference instrument, guaranteeing the metrological traceability, is an ionization chamber AlphaGUARD DF2000 that can be connected to the AlphaPM Radon Progeny Meter for the determination of the Radon progeny concentration in air.
It is calibrated every two years in European institutes that have the ISO 17025 certification.
Alpha Guard DF2000 
Alpha PM Radon Progeny Meter
Measurement range
The possible concentrations and exposures obtainable in the chamber are shown in the following table:
| Measure parameter | Measurement range |
| Concentration | 1 000 ÷ 12 000 Bq m-3 |
| Exposure | 200 ÷ 4 000 kBq h m-3 |
Thanks to the large volume of the chamber, it is possible to carry out more calibrations simultaneously (up to 10 instruments) and to locate a high number of passive devices (depending on the device type, the number changes).
Information and contacts
For information about the radon chambers and our activities, please do not hesitate to contact us by email to the following address: metrologia-radiazioni@polimi.it