Comparison of calibration results for an extrapolation chamber obtained with different 90Sr+90Y secondary standard sources

Two secondary standard systems of beta radiation were used to calibrate a PTW extrapolation chamber Model 23391. Three 90Sr+90Y sources of different activities were used in this calibration procedure. Medium-term stability of the response of the chamber was also studied. The calibration was performed with and without field-flattening filters. The relative standard deviation of the obtained calibration factors was 8.3% for the aluminum collecting electrode and 4.1% for the graphite collecting electrode.

► 90Sr+90Y standard sources were used to calibrate a PTW extrapolation chamber. ► Characterization tests of the chamber response were performed. ► Chamber response showed very good short- and medium-term stabilities. ► Linear extrapolation curves were obtained. ► Calibration factors of the chamber were acceptable.