Australian primary standards

ARPANSA maintains the primary standards for the dosimetry of ionisation radiation for Australia.

The standards are maintained under an authorisation from the National Measurement Institute under the National Measurement Act.

As a part of the authorisation, ARPANSA participates in international comparisons and international metrology organisations. ARPANSA's Calibration and Measurement Capabilities (CMCs) and comparison results are listed in the Key Comparison Database (KCDB).

The primary standards are all detectors of radiation. For megavoltage radiation ARPANSA maintains a graphite calorimeter. For kilovoltage radiation, ARPANSA has two free air chambers. At 60Co a standard ionisation chamber is also maintained for determination of air kerma.

A graphite calorimeter is used at the primary standard for absorbed dose in megavoltage beams.

We use a graphite cavity chamber to determine air kerma at Cobalt-60.

A smaller version of the MEFAC, the LEFAC is optimised for measurements in the range 10 - 70 kVp.

The MEFAC free air chamber is a standard of exposure, and is used as a standard of air kerma by using the energy required to create an ion par in air: 33.97 J/C.