Speaker
Description
The provision and dissemination of radioactivity standards within the UK is largely dependent on the suite of ionisation chambers maintained at the NPL. These chambers are vital for underpinning work in the medical, industrial, low level and nuclear data fields. The NPL provides ongoing support for the commercially available secondary standard radionuclide calibrator (SSRC), currently marketed as the Fidelis, and previously available as the Vinten 671/271, ISOCAL IV or NPL-CRC. This system is based on the NPL designed IG-42 chamber which is marketed and constructed by Centronic Ltd. Several monte-carlo models have been developed for this system by the international community to allow estimation of dial settings for novel geometries and radionuclides. This ionisation chamber is used throughout the world both by industry and national metrology institutes (or designated institutes) to demonstrate traceability to NPL and the international community. The NPL also maintains a fleet of other commercially available radionuclide calibrators to provide indicative dial settings during standardisations of novel radionuclides and to investigate measurement problems that may be encountered in the clinical environment.
The design and material composition details of the NPL SSRC are presented to support those developing Monte Carlo models. A brief discussion regarding common pitfalls and advice on developing a Monte Carlo model has been included. A detailed description of the production methodology and comparison measurements to the master chamber at the NPL is presented. A description of common geometries used including material composition and designs for dedicated holders is introduced. An updated list of calibration factors for the NPL SSRC and dial settings for the NPL maintained Capintec and Atomlab radionuclide calibrators are included in the publication.
