Duane, S; Nutbrown, R F; Shipley, D R (2009) Changes to the NPL air kerma standard for 137Cs and 60Co. NPL Report. IR 17

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Abstract

The NPL maintains a primary standard of air kerma defined as the mean corrected response of three cavity ionisation chambers, which were designed to operate in 2 MV X-rays at therapy-level air kerma rates. The therapy level exposure calibration service for 2 MV X-rays was first instituted at the NPL in 1956; a chamber correction factor F was applied to the mean response of the standard cavity chambers. This factor was revised in 1969 and again in 1992 for 1 MV and 2 MV X-rays and for 137Cs and 60Co gamma-rays. This report documents the changes to the correction factors and presents new work re-evaluating the chamber correction factors for 137Cs and 60Co gamma-rays.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	IR 17
Keywords:	cavity, primary standard, chambers, air kerma, exposure
Subjects:	Ionising Radiation Ionising Radiation > Dosimetry
Last Modified:	02 Feb 2018 13:15
URI:	https://eprintspublications.npl.co.uk/id/eprint/4377