Migration to new ampoule types for the NPL secondary standard ionisation chambers

M Baker; A Fenwick; K Ferreira; J Keightley; L Johansson; S Collins

doi:10.1016/j.apradiso.2013.11.104

Migration to new ampoule types for the NPL secondary standard ionisation chambers

Appl Radiat Isot. 2014 May:87:224-8. doi: 10.1016/j.apradiso.2013.11.104. Epub 2013 Dec 3.

Authors

M Baker¹, A Fenwick¹, K Ferreira¹, J Keightley², L Johansson¹, S Collins¹

Affiliations

¹ National Physical Laboratory, Teddington, Middlesex TW110LW, UK.
² National Physical Laboratory, Teddington, Middlesex TW110LW, UK. Electronic address: john.keightley@npl.co.uk.

PMID: 24365464
DOI: 10.1016/j.apradiso.2013.11.104

Abstract

As the pre-calibrated sample containers used for activity assay in the two NPL secondary standards ionisation chambers are being phased out, suitable replacements have been identified. Characterisation checks have been carried out on the new ISO ampoules and a long-term recalibration schedule has been devised. Around 40 calibration factors have been determined so far and comparison of ion chamber responses for the two ampoule types showed variations of up to 7% for low energy photon emitting radionuclides.

Keywords: BS ampoules; Calibration factors; ISO ampoules; Ionisation chambers response.