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A status report on the NPL water calorimeter.

Williams, A J; Rosser, K E (1998) A status report on the NPL water calorimeter. NPL Report. CIRM 22

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Abstract

At present, the primary standard at NPL for the measurement of absorbed dose in high energy photon beams is a graphite calorimeter. However, the quantity of interest in radiation dosimetry is absorbed dose to water. Therefore, a new absorbed dose to water standard based on water calorimetry has been developed for use in high energy photon and electron beams. The calorimeter operates at 4 °C, with temperature control being provided by a combination of liquid and air cooling. The sealed glass inner vessel of the calorimeter has been designed to minimise the effect of non-water materials on the measurement of absorbed dose. In particular, great care was taken in the design and construction of the temperature sensing thermistor probes so that glass is the only material in contact with high purity water inside the vessel. Measurements of absorbed dose to water made in 6, 10, and 19 MV photons, and 16 MeV electrons agreed, within the measurement uncertainties, with those determined by graphite calorimetry. Initial tests have confirmed the feasibility of the calorimeter design although further work is required before the calorimeter can be used as a primary standard.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CIRM 22
Subjects: Ionising Radiation
Ionising Radiation > Dosimetry
Last Modified: 10 Sep 2018 14:32
URI: http://eprintspublications.npl.co.uk/id/eprint/1039

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