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The effect of various dissolved gases on the heat defect of water
Author(s) -
Ross C. K.,
Klassen N. V.,
Smith G. D.
Publication year - 1984
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.595547
Subject(s) - calorimeter (particle physics) , calorimetry , oxygen , water vapor , radiolysis , hydrogen , irradiation , argon , chemistry , radiochemistry , impurity , nitrogen , analytical chemistry (journal) , absorbed dose , materials science , aqueous solution , thermodynamics , environmental chemistry , nuclear physics , physics , organic chemistry , detector , optics
Recent measurements of the absorbed dose to air‐saturated water, made using water calorimetry and assuming a zero heat defect for irradiated water, gave results 2%–5% higher than those determined by more conventional means. According to the current radiation chemical model for air‐saturated water, the dose measured by water calorimetry assuming a zero heat defect should actually be 2% too low because of the endothermicity of the radiolysis processes in water. In order to examine possible sources for this discrepancy, we have constructed a small calorimeter (holding 100 ml of water) with which to measure the temperature rise in irradiated water saturated with various gases. The gases used were air, oxygen, argon, nitrogen, and hydrogen/oxygen mixtures. Irradiations were carried out with 20‐MV x rays at a dose rate of 0.41 Gy/s. Our results are consistent with model calculations, except for some differences for accumulated doses of less than 100 Gy. The discrepancies we find at low doses and the discrepancies observed by others using water calorimeters may arise from impurities in the water.