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Carl K. Ross is a physicist associated with ionizing radiation standards and water calorimetry. His 1997 paper with Norman V. Klassen identifies both authors with the ionizing-radiation standards laboratory in Ottawa and examines a fundamental problem in radiation dosimetry: deposited energy and measured heat need not be equal when irradiation also produces chemical reactions.^[ref]

Their analysis expresses the heat defect aswhere $E_a$ is absorbed energy, $E_h$ is the energy appearing as heat, $D_w$ is absorbed dose, and $c_w$ is the specific heat capacity of water. The temperature rise $\Delta T$ supplies a measurable thermal signal, while the heat defect accounts for the energy balance associated with radiolysis.^[ref]

For a hypothetical example, suppose the measured thermal quantity is $c_w\Delta T=0.98\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}$ and the heat defect is $0.02$. The corrected absorbed dose is then $0.98/(1-0.02)=1\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}=1\mathrm{Gy}$. The illustrative $2\%$ correction is chosen for arithmetic, rather than quoted as an experimental result. A positive heat defect means that some absorbed energy does not appear as heat; a negative value means that the measured heat exceeds the absorbed energy, with the difference supplied by the accompanying chemical reactions.

Ross and Norman V. Klassen later published a correction to an input reaction rate constant in their computer simulation. Their 2002 paper provides an explicit example of revising a physical measurement model when a supporting parameter changes.^[ref]

The heat defect in water calorimetry measures the fraction of absorbed energy that does not appear as heat because of radiation-induced chemical changes. Writing absorbed energy as $E_a$ and the energy appearing as heat as $E_h$, the convention used by Norman V. Klassen and Carl K. Ross isA positive value means less heat than the absorbed-energy equivalent; a negative value means the chemical response adds heat.^[ref]

If other thermal corrections are treated separately, the absorbed dose isAn illustrative $k_{\mathrm{HD}}=0.02$ means that $c_w\Delta T$ represents 98% of the dose, so the chemical correction multiplies that thermal estimate by $1/0.98$. The example fixes a sign convention; it is not a measured universal value for water.

The motivating evidence included variations with dissolved gases and comparison of radiolysis calculations with chemical measurements of hydrogen peroxide. Those tests address chemical energy accounting. An external heat leak or a drifting thermometer can also alter a temperature reading, but belongs to a different correction mechanism.^[ref]