Water calorimetry
= Water calorimetry
\b[Water calorimetry] measures an energy transfer using the thermal response of <water>. In radiation metrology, it determines <absorbed dose> to water from a small measured temperature rise. The ideal conversion follows from $Q=mc_w\Delta T$ and $D=Q/m$:
$$
D=c_w\Delta T,
$$
where $c_w$ is water's <specific heat capacity>. The sample mass cancels because dose is energy per unit mass.<An Absorbed Dose Water Calorimeter: Theory, Design, and Performance by Steve R. Domen>[Abstract and opening description: calibrated thermistors and temperature-rise dose measurement.]{ref}
For an original scale estimate, take $c_w=4180\,\mathrm{J\,kg^{-1}\,K^{-1}}$ as an illustrative near-room-temperature value. An <absorbed dose> of $1\,\mathrm{Gy}=1\,\mathrm{J\,kg^{-1}}$ would then give only $1/4180\,\mathrm K$, about $0.239\,\mathrm{mK}$. Detecting such a small change requires careful thermometry and separation from background thermal drift.
The physical conversion also has chemical assumptions. <Heat defect> describes the fraction of absorbed energy that does not appear as heat because of radiation-induced chemical change. <Thermal conduction>, <convection> and sensor effects are additional measurement questions, rather than alternate names for that chemical correction. This makes <water calorimetry> an example of an apparently direct energy measurement whose interpretation still needs a well-defined model.