Why is calorimetry used in physics


calorimeter, 1)Thermodynamics: Apparatus used in calorimetry to measure heat effects that occur in physical, chemical or biological processes. When designing the calorimeter must be good Thermal insulation and ensure that there is good heat exchange within the calorimeter (e.g. using stirrers). Depending on the problem, you can use different types of calorimeters: Liquid or mixed calorimeters measure the energy supplied or removed from a certain volume of liquid from the temperature change of the liquid and the specific heat capacity. At Metal calorimeters Instead of the liquid, a thick-walled container made of copper or silver is used to prevent the dissipation of heat to the environment as much as possible (e.g. using a Dewar vessel). in the adiabatic calorimeter heat loss is prevented by keeping the surrounding medium at the same temperature as the calorimeter vessel and in the isothermal calorimeter or. Compensation calorimeter the amount of heat to be measured is precisely compensated by an externally supplied, measurable amount of heat, so that the temperature remains constant. Other calorimeters are the calorimetric bomb or gas calorimeter (Junkers calorimeter).

2)High energy physics: Device for determining the energy of particles. One distinguishes between electromagnetic and hadronic Calorimeters. In electromagnetic calorimeters, electrons or photons generate a particle cascade (a shower) through bremsstrahlung and pair generation, and part of the particle energy can be detected in the form of Cherenkov radiation, scintillation light or ionization. This contribution is proportional to the primary energy of the particle. In order for the shower to be completely absorbed, the calorimeter must extend over several radiation lengths. The characteristic size of hadronic calorimeters is the nuclearAbsorption length. Since it is greater than the radiation length, hadronic calorimeters are usually much more massive than electromagnetic ones. The energy resolution is much worse; The fact that up to 20% of the hadronic energy is used to break the nuclear bonds contributes to the reduction of the detectable energy.

Calorimeter: Stirring calorimeter as an example of a metal calorimeter. 1: stirrer, 2: thermometer, 3: double-walled Dewar vessel, 4: base.