Absorbed dose — Science definition

Energy deposited per unit mass, measured in gray.

Where it is taught

In use

Activity measures decays per second; absorbed dose measures energy per mass in gray (J/kg).

Mass–Energy, Nuclear Reactions & Radiation Evidence

Questions using absorbed dose

Problem 1

A supplied reaction releases 0.0015 u of rest-mass equivalent per event. Estimate energy in MeV, then explain why a detector count rate cannot directly give absorbed dose.
Answer and explanation

Energy≈0.0015×931.5=1.397 MeV/event. Dose also needs energy deposited, exposed mass, radiation characteristics and geometry; count rate includes detector efficiency/background and is not dose.

Energy≈0.0015×931.5=1.397 MeV/event.

Dose also needs energy deposited, exposed mass, radiation characteristics and geometry; count rate includes detector efficiency/background and is not dose.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical or environmental mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 2

Independent chapter check: A supplied reaction releases0.0015 u of rest-mass equivalent per event. Estimate energy in MeV, then explain why a detector count rate cannot directly give absorbed dose.
Answer and explanation

Energy≈0.0015×931.5=1.397 MeV/event. Dose also needs energy deposited, exposed mass, radiation characteristics and geometry; count rate includes detector efficiency/background and is not dose.

Energy≈0.0015×931.5=1.397 MeV/event.

Dose also needs energy deposited, exposed mass, radiation characteristics and geometry; count rate includes detector efficiency/background and is not dose.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical or environmental mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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