The counting efficiency is the ratio between the number of particles or photons counted with a radiation counter and the number of particles or photons of the same type and energy emitted by the radiation source. Counting efficiency varies for different isotopes, sample compositions and scintillation counters. Poor counting efficiency can be caused by an extremely low energy to light conversion rate, (scintillation efficiency) which, even optimally, will be a small value. It has been calculated that only some 4% of the energy from a β emission event is converted to light by even the most efficient scintillation cocktails.
- IUPAC Compendium of Chemical Terminology (2nd ed.). 1997.
- "Counting efficiency and quenching". National Diagnostics. 2011. Retrieved April 6, 2013.
|Photon energy||n||1||count of photons n with energy Qp = h⋅c / λ.[nb 2]|
|Photon flux||Φq||count per second||s−1||T−1||photons per unit time, dn/dt with n = photon number.
also called photon power.
|Photon intensity||I||count per steradian per second||sr−1⋅s−1||T−1||dn/dω|
|Photon radiance||Lq||count per square metre per steradian per second||m−2⋅sr−1⋅s−1||L−2⋅T−1||d2n/(dA cos(θ) dω)|
|Photon irradiance||Eq||count per square metre per second||m−2⋅s−1||L−2⋅T−1||dn/dA|
|Photon exitance||M||count per square metre per second||m−2⋅s−1||L−2⋅T−1||dn/dA|
|See also: Photon counting · SI · Radiometry · Photometry|