ANSI N42.14-1999 pdf download American National Standard for Calibration and Use of Germanium Spectrometers for the Measurement of Gamma-Ray Emission Rates of Radionuclides
3. Definitions
The word “shall” denotes a requirement, the word “should” denotes a recommendation, and the word “may” denotes permission. To conform to this standard, Ge spectrometry shall be performed in accordance with the requirements of this standard, but not necessarily with its recommendations; however, justification should be documented for deviations from a recommendation.
For the purposes of this standard, the following terms and definitions apply. IEEE Std 100-1996 should be referenced for terms not defined in this clause.
3.1 abundance: See: emission probability per decay [ P ( E ) or P γ ( E )].
3.2 activity (A): The expected number of spontaneous nuclear decays (transformations) in unit time from a specified energy state (excluding prompt decays from a lower nuclear level) for a given amount of a radionu- clide. Its standard unit (SI) is the becquerel (Bq), where one Bq equals one decay per second. Activity has often been expressed in curies (Ci), where 3.7 × 10 10 Bq equals 1 Ci, exactly.
3.3 ADC conversion gain: The number of channels over which the full amplitude span can be spread; usu- ally 2048–8192 channels are used for Ge gamma-ray spectrometry.
3.4 analog-to-digital converter (ADC): An electronic device used to convert the amplitude of a voltage pulse from analog to digital format.
3.5 attenuation: The net loss at the detector of primary photons of a given energy resulting from their inter- action with matter either due to the occurrence of scattering or absorption in the sample or in material between the sample and the detector crystal.
3.6 background: Spectral data including peaks not caused by the source but rather resulting from radioac- tive decay occurring in the surrounding environment or resulting from cosmic-ray interactions in or adjacent to the detector. See also: continuum.
3.7 baseline: See: continuum.
3.8 calibration: The determination of a value that converts a measured number into a desired physical quan- tity (e.g., pulse height into photon energy, or counts per second into emission rate).
3.9 cascade summing: See: coincidence summing of x and gamma rays.
3.10 cascade transitions: Gamma rays in the radioactive decay of a single atom that are emitted sequen- tially and within the resolving time of the spectrometer.
3.11 coincidence summing of x and gamma rays: The simultaneous detection of two or more photons originating from a single nuclear disintegration that results in only one observed (summed) pulse. Syn: cascade summing; true coincidence summing.