Definitions in this glossary are meant for facilitating the use of the ANGLE 5 User Guide, often simplified, and may vary from the exact meanings
absolute method – quantification based on calculations only, implying physical parameters which characterize the detection process
absorbing layers – all absorbing materials between the source and the detector (including air)
amplifier – piece of electronics further amplifying the signal from a preamplifier
antimicrophonic shield – in some detectors, thin layer of low-Z material between the end-cap and the crystal, aimed at absorbing noise (mechanical vibrations) which disturbs the spectrum at low energies
attenuation – decrease in the intensity of a photon beam due to interaction with matter
calculation parameters – in Angle, this data is needed for an efficiency calculation to be performed, including those for: detector, radioactive source and its container, counting geometry, gamma-energies of interest, reference efficiency curve and calculation precision
calibration source – source with certified (specific) activities of the radionuclides present
cascade summing – for some radionuclides, the effect of removal or pile up of counts in a full energy peak in the spectrum, due to simultaneous/cascade emission of photons in the decay schemes
coating layer – thin protective layer coating/lining the detector end-cap or source container
container foot – on some source containers, a small separation between the container bottom and the ground
counting arrangement – ensemble of the detector, source, container, holder and absorbing layers
counting geometry – see geometry
detection efficiency – characteristic of the counting arrangement (the ensemble of the detector, source, container, including their geometrical positioning, and all absorbing layers): probability that a photon emitted from the sample will be detected/recorded by the detector
detector – device for radiation detection
detector bulletization – rounding of the detector crystal edges in order to smooth out the electric field in the crystal, enabling better charge collection
detector calibration – experimental determination of the detection efficiency using calibration source(s)
detector contact – electric contacts (electrodes) placed at the detector crystal, creating electric field therein; one of the contacts is normally the detector dead layer itself, the other may be, for example, a thin metal layer
detector crystal – active part of the detector, placed under high voltage and giving out the initial pulse from the energy deposited by the incoming photon
detector dead layer – inactive part of the detector crystal, usually at its surface
detector efficiency – characteristic of detector: detection efficiency at 1332 keV (Co-60 point source at 25 cm distance) as compared to 3 × 3" NaI detector (thus expressed in %); also called relative efficiency
detector end-cap – outer (visible) cap around the detector crystal, vacuum sealed
detector housing – inner physical support for the detector crystal
effective solid angle – compound parameter, closely related to detection efficiency, combining geometrical solid angle, attenuation effects and detection effects; the ratio between effective solid angle and total efficiency is 4 π
emission probability – probability that an atomic nucleus will emit radiation (e.g. gamma-ray) in unit time,
end-cap window – a portion at the top of the detector end-cap, which is made of lower Z material than the end-cap itself (e.g. beryllium or carbon fiber, while the end-cap is usually made of aluminium or magnesium)
full-energy peak – part of the spectrum around characteristic gamma-energy for the given radionuclide
full-energy peak efficiency – see peak efficiency
gamma-rays – photons emitted from atomic nucleus; gamma-energies range (at the low end) partially overlaps with X-rays range (at the high end)
gamma-spectrometry – quantitative determination of radionuclides present in the sample
gamma-spectroscopy – qualitative determination of radionuclides present in the sample
gamma-spectrum – result of spectroscopic measurement, distribution of recorded counts vs gamma-energies
GammaVision/Maestro – ORTEC’s spectroscopy software
Gauss coefficient – number of integration segments in the Gauss-Legendre numerical integration method; higher coefficient yields better calculation precision, but slower calculations
Genie 2000 (Genie 2K) – Canberra’s spectroscopy software
geometry (counting geometry) – in Angle this denotes the position of the source vs. the detector, including source holder and absorbing layers
holder (source support) – something that keeps the source at certain position vs the detector during counting
intercepting layers – see absorbing layers
Marinelli container (beaker) – source container in a form which enables the source to be closely positioned around the detector, yielding high detection efficiency
Monte Carlo method – computational algorithms that rely on repeated random sampling to obtain numerical results
multichannel analyzer – piece of electronics where signals are sorted according to their intensity, which is proportional to the photon energy deposited in the crystal
peak area – net number of counts in the peak (i.e. with spectrum background subtracted)
peak efficiency – detection efficiency, taking into account only full deposition of photon energy in the detector
photon – the quantum of electromagnetic radiation, having the properties of both the particles and waves (including gamma and X-rays)
preamplifier – piece of electronics which performs initial amplification of the signal/charge obtained from the photon
quantification – step from qualitative to quantitative results
quasi-relative method – a semi-empirical method in which counting arrangements for the sample and the source are not exactly the same (as is the case for the relative method), but the difference is not great
radioactivity – spontaneous, probability-related (stochastic), transformation of atomic nucleus, followed by the emission of radiation (e.g. in the form of alpha, beta or gamma-rays)
radionuclide – atomic nucleus which is radioactive
reference efficiency curve – result of detector calibration, detection efficiency vs energy for the given counting arrangement and calibration source(s), in Angle, serves as a reference parameter for calculated efficiencies
relative method – quantification based on standards (sources with a known activity)
sample – source of unknown activity (which is to be determined)
scintillation detector – device for photon detection, having a scintillator crystal (usually NaI) as an active body
self-attenuation – attenuation of photon beams within the source itself
self-standing source – solid source (e.g. in the form of a pill) which can stand on the holder on its own (i.e. without a container)
semiconductor detector – device for photon detection, having a semiconductor crystal as an active body, usually high-purity germanium (HPGe)
semi-empirical method – quantification based partly on standards, partly on calculations
source – radioactive material
specific activity – activity per mass unit
spectrometer – a device used to register and analyze gamma-rays emitted from the source in a specific range of energies; gamma-energies range (its low end) partially overlaps with X-rays range (its high end), roughly at 20 – 100 keV
spectrometry – see gamma-spectrometry
spectroscopy – see gamma-spectroscopy
standard – source with known/certified activity, usually from a specialized manufacturer
total efficiency – detection efficiency, taking into account any (full or partial) deposition of photon energy in the detector; the ratio between effective solid angle and total efficiency is 4 π
true coincidence summing – see cascade summing
vacuum (detector vacuum) – vacuum space between the crystal and end-cap
X-rays – photons emitted from atomic electron shell; range of X-rays (its high end) partially overlaps with range of gamma-energies (its low end), roughly at 20 – 100 keV
Semiconductor and scintillation detector gamma-efficiency calculations