Common menu bar links

Institutional links

Geological Survey of Canada

Radiation Geophysics

Glossary of gamma-ray spectrometry terms

General

AGRS: Airborne Gamma-Ray Spectrometry
NaI: Each of the 14 NaI detectors used in the GSC’s Airborne Gamma-Ray Spectrometry system is a single cylindrical crystal of Sodium Iodide (NaI), having a volume of approximately 3.5 L.
Operation Morning Light: Code name for the 1978 joint Canada-US operation to locate and recover debris from the Cosmos 954 nuclear-powered satellite that fell to earth on January 24, 1978.

Variables

K: potassium, i.e. K⁴⁰ (units: %)
eU: equivalent uranium concentration by weight (the spectrometer directly measures Bi²¹⁴, that is an indirect measure of uranium) (units: ppm)
eTh: equivalent thorium concentration by weight (the spectrometer directly measures Tl²⁰⁸, that is an indirect measure of thorium) (units: ppm)
Total Count: all counts from 400 to 3000 keV. (units: cps or uR/h)
Natural Exposure: computed from K (%), eU (ppm), eTh (ppm) concentrations:
Exposure = 1.505 K + 0.625 eU + 0.31 eTh (uR/h)
(Grasty et al, 1984) ’Exposure’ is different from the traditional ’Total Count’, in that it excludes radiation from man-made contaminants.
Natural Air Absorbed Dose Rate: computed from K (%), eU (ppm), eTh (ppm) concentrations:
Absorbed Dose Rate = 13.08 K + 5.43 eU + 2.69 eTh (nGy/h) ’Natural Air Absorbed Dose Rate’ is different from the traditional ’Total Count’, in that it excludes radiation from man-made contaminants.
eU/eTh, eU/K, eTh/K: ratios of K, eU, eTh that are useful for interpretation

Units

nT: unit of magnetic total field (nano Tesla)
ppm: unit of concentration by weight (part per million), used for eU (uranium) and eTh (thorium)
%: for potassium (K⁴⁰): unit of concentration by weight
for VLF: unit of signal strength
Ur: unit of radioelement concentration by weight
(1 Ur is defined as the total count rate from 1 ppm uranium in equilibrium)
µR/h: unit of Exposure (micro Roentgen/hour)
nGy/h: unit of Natural Air Absorbed Dose Rate (nano Gray/hour)

http://cgc.rncan.gc.ca/gamma/gloss_e.php