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[en] This paper describes how primary potassium, uranium and thorium standards can be prepared from potassium carbonate, radium chloride and from a thorium salt, manufactured in 1906, which has now reached radioactive equilibrium. Experiments utilizing prepared potassium and thorium samples of different density show how the calibrated constants derived from the primary standards can be modified to allow samples of different densities to be measured reliably
Source
Nuclear Energy Agency, 75 - Paris (France); 979 p; ISBN 92-64-02350-X; 
; 1982; p. 699-712; OECD; Paris (France); Symposium on uranium exploration methods; Paris (France); 1-4 Jun 1982
; 1982; p. 699-712; OECD; Paris (France); Symposium on uranium exploration methods; Paris (France); 1-4 Jun 1982
[en] Laboratory gamma-ray analyses of potassium, and gamma-equivalent uranium and thorium require accurately known reference standards for calibration. Because of uncertainty in the state of radiometric equilibrium in the uranium and thorium decay chains, reference standards analysed only for uranium and thorium are generally unsuitable. Equivalent uranium standards which have been analysed for radium-226 are reviewed. For equivalent thorium calibration, silicate, rocks with known thorium are adequate. The use of standards spiked with either radium-226 or old thorium salts has been suggested and would appear to offer significant advantages over the available natural matrix standards. The outsdanding question is whether individual laboratories should prepare their own standards or a central supply be established
Source
Nuclear Energy Agency, 75 - Paris (France); 979 p; ISBN 92-64-02350-X; ; 1982; p. 687-698; OECD; Paris (France); Symposium on uranium exploration methods; Paris (France); 1-4 Jun 1982
; 1982; p. 687-698; OECD; Paris (France); Symposium on uranium exploration methods; Paris (France); 1-4 Jun 1982
[en] Gamma-ray logging probes are calibrated in model boreholes which consist of a concrete sandwich containing a central ''ore zone'' and upper and lower ''barren zones''. Unexplained discrepancies have been reported for probes calibrated in model boreholes at Ottawa, Canada; Grand Junction, U.S.A.; and Adelaide, Australia. Intercalibration measurements were made at the three locations using the R and D logging system of the Geological Survey of Canada (G.S.C.) which provides full spectral recording on magnetic tape. The method of full spectral recording made it possible to select, after-the-fact, any desired energy windows in the spectrum and to produce new gamma-ray spectral logs from the re-windowed data. Thus the presence of thorium could be detected and measured and the Z-effect could be taken into account for each model. Fully corrected count-rates within the ore zones and areas under the log curve were determined for every run of every probe in every model for every window. From this information accurate ratios of uranium concentrations in the model holes in different countries were calculated (i.e. relative values). However, absolute uranium grades cannot be assigned until the ''true'' uranium content of any one of the models is determined
Source
Nuclear Energy Agency, 75 - Paris (France); 979 p; ISBN 92-64-02350-X; ; 1982; p. 715-728; OECD; Paris (France); Symposium on uranium exploration methods; Paris (France); 1-4 Jun 1982
; 1982; p. 715-728; OECD; Paris (France); Symposium on uranium exploration methods; Paris (France); 1-4 Jun 1982
[en] The activity assay of a radiopharmaceutical administration to a patient is normally achieved via the use of a radionuclide calibrator. Because of the different geometries and elemental compositions between plastic syringes and glass vials, the calibration factors for syringes may well be significantly different from those for the glass containers. The magnitude of these differences depends on the energies of the emitted photons. For some radionuclides variations have been observed of 70 %, it is therefore important to recalibrate for syringes or use syringe calibration factors. Calibration factors and volume correction factors have been derived for the NPL secondary standard radionuclide calibrator, for a variety of commonly used syringes and needles, for the most commonly used medical radionuclide. (author)
Source
NPL report; (no.CIRM56); 2002; 58 p; ISSN 1369-6793; ; Available from British Library Document Supply Centre- DSC:6029. 28071(56); Country of input: International Atomic Energy Agency (IAEA); Includes bibliographical references. Title from cover. [3], ill. (some col.); 30 cm; spiral
; Available from British Library Document Supply Centre- DSC:6029. 28071(56); Country of input: International Atomic Energy Agency (IAEA); Includes bibliographical references. Title from cover. [3], ill. (some col.); 30 cm; spiral
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