A Gamma-spectrometer for determination of density distribution and moisture distribution in building materials

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ConferenceMoisture and Humidity: Measurement and Control in Science and Industry : Proc. Int. Symp.: 15 April 1985, Washington, D.C., USA
Pages48590; # of pages: 396
Subjectspectrometers; building materials; density (physics); moisture content; dual beam gamma spectrometer; instrumentation; 55cs137 and 95am241 source; sodium iodide (thallium) crystal and multichannel analyzer detector; computer control; mass attenuation coefficients of water; moisture distribution profile; Hygrothermal properties
AbstractA dual-beam gamma-spectrometer has been designed and installed, its source an assembly of [55]Cs[137] and [95]Am[ 241]. The detector consists of a sodium iodide (thallium) crystal and a multichannel analyser, each channel screening a specified region approximately equal to 48 kJ mol[-1] in the combined spectra. The source and the detector are mounted on separate towers that can be moved along a space matrix defined by vertical and horizontal coordinates with a precision better than 0.02 mm; movement of the towers is controlled and synchronized by computer. Intensities of the gamma ray in the regions of interest (round the two characteristic peaks of 5.79 and 63.88 GJ mol[-1] in the spectra, as passed through homogeneous media like air, water or aqueous solutions) are recorded, wih a typical standard deviation of 0.2% under the optimized experimental conditions. Computer programs are used to define the parameters of each test, to run the test, and to collect data. The mass attenuation coefficients of water for both energy regions have been determined and agree with accepted literature values within 1%. A profile is presented of moisture distribution in a block of medium-density glass fiber while drying.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number24693
NPARC number20375280
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Record identifierd84e58e5-7446-4b1d-964f-957a9cbb73d0
Record created2012-07-23
Record modified2016-05-09
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