Jt. Karsulovic et al., The use of linear attenuation coefficients of gamma radiation for detecting knots in Pinus radiata, FOREST PROD, 49(2), 1999, pp. 73-76
This paper reports on the preliminary results of a research project designe
d to develop an automated defect-detection and timber-classifying system fo
r Pinus radiata (D. Don), by using a collimated gamma-ray photon beam from
a 59.5 keV (Am241)energy source. The analysis was made by measuring the lin
ear attenuation coefficients resulting from scanning along the radial and t
angential directions of six specimens of Pinus radiata, with densities that
ranged from 430 g/cm(3) to 620 g/cm(3). The samples were 4.2 cm thick by 1
2.5 cm wide by 20 cm in length, and the moisture content of the samples ran
ged from 8 to 12 percent. The samples included sound knots that varied from
2 cm to 5 cm in diameter. It was established that the linear attenuation c
oefficient was a good indicator of the presence of knots in the samples. Th
e results showed a high degree of sensitivity of the attenuation coefficien
t to variations in the density of the material, based on the high degree of
correlation that was obtained (r(2) = 0.95), both in the radial and tangen
tial directions of irradiation.