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| PDF : |  12010001.pdf |
| title(En) : | Determination of Wood Moisture Content by Neutron Scattering |
| author(En) : | Shigeo Onodera, Saburo Sakamoto, Sadao Sawada |
| information : | Mokuzai Gakkaishi 12(1), 1-5 (1966) |
| assort : | Original Article |
| summary(En) : | The possibility of a neutron scattering method for measuring wood moisture can better be understood by brief consideration of patient point in the principle. Using this method, wood moisture can be measured more directly and non-destructively compared with a number of other methods. Once the fast neutrons reach thermal energies they come to a thermal equilibrium with the surrounding atoms and no longer lose energy. They now scatter in accordance with the theories of gaseous diffusion until they are captured. From a consideration of the σs and ξ in Table 1 it becomes clear why hydrogen should be more effective than other elements in slowing neutrons. If a counter to detect slow neutrons is placed near a source of fast neutrons in wood, the percentage of counts registered will be a function largely of the amount of hydrogen. But this method has been used unsuccessfully for measuring the quantity of water stored in small amount of materials. We found several new approaches in this test. It is described in this paper that moisture determination of wood chip, veneer, and plywood can be measured with considerably high precision by using fast neutron source (Ra 1 mg + Be), a BF3 counter and moderator (water and a block of paraffin). As the paraffin block used as slowing-down material is presumed to be the effective source of slow neutrons, its arrangement and quantity will have a remarkable influence on the counting rate of neutrons. The present experiments, therefore, are performed with a geometrical arrangement in which the paraffin block is kept as close as possible to the detector and the test sample, because this arrangement is found to be the most excellent. The detectable moisture content in the wood of 4 mm in thick and wood chip is 7 per cent, which is obtained from the experimental results with regard to the standard deviation of the counting rate. |