Physics:Neutron moisture gauge
A neutron moisture meter is a moisture meter utilizing neutron scattering. The meters are most frequently used to measure the water content in soil or rock. The technique is non-destructive, and is sensitive to moisture in the bulk of the target material, not just at the surface.
Water, due to its hydrogen content, is an effective neutron moderator, slowing high-energy neutrons. With a source of high-energy neutrons and a detector sensitive to low-energy neutrons (thermal neutrons), the detection rate will be governed by the water content of the soil between the source and the detector. The neutron source typically contains a small amount of a radionuclide. Sources may emit neutrons during spontaneous fission, as with californium; alternatively, an alpha emitter may be mixed with a light element for a nuclear reaction yielding excess neutrons, as with americium in a beryllium matrix.
References
- Visvalingam, M.; Tandy, J. D. (1972). "The Neutron Method for Measuring Soil Moisture Content-A Review". Journal of Soil Science 23 (4): 499–511. doi:10.1111/j.1365-2389.1972.tb01680.x. https://hull-repository.worktribe.com/380529/1/VISVALINGAM_et_al-1972-Journal_of_Soil_Science.pdf.
- Pershin, A. A.; Glushkova, L. T. (1980). "Nomenclature and design principles of neutron moisture meters and means of calibrating them". Measurement Techniques 23 (4): 348–351. doi:10.1007/BF00831296.
- Wahid, P. A. (2001). An Introduction to Isotopes and Radiations. ISBN 978-81-7764-060-1. https://books.google.com/books?id=Rak15QqnXqoC&pg=PA131.
- "Neutron moisture meter". http://www.sowacs.com/literature/lit_nmm.html.
- Ltd., Nuclear Enterprises (G.B.) (1958). "Neutron moisture gauge". Journal of Scientific Instruments 35 (12): 476. doi:10.1088/0950-7671/35/12/426. Bibcode: 1958JScI...35..476E.
- Lowenthal, Gerhart C; Airey, P. L (2001-08-27). Practical applications of radioactivity and nuclear radiations: an introductory text for engineers, scientists, teachers and students. p. 217. ISBN 978-0-521-55305-6. https://archive.org/details/practicalapplica0000lowe.
- Kirda, C.; Reichardt, K. (1992). "Comparison of neutron moisture gauges with nonnuclear methods to measure field soil water status". Scientia Agricola 49: 111–121. doi:10.1590/S0103-90161992000400015.
- Nagpal, M K; Mehta, P P; Nagpaul, K K; Rama (1973). "Characteristics of a neutron moisture gauge with a solid state detector". Pramana 1 (2): 112. doi:10.1007/BF02847186. Bibcode: 1973Prama...1..112N.
- "DROUGHT_WEB_NEUTRON_PRB". http://ucmanagedrought.ucdavis.edu/PDF/DROUGHT_WEB_NEUTRON_PRB.pdf.
- "BIBLIOGRAPHY – NEUTRON PROBE". Archived from the original on 2011-06-28. https://web.archive.org/web/20110628234609/http://www.iaea.org/programmes/nafa/d1/public/d1_pbl_2_1.pdf.
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