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Deuterium, 2 H (atomic mass 2.014 101 777 844 (15) Da), the other stable hydrogen isotope, has one proton and one neutron in its nucleus, called a deuteron. 2 H comprises 26–184 ppm (by population, not mass) of hydrogen on Earth; the lower number tends to be found in hydrogen gas and higher enrichment (150 ppm) is typical of seawater.
Neutron porosity measurement employs a neutron source to measure the hydrogen index in a reservoir, which is directly related to porosity. The Hydrogen Index (HI) of a material is defined as the ratio of the concentration of hydrogen atoms per cm 3 in the material, to that of pure water at 75 °F.
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.
Another use of neutron emitters is the detection of light nuclei, in particular the hydrogen found in water molecules. When a fast neutron collides with a light nucleus, it loses a large fraction of its energy. By measuring the rate at which slow neutrons return to the probe after reflecting off of hydrogen nuclei, a neutron probe may determine ...
Further, a nuisance problem of normal hydrogen is its large incoherent neutron cross section, which is nil for 2 H. The substitution of deuterium for normal hydrogen thus reduces scattering noise. Hydrogen is an important and major component in all materials of organic chemistry and life science, but it barely interacts with X-rays.
The high-energy neutrons are slowed when they collide with hydrogen atoms, and the detector then counts the "slowed" neutrons. This count is proportional to the soil's water content, since the hydrogen in this water (H 2 O) is responsible for almost all the hydrogen found in most soils. The gauge calculates the moisture content, subtracts it ...
Neutron probe (e=neutron emitter -- d=detector -- b=shielding -- c=counter). A neutron probe is a device used to measure the quantity of water present in soil. A typical neutron probe contains a pellet of americium-241 and beryllium. The alpha particles emitted by the decay of the americium collide with the light beryllium nuclei, producing ...
Water enriched in molecules that include deuterium instead of normal hydrogen is called heavy water. Deuterium and its compounds are used as a non-radioactive label in chemical experiments and in solvents for 1 H-NMR spectroscopy. [43] Heavy water is used as a neutron moderator and coolant for nuclear reactors.