| dbo:abstract |
مقطع نيوتروني في فيزياء نووية (بالإنجليزية:neutron cross-section) يعرف المقطع النيوتروني الكلي لعنصر بأنه المساحة الفعالة لذرة من العنصر التي تشترك في . تمثل تلك المساحة بوحدة سنتيمتر مربع، ونظرا لصغرها وصغر الذرة فقد ابتكر الفزيائيون وحدة صغيرة مناسبة هي البارن. (ar) In nuclear physics, the concept of a neutron cross section is used to express the likelihood of interaction between an incident neutron and a target nucleus. The neutron cross section σ can be defined as the area in cm2 for which the number of neutron-nuclei reactions taking place is equal to the product of the number of incident neutrons that would pass through the area and the number of target nuclei. In conjunction with the neutron flux, it enables the calculation of the reaction rate, for example to derive the thermal power of a nuclear power plant. The standard unit for measuring the cross section is the barn, which is equal to 10−28 m2 or 10−24 cm2. The larger the neutron cross section, the more likely a neutron will react with the nucleus. An isotope (or nuclide) can be classified according to its neutron cross section and how it reacts to an incident neutron. Nuclides that tend to absorb a neutron and either decay or keep the neutron in its nucleus are neutron absorbers and will have a capture cross section for that reaction. Isotopes that undergo fission are fissionable fuels and have a corresponding fission cross section. The remaining isotopes will simply scatter the neutron, and have a scatter cross section. Some isotopes, like uranium-238, have nonzero cross sections of all three. Isotopes which have a large scatter cross section and a low mass are good neutron moderators (see chart below). Nuclides which have a large absorption cross section are neutron poisons if they are neither fissile nor undergo decay. A poison that is purposely inserted into a nuclear reactor for controlling its reactivity in the long term and improve its shutdown margin is called a burnable poison. (en) 中子截面（英語：Neutron cross-section）常用於核物理學與粒子物理學中，表示入射中子與靶核交互作用的一種帶有機率意義的常數。單位以barn表示，等於10−24cm2。中子截面與中子通量、核反應速率計算有關，例如：計算一座核電廠的功率。 (zh) |
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https://mragheb.com/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Neutron%20Cross%20Sections.pdf https://www.ncnr.nist.gov/resources/n-lengths/ https://xsplot.com/ https://environmentalchemistry.com/yogi/periodic/crosssection.html |
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مقطع نيوتروني في فيزياء نووية (بالإنجليزية:neutron cross-section) يعرف المقطع النيوتروني الكلي لعنصر بأنه المساحة الفعالة لذرة من العنصر التي تشترك في . تمثل تلك المساحة بوحدة سنتيمتر مربع، ونظرا لصغرها وصغر الذرة فقد ابتكر الفزيائيون وحدة صغيرة مناسبة هي البارن. (ar) 中子截面（英語：Neutron cross-section）常用於核物理學與粒子物理學中，表示入射中子與靶核交互作用的一種帶有機率意義的常數。單位以barn表示，等於10−24cm2。中子截面與中子通量、核反應速率計算有關，例如：計算一座核電廠的功率。 (zh) In nuclear physics, the concept of a neutron cross section is used to express the likelihood of interaction between an incident neutron and a target nucleus. The neutron cross section σ can be defined as the area in cm2 for which the number of neutron-nuclei reactions taking place is equal to the product of the number of incident neutrons that would pass through the area and the number of target nuclei. In conjunction with the neutron flux, it enables the calculation of the reaction rate, for example to derive the thermal power of a nuclear power plant. The standard unit for measuring the cross section is the barn, which is equal to 10−28 m2 or 10−24 cm2. The larger the neutron cross section, the more likely a neutron will react with the nucleus. (en) |
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مقطع نيوتروني (ar) Neutronenquerschnitt (de) Neutron cross section (en) 中子截面 (zh) |
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