Search results
Results From The WOW.Com Content Network
The barn is also the unit of area used in nuclear quadrupole resonance and nuclear magnetic resonance to quantify the interaction of a nucleus with an electric field gradient. While the barn never was an SI unit, the SI standards body acknowledged it in the 8th SI Brochure (superseded in 2019) due to its use in particle physics. [1]
[1] [2] The concept of a nuclear cross section can be quantified physically in terms of "characteristic area" where a larger area means a larger probability of interaction. The standard unit for measuring a nuclear cross section (denoted as σ) is the barn, which is equal to 10 −28 m 2, 10 −24 cm 2 or 100 fm 2.
[1] [page needed] 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 m 2 or 10 −24 cm 2. The larger the neutron cross section, the more likely a neutron ...
Although the SI unit of total cross sections is m 2, a smaller unit is usually used in practice. In nuclear and particle physics, the conventional unit is the barn b, where 1 b = 10 −28 m 2 = 100 fm 2. [1] Smaller prefixed units such as mb and μb are also widely used. Correspondingly, the differential cross section can be measured in units ...
A barn is a serious metric unit of area used by nuclear physicists to quantify the scattering or absorption cross-section of very small particles, such as atomic nuclei. [24] One barn is equal to 1.0 × 10 −28 m 2.
The shed is a unit of area used in nuclear physics equal to 10 −24 barns (100 rm 2 = 10 −52 m 2). The outhouse is a unit of area used in nuclear physics equal to 10 −6 barns (100 am 2 = 10 −34 m 2). The barn (b) is a unit of area used in nuclear physics equal to one hundred femtometres squared (100 fm 2 = 10 −28 m 2).
The name probably derives from early neutron-deflection experiments, when the uranium nucleus was described, and the phrases "big as a barn" and "hit a barn door" were used. Barn are typically used for cross sections in nuclear and particle physics. Additional units include the microbarn (or "outhouse") [16] and the yoctobarn (or "shed"). [17] [18]
The physics term "barn", which is a subatomic unit of area, 10 −28 m 2, came from experiments with uranium nuclei during World War II, wherein they were described colloquially as "big as a barn", with the measurement officially adopted to maintain security around nuclear weapons research.