Convert Section (section) to Electron Cross Section (σₑ) instantly.
About these units
Section (section)
A section is a unit of area equal to one square mile, or 640 acres, derived from the PLSS township system. Each township contains 36 sections arranged in a 6-by-6 grid. Sections were historically granted to settlers, railroads, and states for development, education funding, and agricultural expansion. Because a section is large but manageable, it provided a logical unit for dividing land among homesteaders. Even today, the section persists as a foundation of rural property boundaries. Many farms, ranches, and municipal boundaries reference section lines, reflecting how 19th-century surveying still shapes 21st-century land use.
Electron Cross Section (σₑ)
The electron cross section, often denoted σₑ, is not a fixed unit but rather a physical area representing the effective interaction size of an electron in scattering experiments. It is typically expressed in barns or submultiples such as square femtometers (fm²). Electron cross sections are vital in quantum electrodynamics (QED), X-ray scattering, atomic physics, and materials science. These values describe how electrons interact with photons, atoms, or other electrons, determining phenomena such as absorption, conductivity, and radiation shielding. Because electron interactions are probabilistic, σₑ provides a statistical measure of likelihood rather than a physical surface, illustrating how area units are used conceptually at quantum scales.