|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
A barn (symbol: b) is a unit of area equal to 10−28 m2 (100 fm2). Originally used in nuclear physics for expressing the cross sectional area of nuclei and nuclear reactions, today it is also used in all fields of high-energy physics to express the cross sections of any scattering process, and is best understood as a measure of the probability of interaction between small particles.
Survey township, sometimes called Congressional township, as used by the United States Public Land Survey System, refers to a square unit of land, that is nominally six (U.S. Survey) miles (~9.7 km) on a side. Each 36-square-mile (~93 km2) township is divided into 36 one-square-mile (~2.6 km2) sections, that can be further subdivided for sale, and each section covers a nominal 640 acres (2.6 km2).