keVc2

KeVc2 is not a distinct physical concept on its own; rather, it is commonly a typographical shorthand for keV/c^2, the unit of mass used in particle physics. The quotient expresses rest mass or mass‑equivalent energy when energies are measured in kilo‑electronvolts.

Etymology and notation: The standard symbol is keV/c^2. In cases with limited formatting, keVc2 may be written without the slash. In natural units (c=1), mass and energy share the same units, blurring the distinction.

Examples: The electron rest mass is about 0.511 MeV/c^2, equivalent to 511 keV/c^2. The muon is about 105.7 MeV/c^2 (approximately 105,700 keV/c^2). The neutron mass is about 939.6 MeV/c^2 (about 939,600 keV/c^2).

Applications and context: keV/c^2 is a common unit when discussing low‑mass particles or low‑energy nuclear transitions, such as X‑ray spectroscopy, beta‑decay endpoints, or certain dark‑matter scenarios. It is less convenient for composite systems with masses in the MeV–GeV ranges, where higher energy units are typically used.

See also: keV, c, E=mc^2.