# Lineal energy

The quotient of [math]ε_i[/math] by [math]\bar{l}[/math], where [math]ε_i[/math] is the energy imparted to the matter in a given volume by a single energy-deposition event [math]i[/math], and [math]\bar{l}[/math] is the mean chord length of that volume, thus:

[math] y=\frac{ε_i}{\bar{l}} [/math]

The SI unit of lineal energy is joule per metre (J m^{-1}), often given in KeV μm,^{-1} (ICRP Publication 123, 2013)

*ICRP Glossary entry - May 2019*

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