ultratrack

physics

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 14, 2026

Quick Summary

The term "ultra" means going beyond a limit or being extreme. In physics, specifically concerning radiation, the concept of an "ultratrack" refers to the region outside the immediate path of a charged particle where energy deposition occurs. This energy deposition in the ultratrack is mainly due to electronic excitation and ionization caused by secondary electrons that have enough energy to move away from the particle's direct path. Unlike the "infratrack," which is a very narrow region close to the particle's trajectory with a high density of energy deposition, the ultratrack does not have clearly defined physical boundaries. Its extent is generally considered to be the maximum range of these secondary electrons moving sideways from the particle's trajectory.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

radiation
Linear energy transfer and track structure
…this outer region, or “ultratrack,” is due primarily to electronic excitation and ionization by secondary electrons having sufficient energy to escape from the infratrack. In contrast to the infratrack, the ultratrack does not have well-defined physical bounds. Its spatial extent may reasonably be equated with the maximum range of…
Read More
…this outer region, or “ultratrack,” is due primarily to electronic excitation and ionization by secondary electrons having sufficient energy to escape from the infratrack. In contrast to the infratrack, the ultratrack does not have well-defined physical bounds. Its spatial extent may reasonably be equated with the maximum range of…
Read More