If you have ever tried to simulate a particle passing through matter, you have almost certainly heard of (GEometry ANd Tracking). Developed by CERN, it is the gold standard for high-energy physics, medical physics, and space radiation studies.

Use it to look up specific classes ( G4RunManager ) or specific physics models. For tutorials, use the examples. For answers, use the mailing list.

April 17, 2026 Category: Tutorials & Tools Reading Time: 5 minutes

But let’s be honest:

It is over 1,000 pages of dense, technical, physics-heavy documentation. Newcomers often open it, search for "Hello World," find nothing, and close the tab in despair.