In the stream of cosmic rays, particles flying toward us from the depths of the Galaxy, titanium is rare. Its nuclei are almost indistinguishable from iron: both are heavy, and both leave similar tracks in detectors. But in the ATIC experiment, using a silicon matrix, researchers managed to separate titanium from iron and trace how their ratio changes with energy.

In everyday terms, it's like telling apart two similar twins in a crowd by a barely visible birthmark. The silicon matrix acts as a very attentive observer that notices the difference in how particles slow down in matter. Titanium is slightly lighter than iron, and at high energies this difference becomes more pronounced.

The result is a curve of the titanium-to-iron ratio as a function of energy. Such data are needed to test how cosmic rays are accelerated and how much matter they traverse on their way to Earth. Rare nuclei like titanium act as markers that allow us to reconstruct the particle's journey history.