[en] It is discussed why track detectors such as CR-39 and CN-85, which are only composed of light elements, are highly sensitive and efficient compared with detectors such as glass and mica, which are partly or fully composed of heavier elements. Weak scattering of incident particles by light target atoms does not significantly deviate incident particles from their straight trajectories while the target atoms recoil considerably, damaging the detector. Heavier atoms scatter incident particles through wide angles, significantly deviating them from their straight paths while the target atoms recoil weakly, producing less damage. Simulations are presented to demonstrate these concepts about nuclear track formation