When a D0-meson decays, it produces daughter particles called pions and kaons.

D0-介子衰变时会产生叫做π介子和K介子的子粒子。

Instead, they collide with air molecules around 25 kilometers above the ground and create new particles like pions.

相反，它们与地面上约 25 公里处的空气分子碰撞， 产生新的粒子， 如介子。