Muons Scan a Battery
A muon is like an electron, but 207 times heavier. When it slams into matter, it slows down like a bullet in a sandbank, and at every bend in its path it emits X-rays. Those X-rays tell you which atoms the muon encountered: that's the idea behind a technique called MIXE. It lets you peer inside an object without dismantling it, like an X-ray for materials.