| Answer | Crossword Clue |
|---|---|
| MESON | Unstable nuclear particle |
| PION | Unstable nuclear particle |
| KAON | Unstable particle |
| MUON | Unstable particle |
| TAUON | Unstable particle |
| MESON | Unstable particle |
| MUON | Unstable subatomic particle |
| KAON | Unstable subatomic particle |
| PSI | ... particle (unstable meson) |
| MESON | Unstable physics particle |
| MUON | Type of unstable particle |
| TENDOWN | Its clue reads "Unstable subatomic particle" |
| metastable | (of a substance or particle) Theoretically unstable but so long-lived as to be stable for practical purposes |
| lambda | uncharged unstable elementary particle that has a mass 2183 times that of an electron and that decays typically into a nucleon and a pion |
