Z Elem Known Stable Unstable Pred. Gap Nuclear γ (keV) f(γ) (Hz) Kα₁ (keV) f(Kα₁) (Hz) Context 61 Pm 39 0 39 93 54 — — 38.707 9.36×10^18 No stable isotopes; XRF Kα₁ 62 Sm 41 7 34 97 56 333.0 8.05×10^19 40.093 9.69×10^18 ¹⁵³Sm therapy + XRF 63 Eu 40 2 38 95 55 … Continue reading Master Isotope Table + γ & Kα (Batch 4: Z = 61–80)