Curium-245
Cm-245 · Curium, Z = 96, A = 245
A gigabecquerel of Cm-245 is 156 mg of material, which follows from a specific activity of 6.41e+9 Bq/g (0.173 Ci/g). Curium-245 decays by alpha decay with a half-life of 8423 years; forty years leaves 99.67% of today's activity and ten thousand years leaves 43.91%.
Alpha emission is led by 5.361 MeV at 93.2%, one of 9 recorded lines. None of it reaches through skin, so the limit here is intake, not external dose.
Decay is the only handle: forty years leaves 99.67% of today's activity and ten thousand years leaves 43.91%, with ten half-lives at 84,228 years and a mean life of 12,152 years per atom.
Half-life 8423 years, 6.41e+9 Bq/g, and no line recorded
| Half-life | 8423 years (2.658e+11 s) |
| Decay mode | alpha decay |
| Specific activity | 6.41e+9 Bq/g (0.173 Ci/g) |
9 alpha lines, strongest 5.361 MeV
9 recorded lines from 5.234 to 5.529 MeV, the strongest 5.361 MeV at 93.2% of 100.5% total alpha emission.
| Energy (MeV) | Emission probability (%) |
|---|---|
| 5.3611 | 93.2 |
| 5.3043 | 5 |
| 5.4885 | 0.83 |
| 5.5290 | 0.58 |
| 5.3716 | 0.43 |
| 5.2344 | 0.32 |
| 5.2728 | 0.07 |
| 5.4361 | 0.04 |
| 5.3711 | 0.02 |
Activity over millennia
Ten half-lives is 84,228 years. On any timescale a facility can be planned over the activity is constant — 99.67% is left after forty years — and the mean life 1/λ is 12,152 years.
| Elapsed | Fraction remaining |
|---|---|
| 1 half-life | 50.0 % |
| 2 half-lives | 25.0 % |
| 5 half-lives | 3.13 % |
| 10 half-lives | 0.0977 % |
| Time to fall to 10 % of today's activity | 27,980 years |
| Time to fall to 1 % | 55,960 years |
| Time to fall to 0.1 % | 83,940 years |
Limits — intake, not external dose
- Alpha reaches nothing through skin — Cm-245 is an intake problem, not an external one.
- What every sheet leaves out, internal dose included.
Decay and mass calculators for Cm-245
Other Curium nuclides: Cm-242, Cm-243, Cm-244, Cm-246
Computed from the IAEA Nuclear Data Section — Livechart API (ENSDF) and the NIST X-Ray Mass Attenuation Coefficients. Derivations and citations.