Curium-243
Cm-243 · Curium, Z = 96, A = 243
Curium-243 decays by alpha decay, half-life 29.1 years. Specific activity is 1.87e+12 Bq/g (50.5 Ci/g), so a gigabecquerel comes to 535 µg — weighable, but on an analytical balance. Over a year the activity falls to 97.65%, and over forty years to 38.57%.
Alpha emission is led by 5.785 MeV at 72.9877%, one of 12 recorded lines. None of it reaches through skin, so the limit here is intake, not external dose.
Decay is the only handle: a year leaves 97.65% of today's activity and forty years leaves 38.57%, with ten half-lives at 291 years and a mean life of 42.0 years per atom.
Half-life 29.1 years, 1.87e+12 Bq/g, and no line recorded
| Half-life | 29.1 years (9.183e+8 s) |
| Decay mode | alpha decay |
| Specific activity | 1.87e+12 Bq/g (50.5 Ci/g) |
12 alpha lines, strongest 5.785 MeV
12 recorded lines from 5.622 to 6.066 MeV, the strongest 5.785 MeV at 72.9877% of 100.2% total alpha emission.
| Energy (MeV) | Emission probability (%) |
|---|---|
| 5.7852 | 72.9877 |
| 5.7421 | 11.4666 |
| 5.9918 | 5.6835 |
| 6.0580 | 4.6864 |
| 5.6860 | 1.5954 |
| 6.0662 | 1.4956 |
| 6.0100 | 1.0968 |
| 5.8760 | 0.698 |
| 5.6820 | 0.1994 |
| 5.6390 | 0.1396 |
Activity over decades and centuries
Ten half-lives is 291 years, which puts decay storage out of reach: 38.57% survives forty years. The mean life 1/λ, the quantity that enters an integrated dose, is 42.0 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 | 96.7 years |
| Time to fall to 1 % | 193 years |
| Time to fall to 0.1 % | 290 years |
Limits — intake, not external dose
- Alpha reaches nothing through skin — Cm-243 is an intake problem, not an external one.
- What every sheet leaves out, internal dose included.
Decay and mass calculators for Cm-243
Other Curium nuclides: Cm-242, Cm-244, Cm-245, Cm-246
Computed from the IAEA Nuclear Data Section — Livechart API (ENSDF) and the NIST X-Ray Mass Attenuation Coefficients. Derivations and citations.