Nickel-63
Ni-63 · Nickel, Z = 28, A = 63
Nickel-63 decays by beta-minus decay, half-life 100.8 years. Specific activity is 2.09e+12 Bq/g (56.4 Ci/g), so a gigabecquerel comes to 480 µg — weighable, but on an analytical balance. Over forty years the activity falls to 75.95%, and over ten thousand years to 1.4e-28%.
The beta endpoint is 0.0669 MeV, mean 0.0174 MeV over 1 branch. That endpoint stops in 0.0568 mm of acrylic or 0.0268 mm of glass. Of the beta energy, 0.01% turns into X-rays in acrylic and 0.19% in lead.
Decay is the only handle: forty years leaves 75.95% of today's activity and ten thousand years leaves 1.4e-28%, with ten half-lives at 1,008 years and a mean life of 145 years per atom.
Half-life, specific activity and beta endpoint
| Half-life | 100.8 years (3.181e+9 s) |
| Decay mode | beta-minus decay |
| Specific activity | 2.09e+12 Bq/g (56.4 Ci/g) |
| Beta endpoint / mean | 0.0669 MeV / 0.0174 MeV |
0.0568 mm of acrylic stops the 0.0669 MeV endpoint
Katz–Penfold fit to the 0.0669 MeV endpoint — ±10%, and a stopping thickness rather than an attenuation length. Why the material matters more than the thickness.
| Absorber | Range for the endpoint (mm) |
|---|---|
| acrylic | 0.0568 |
| aluminum | 0.0248 |
| water | 0.0671 |
| glass | 0.0268 |
| Shield material | Fraction of beta energy converted to X-rays |
|---|---|
| acrylic (Z ≈ 6) | 0.01% |
| lead (Z = 82) | 0.19% |
Activity over millennia
Ten half-lives is 1,008 years, which puts decay storage out of reach: 75.95% survives forty years. The mean life 1/λ, the quantity that enters an integrated dose, is 145 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 | 335 years |
| Time to fall to 1 % | 670 years |
| Time to fall to 0.1 % | 1,005 years |
Limits of these range figures
- 0.0568 mm of acrylic for the 0.0669 MeV endpoint: a ±10% fit, and not a skin dose.
- What every sheet leaves out, internal dose included.
Beta and decay calculators for Ni-63
Other Nickel nuclides: Ni-59
Computed from the IAEA Nuclear Data Section — Livechart API (ENSDF) and the NIST X-Ray Mass Attenuation Coefficients. Derivations and citations.