Table 2. Decay times to 0.1 nCi radioactivity for different materials, masses and exposure times.
Values are calculated for a reference flux of 108 neutrons cm−2 s−1, employing the NIST neutron activation calculator (NIST, 2017 ▸).
| Mass (g) | ||||||
|---|---|---|---|---|---|---|
| 1 | 10−3 | 5 × 10−5 | ||||
| Exposure time (h) | ||||||
| 1 | 10 | 1 | 10 | 1 | 10 | |
| Material | Decay time | |||||
| Copper | 8 d | 10 d | 3 d | 4 d | 14 h | 2.2 d |
| Nickel | 1 d | 18 y | – | 5 h | – | – |
| Cobalt | 38 y | 56 y | 2 h | 3 y | 2 h | 2 h |
| Titanium | 1 h | 1 h | 10 min | 10 min | – | – |
| Zinc | 2 y | 5 y | 4 h | 9 h | – | 1 h |
| Iron | 1 y | 10 y | – | – | – | – |
| Aluminium | 1 h | 1 h | – | – | – | – |
| Palladium | 2 months | 4 months | 2 d | 4 d | – | 2 d |
| Chromium | 7 months | 1 y | – | 1 month | – | – |
| SiO2 | 20 h | 1 d | – | – | – | – |
| Si | 23 h | 1 d | – | 1 h | – | – |
| Borosilicate | 20 h | 1 d | – | – | – | – |
| h-PMMA/d-PMMA | – | – | – | – | – | – |