Chemical properties
Barium ions are usually in divalent state and can serve as surrogate for the lighter homologue calcium.
Nuclear properties
Ba-128 decays by electron capture with a half-life of 2.43(5) days to Cs-128. Cs-128 decays by β+ emission (68.8(13)%) and electron capture (31.2(13)%) with a half-life of 3.640(14) min to stable Xe-128.
Cs-128 emits a high energy positron spectrum with 1260(30) keV average energy and 2907 keV maximum energy (similar to e.g. Cu-62 or Br-76).
Ba-128 emits γ-rays mainly at 273 keV (14.5(7)%) and Cs-128 emits γ-rays mainly at 443 keV (26.8(13)%) and 527 keV (2.41(12)%).
The mean electron energy emitted per Ba-128 decay is 7 keV, the mean photon energy per decay is 66 keV. The mean electron energy emitted per Cs-128 decay is 869 keV, the mean photon energy per decay is 884 keV .
Production
Ba-128 is produced by high energy proton induced spallation of lanthanum carbide or tantalum foil targets at CERN. An off-line mass separation is performed at the CERN MEDICIS facility (Switzerland). The mass-separated ions are implanted into a solid matrix, e.g. a NaCl layer on a noble metal backing. The implanted layer can be dissolved and used directly or can undergo a radiochemical purification step.
Distribution
Activity will be shipped in form of ion-implanted solid samples or liquid solutions of BaCl2. Experiments with Ba-128/Cs-128 are best performed at the WP3 lab AGORA in Lausanne, Switzerland that has already experience with this radionuclide.
Examples of use
| Parameter | Specifications |
|---|---|
| Production route | LaCx(p,spallation) or Ta(p, spallation) |
| Daughter | Decays to Cs-128 (T1/2=3.6 min) that decays to stable Xe-128 |
| Half-life | 2.43 d |
| Processing | Off-line mass separation (solid) or with an additional 1-step column separation (liquid) |
| Primary Container | |
| Product Grade | n.c.a. |
| Physical Form | Solid or liquid |
| Chemical Form | Implanted in solid layer or liquid |
| Radioactive Concentration (gamma spectrometry) | For liquid solution > 50MBq/ml |
| Appearance | mplanted metalic foil with backing or clear colourless solution |
| Radionuclide identification (gamma spectrometry) | 273 keV and 443 keV gamma lines present |
| Radionuclidic Purity (gamma spectrometry) | >99.99% |
| Chemical purity (ICP-OES) | n.a. |
| Molar activity (ICP-OES) | n.a. |
| Apparent Molar Activity | >99% theoretical activity |
| Microbiological quality | n.a. |
| Bacterial endotoxin | n.a. |
| pH (pH strips) | n.a. |
| Additional information | |
| Activity available | 25MBq, few times per year (planning in advance) |
| Activity limit for UN2910 (excepted package) shipment | 20 MBq in dry state or 2 MBq in liquid form |
| Other information | Implanted in Al, Zn or NaCl layer on Au or other metal foils. |