Barium ions are usually in divalent state and can serve as surrogate for the lighter homologue calcium.
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 .
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.
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
|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|
|Processing||Off-line mass separation (solid) or with an additional 1-step column separation (liquid)|
|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|
|pH (pH strips)||n.a.|
|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.|