Target Techniques for the isolde on-line isotope separator

Investigations on the thermal release of iodine from liquid eutectic lead-bismuth alloy

The release of iodine from liquid eutectic lead-bismuth alloy (LBE) under a flowing Ar/7%H2 atmosphere has been studied in a temperature range from 428 to 1223 K using γ-ray spectroscopy. During short-term experiments, significant amounts of iodine evaporate from liquid LBE at temperatures higher than 800 K. Long-term experiments reveal that the release of iodine at temperatures of relevance to technical applications, such as liquid metal spallation targets or Accelerator Driven Systems (ADS), is below our detection limits for periods up to 7 days. The release rate is determined by the desorption/evaporation process rather than by diffusion within the liquid alloy.

Study of the thermal release behaviour of mercury and thallium from liquid eutectic lead-bismuth alloy

The release of mercury and thallium from liquid eutectic lead-bismuth alloy (LBE) under a flowing Ar/7%-H2 atmosphere has been studied in the temperature range from 408 to 1292 K using γ-ray spectroscopy. For technical applications such as liquid metal spallation targets or accelerator driven systems, where liquid LBE is planned to be used as target material, the release of radioactive mercury isotopes produced by spallation is expected to be one of the major safety issues.

During short-term experiments significant amounts of mercury begin to evaporate from liquid LBE at temperatures starting from about 475 K. 80% of the mercury present in the sample is released from samples of approximately 1.5–3 g within one hour at temperatures higher than 625 K. Thallium release in the temperature range investigated is below experimental error. Long-term experiments reveal that even at temperatures as low as 476 K about 25% of the mercury present in the samples is released per day under a flowing Ar/7%-H2 atmosphere.

Deformation of the N=Z nucleus 76Sr using beta-decay studies

A novel method of deducing the deformation of the N=Z nucleus 76Sr is presented. It is based on the comparison of the experimental Gamow-Teller strength distribution B(GT) from its beta decay with the results of quasi-random-phase approximation calculations. This method confirms previous indications of the strong prolate deformation of this nucleus in a totally independent way. The measurement has been carried out with a large total absorption gamma spectrometer, "Lucrecia," newly installed at CERN-ISOLDE.

A practical target system for accelerator-based BNCT which may effectively double the dose rate

A dose-limiting component of a proton accelerator-based source of epithermal neutrons is the neutron production target. Possible targets are lithium, producing high yield but having low melting point and thermal conductivity, and beryllium, presenting less engineering problems but a much smaller neutron yield. We propose that a hybrid Be-Li target would provide the best of both worlds, with the upstream beryllium component producing neutrons and providing containment to the lithium, and the downstream liquid lithium in turn producing further neutrons as well as cooling the beryllium. The engineering considerations associated with such a target system are within the range of current technology. Calculations suggest a yield of such a practical target that is at least double that from pure beryllium.

A new type of 81Rb-81mKr generator for medical use

A new 81Rb-81mKr generator is described. The new generator-type is suitable for ventilation and perfusion studies. By implantation of 60 keV 81Rb+-ions into Mylar or polyethylene foils, the pure 81mKr daughter can be eluted by an air-flow or by an isotonic NaCl solution.