[en] The development of an intense and pure post-accelerated ⁷Be beam at Louvain-la-Neuve will be discussed. Given its properties (metallic nature, long half-life (53 days)) and the special beam parameters required (multi-charge ions, high purity), a range of special techniques had to be investigated. At Louvain-la-Neuve, ⁷Be is produced by irradiating a lithium target with 30 μA of 27 MeV protons and is extracted using offline chemical separation techniques. Because of the large amounts of activity required, the chemistry has to be adapted for use in hotcells. The ionization is performed with an Electron Cyclotron Resonance ion source with the ⁷Be injected in the source by means of sputtering. Special techniques have to be used to prevent the beryllium atoms from being lost on the plasma chamber walls. A dedicated heated plasma chamber for the ion source was developed. The ionization efficiency was increased by studying the chemistry involved in the ion source. The atoms are ionized to the 1+ or 2+ charge state and injected in the CYCLONE cyclotron for acceleration. To further reduce the ⁷Li contamination, the cyclotron is tuned as a mass separator, suppressing the Li intensity by about 10⁵. The accelerated beam is then stripped to the 4+ state to eliminate the remaining ⁷Li. This method allowed us to produce a ⁷Be beam with intensities up to a few 10⁷ pps and with a very high degree of purity. Experiments with energies ranging from 4.4 MeV (1+) to 56 MeV (2+) have been performed

[en] Suitable ¹⁷O samples are required for the study of the ¹⁷O(n,α)¹⁴C reaction with various detectors. The electrospraying of metal oxides enriched in ¹⁷O onto an Al substrate yielded negative results: no ¹⁷O(n_th,α) reactions were observed when irradiating these samples with thermal neutrons. These tests demonstrated the need to minimize the ¹⁰B content in sample and backing, since the ¹⁰B(n_th,α₁) reaction causes a strongly disturbing background. Good results were obtained in the reactor experiments using gaseous samples (¹⁷O enrichments of 58.2%, 72.1% and 85.5%) with a dedicated experimental setup. The experimental conditions being quite different at accelerators, an alternative method was developed to prepare samples suited for use in ionization chambers. For this purpose, ¹⁷O ions were implanted in ultra-pure Al foils. The thickest sample prepared in this way contains 8x10¹⁸ atoms of ¹⁷O, with a ¹⁰B/¹⁷O ratio of 10^-4

[en] At the end of 1999, a first on-line RIB was accelerated, extracted and separated with the new cyclotron, CYCLONE44. An efficiency of 7% (from ion source exit to experiment target), resulting in 6x10⁸ pps of ¹⁹Ne³⁺, was obtained. Up to 9 kW of beam power has been put on the LiF target giving increased intensities for ⁶He, ¹⁸Ne and ¹⁵O. A new accelerated and pure ⁷Be-beam of 2x10⁷ pps has been produced, using the sputtering electrode in the ECR-source. Production tests of ¹⁴O using CYCLONE110 have started in view of their acceleration with CYCLONE44

[en] The Louvain-la-Neuve ECR ion source is used to ionize metallic radioactive elements like Be-7 (T_1/2=53d) for postacceleration in its radioactive beam facility. Because of the minute quantities of primary material available, dedicated techniques had to be developed to inject the radioactive atoms in a controlled manner and to recycle the atoms lost on the plasma chamber walls. For this purpose, a heated plasma chamber has been constructed which allows the use of ''on-line chemistry in the source'' to effectively recycle the deposited material. The presence of a radioactive tracer proved to be a strong diagnostic tool to locate the material loss in the different parts of the source. This development resulted in the production of a postaccelerated beam of Be-7 in 1⁺ and 2⁺ charge states. Up to 110 h of continuous beam have been provided with primary material quantities of a few ng. The total efficiency of the source reached a few percent. These beams were initially developed for experiments in nuclear physics. The implantation of Be-7 is now also used as a powerful tool to measure the wear properties of various materials like ceramics and amorphous carbon layers. This will be illustrated with a few examples

[en] The ³⁷Ar(n, p)³⁷Cl and ³⁷Ar(n, α )³⁴S reactions were studied for the first time as a function of the neutron energy at the neutron spectrometer GELINA at the IRMM in Geel (Belgium). For the ³⁷Ar(n, α )³⁴S reaction, cross section data were obtained covering the neutron energy region from 10 meV up to 100 keV, but the sensitivity was too low to observe the ³⁷Ar(n, p)³⁷Cl reaction. In the low energy region, the (n, α ) cross-section was shown to have a 1 / v shape, while in the keV region several resonances were determined and subsequently analysed. Finally, the Maxwellian averaged cross section value was calculated at astrophysically relevant temperatures

[en] At the Centre de Recherches du Cyclotron at Louvain-la-Neuve, we have used the ion implantation technique to provide both radioactive and stable nuclear targets using an ECR ion source. This paper will describe the realization of ¹⁷O samples produced for the measurement of the ¹⁷O(n,α)¹⁴C reaction. The motivation for investigating this reaction and the specific needs for the target are given in another article of this conference (Nikos Prantzos, Sotiris Harinopulos (Eds.), Proceedings of the International Symposium on Nuclear Astrophysics 'Nuclei in the Cosmos', Volos, Greece, 6-11 July, 1998, Editions Frontiere, Dreux, p. 33). Here, we will limit ourselves to the technical aspects of the sample production

[en] An intense beam of Be-7 (T1/2=53 days) has been developed at the CYCLONE radioactive beam facility in Louvain-la-Neuve. Because of the Be-7 properties (long half-life, metallic nature) novel methods have been used for the production, ionisation and post-acceleration of this element. A dedicated ECR source has been developed to inject the minute quantities of radioactive atoms in a controlled manner and to recycle the Be-7 atoms lost on the plasma chamber walls. This Be-7 beam was initially requested for nuclear astrophysics experiments but is now also used for industry. The implantation of Be-7 is indeed a powerful tool to measure the wear properties of materials like ceramics or amorphous carbon layers which are difficult to activate with protons. This application will be illustrated with a few examples. (author)

[en] The radioactive isotope ¹⁴C is formed in nuclear reactors through five different neutron absorption reactions by isotopes of carbon, nitrogen and oxygen: ¹³C(n, γ), ¹⁴N (n, p),¹⁵N(n, d), ¹⁶O(n, ³He) and ¹⁷O(n, α). These materials are present as normal or impurity components of the fuel elements, the cooling water or structural material, depending on the type of reactor. In most cases, however, neutron reactions with ¹⁴N and ¹⁷O are the dominant production sources of ¹⁴C. Most of the ¹⁴C formed in the fuel for example will be converted to a gaseous form at the fuel reprocessing plant unless specific steps to remove it are undertaken.

[en] The ³⁷Ar(n_th,α)³⁴S and ³⁷Ar(n_th,p)³⁷Cl reactions were studied at the high flux reactor of the ILL in Grenoble. For the ³⁷Ar(n_th,α₀)³⁴S and ³⁷Ar(n_th,p)³⁷Cl reaction cross sections, values of (1070 ± 80) b and (37 ± 4) b, respectively, were obtained. Both values are about a factor 2 smaller than the results of older measurements. The observed suppression of the ³⁷Ar(n_th,α₁)³⁴S transition could be verified from theoretical considerations. Finally, evidence was found for the two-step ³⁷Ar(n_th,γα)³⁴S process

[en] Due to the bankruptcy in 2012 of a radiopharmaceutical production plant, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials (ONDRAF-NIRAS), according to its legal mission, had to take on the remediation and dismantling of all its installations. These include two cyclotrons and various hot cells and laboratories. A specific concern with the site was the presence of numerous isotopes in very different proportions depending on the equipment or installation. The preparation of the dismantling included a large effort to define and implement a robust waste management strategy. This strategy was based on minimizing radioactive waste for final disposal by decontamination, metal melting with unconditional release and maximizing conditional and unconditional release for other materials including lightly activated concrete from the cyclotron bunkers. It has been implemented in four important steps: acquiring a good knowledge of the history of the installation, establishing complete isotope vectors for all areas, developing a comprehensive general methodology for characterizing the materials and the implementation of a high degree of material sorting. Nine years into the dismantling, this strategy has proven to be very successful. More than 50% of all materials have been unconditionally released or recycled. With thousands of characterisations performed during the project, no significant changes to the initial isotope vectors have been necessary. The general methodology has been successfully applied on the most basic items up to, and including, complete buildings. For the remaining radioactive waste, the physical-chemical and radiological characterisation satisfied or exceeded the proposed stringent requirements set by ONDRAF/NIRAS for the surface disposal facility for low-level radioactive waste currently in development. This shows that successful waste management can be realized in the reality of day-to-day operations in dismantling. (author)