[en] ³⁶Cl has become a popular tool for hydrogeologists to use when evaluating flow rates, ages and origins of groundwaters, in particular in systems where flow paths are long and/or flow rates are slow. The ratio ³⁶Cl/Cl and total chloride are measured in water samples, and the different processes acting upon the stable and radioactive isotopes were assessed. By comparing the theoretical fallout of ³⁶Cl to that observed in rainfall, and that seen in shallow, recharge groundwaters, it was possible to evaluate the processes involved in the incorporation of chloride to groundwater systems. It was found that ³⁶ Cl concentration in shallow groundwater aquifers reflects quite well theoretical and rainfall values, though local climatic effects are important

[en] Full text: The Radiation Monitoring System that we present in this paper (RMS for the OPAL reactor, Sydney, Australia) encompasses all radiation monitoring tasks, being performed in a continuous mode, on processes involving liquid and gases, as well as area supervision inside the reactor. Information brought by the RMS is reported to the Reactor Control Monitoring System as well as the reactor protection systems. The monitoring of liquids inside the facility is served by the following subsystems integrating the RMS: Liquid Effluent Monitor (LEM), Failed Fuel Elements Monitor (FFEM), Secondary Water Activity Monitor (SAMO), Active Liquids Monitor (ALMO) and Waste Streams Monitor (WASMO). The monitoring of gases is achieved by the Air Effluent Monitor subsystem (AEM) and the Intelligent Air Effluent Monitor subsystem (AEMI). The area radiation monitoring function is covered by the ARM network sub-system and dedicated process monitoring (hot cells, transfer systems, etc). Today the whole system is fully operational at Opal reactor

[en] Several aspects of the AMS program at the TANDAR laboratory are discussed. The current activities are focused on environmental and cosmological applications. One of the projects has been the study of the global fallout of the radioisotope ³⁶Cl and its latitudinal distribution in the southern hemisphere. We have also undertaken some of the preparatory work to measure the concentration of several radioisotopes in extraterrestrial samples obtained from a meteorite fall in northern Argentina. An important fraction of our effort in pursuing these studies has been the optimization of the technique in our 20 UD tandem. We discuss the results of recent tests carried out to evaluate the current capabilities of the accelerator regarding general stability, predictability and transmission efficiency, following the upgrading and adaptation activities

[en] Fusion cross sections have been measured for ¹²C+¹⁴⁴Sm at bombarding energies in the range 46.5≤E_lab≤75 MeV by off-line observations of x rays and gamma rays emitted in the decay of the evaporation residues and their daughters. Elastic scattering angular distributions for the same system have also been measured in the range 49≤E_lab≤63 MeV. These data were used to obtain the parameters of an optical-model potential. It was found that a simultaneous description of both elastic scattering and fusion leads to an energy-dependent potential, with its real and imaginary parts connected by a dispersion relation

[en] Possible effects of hexadecapole nuclear deformations on subbarrier fusion cross sections are investigated. The ¹⁶O on ¹⁶⁶Er and ¹⁷⁶Yb reactions have been measured at beam energies ranging from 64 to 100 MeV. The ¹⁶⁶Er and ¹⁷⁶Yb data and already existing ¹⁵⁴Sm data were analyzed in terms of a model including both quadrupole and hexadecapole deformations. Theoretical predictions follow qualitatively the trend of the experimental data

[en] One- and two-charge-transfer reactions were studied in the ¹²C+¹⁹⁷Au and ¹⁶O+¹⁹⁷Au systems at bombarding energies around the Coulomb barrier. Transfer probabilities for the same Coulomb reduced radius, extracted from angular distribution measurements, show a strong dependence on the bombarding energy and are interpreted within a semiclassical model. Quasielastic scattering data are analyzed in terms of an energy-dependent optical model. copyright 1996 The American Physical Society

[en] Evaporation-residue and transfer reaction cross sections have been measured for ¹²C+^108,110Pd and ⁷Li+^113,115In. The residual nuclei were detected and identified by off-line observation of the γ rays emitted in their radioactive decays. The 3n evaporation channel is the dominant decay mode following the fusion of ¹²C+¹¹⁰Pd and ⁷Li+¹¹⁵In at sub- and near-barrier energies, and ¹²C+¹⁰⁸Pd and ⁷Li+¹¹³In at bombarding energies just above the Coulomb barrier. The experimental evaporation-residue excitation functions are compared with calculations obtained using simplified coupled-channel and statistical models. In these calculations it is not necessary to include transfer channels to explain the data in the case of ¹²C+¹¹⁰Pd and ¹²C+¹⁰⁸Pd but they must be taken into account for ⁷Li+¹¹⁵In and ⁷Li+¹¹³In. copyright 1996 The American Physical Society

[en] One neutron transfer cross sections in the systems ³²S+¹⁴⁴Sm and ³²S+ ¹⁶⁶Er have been measured at energies close to the Coulomb barrier. Mass and charge identification was achieved using characteristic x rays. Transfer probabilities were analyzed by considering barrier penetration mechanisms. Possible enhancement effects due to permanent quadrupole deformations are investigated and compared with the experimental results

[en] Fusion cross sections for ¹⁶O+¹⁴⁴Nd at bombarding energies ranging from E_c.m.=54.0 to 67.5 MeV were measured by observation of the delayed x rays emitted in the radioactive decay of the evaporation residues and their daughters. The experimental fusion excitation function was analyzed with a barrier penetration model which includes coupling to inelastic channels. The theoretical average angular momenta were calculated and compared with already existing data deduced from γ-multiplicity measurements

[en] The accelerator-mass-spectrometry (AMS) technique developed at the TANDAR Laboratory in Buenos Aires is being mainly dedicated to environmental and astrophysical problems. For this purpose, from the earliest stages the activities have been aimed to address the upgrading and optimization of different components of the accelerator. Taking into account that only an excellent performance of the ion source and of the accelerator itself will provide reliable conditions to apply this technique, the work focused on the following areas: a) ion source and sample preparations, b) general stability and beam transmission through the accelerator, and c) detection systems. In this work a summary of these activities is given and the progress achieved along all these lines is described. Finally the initial results of the application of AMS to the measurement of the latitudinal distribution of the long-lived radioisotope ³⁶Cl in rainwater samples, and to the study of ⁵⁹Ni in meteorite material are presented. (author)