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  • 1 CEN/Saclay Département de Recherche et Analyse-Service d’Analyse et d’Etudes en Chimie Nucléaire et isotopique-Laboratoire d’Analyse par Réactions Nucléaires B. P. No 2 91190 Gif-sur-Yvette France
  • 2 Laboratoire des Isotopes-Médecine I-Hôpital Bichat Groupe de Recherches INSERM U 82 170 boulevard Ney 75 Paris France
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Abstract  

The photonuclear reactions used for this isotopic analysis are as follows:16O(γ, n)15O threshold energy 15.7 MeV;18O(γ, p)17N threshold energy 16.3 MeV.15O is a pure β+ emitter of half-life 2.03 minutes, whereas17N presents a 4.2 second neutron emission. The principle of the method is founded on the simultaneous measurement of the above characteristic radioactivities, the intensities of which are proportional to the respective quantities of16O and18O present in the irradiated sample. The potentialities of this new oxygen isotope analysis method, based on the use of an electron accelerator, are described. Detection limit of 0.1 μg18O is easily attainable. The equipment designed and built to industrialise this technique is described. It allows a hundred samples to be analysed automatically, the accelerator, detection instruments and pneumatic transfer circuits being controlled by a logic system linked to an electronic chronometer.