International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators
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AP/IE-02
Neutron Transmission: A Very Powerful Technique at Small Accelerator-Based Neutron Sources R. Santisteban2,3, J.R. Granada1,2,3, S.N. Petriw2, and R.E. Mayer1,3 1Comisíon Nacional de Energía Atómica, Bariloche, Argentina Corresponding Author: granada@cnea.gov.ar The determination of total cross section of a material as a function of neutron energy by means of transmission experiments is rather easy on a pulsed neutron source. The spectrometer and associated instrumentation required may be described as relatively simple, and sound statistical data are achieved even using a small, accelerator-based neutron source. Despite its simplicity, detailed scientific and technological information can be extracted from such measurements, at the cost of fairly elaborate data analysis techniques. These features make this an attractive tool for neutron-based materials research within small research groups. Different physical properties of a material manifest over the different neutron energy ranges. At our group we have focused on the determination and analysis of the total cross section for thermal and sub-thermal neutrons, which is very sensitive to the geometric arrangement and movement of the atoms, over distances ranging from the “first-neighbour scale” up to the microstructural level or “grain scale”. We will describe our experimental facilities, based on a 25 MeV electron LINAC, together with our current research topics, focused mainly around structural nuclear materials and moderators. Besides this, we will present current efforts aimed at expanding the variety of problems feasible to be studied by neutron transmission experiments. These efforts comprise experimental work for reducing experimental counting times, and maybe more importantly, theoretical and programming work aimed at producing a powerful data-analysis program for efficient materials characterization. We will show examples illustrating the use of neutron transmission for the study of crystalline materials. In particular we will present non-destructive studies dealing with the identification and quantification of phases, lattice parameters and preferred orientation in zircaloys, metal hydrides, steels, and copper-based alloys.
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