Recent developments on micrometric fission chambers for high neutron fluxes

ISBN 9781424452071International audiencewith the development of innovative nuclear systems and new generation neutron sources, the nuclear instrumentation should be adapted. Since several years, we developed microscopic fission chambers to study the transmutation of minor actinides in high thermal-neutron fluxes. The recent developments done to fulfill the drastic conditions of irradiations are described in this paper together with the feedback from the measurements. Two installations were used: the HFR of the ILL for its highest thermal neutron flux of the world and the MEGAPIE target which was the first 1 MW liquid Pb-Bi spallation target in the world

Indirect and direct measurement of thermal neutron acceleration by inelastic scattering on the 177Lu isomer

When neutrons interact with isomers these last can be de-excited. In such a reaction the outgoing neutron has an energy greater than the ingoing one. This process is referred as Inelastic Neutron Acceleration or Super-elastic Scattering. Up to now this process was observed for only two nucleus, 152mEu and 180mHf by measuring the number of fast neutron produced by isomeric targets irradiated with thermal neutrons. In these works the energies of the accelerated neutrons were not measured. This report presents an indirect measurement of inelastic neutron acceleration on 177mLu, based on the burn-up and the radiative capture cross sections measurements. Since at thermal energies the inelastic scattering and the radiative capture are the only processes that contribute to the isomer burn-up, the inelastic cross section can be deduced from the difference between the two measured quantities. Applying this method for the 177Lu isomer with different neutron fluxes we obtained a value of 258 (58) barns, and determined that there is no integral resonance for this process. In addition the radiative capture cross section on 177gLu was measured with a much better accuracy than the accepted value. Since the acceleration cross section is quite high a direct measurement of this process was undertaken, sending thermal neutrons and measuring the fast neutrons. The main goal now is to measure the outgoing neutron energies in order to identify the neutron transitions in the exit channel. In particular the K conservation question can be addressed by such a measurement

The Antarctic Submillimetre Telescope

This report aims to provide a summary of the status of our Antarctic Submillimetre Telescope (AST) project up to date. It is a very new project for Antarctic astronomy. Necessary prerequisites for a future deployment of a large size telescope infrastructure have been tested in years 2007 and 2008. The knowledge of the transmission, frost formation and temperature gradient were fundamental parameters before starting a feasibility study. The telescope specifications and requirements are currently discussed with the industrial partnership

The Antarctic Submillimetre Telescope

This report aims to provide a summary of the status of our Antarctic Submillimetre Telescope (AST) project up to date. It is a very new project for Antarctic astronomy. Necessary prerequisites for a future deployment of a large size telescope infrastructure have been tested in years 2007 and 2008. The knowledge of the transmission, frost formation and temperature gradient were fundamental parameters before starting a feasibility study. The telescope specifications and requirements are currently discussed with the industrial partnership